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Sunday, December 3, 2017

Pasture Irrigation

We are having a debate in New Zealand for and against irrigation.  It really boils down to a debate on our dairy herd.  With irrigation, you can put cows on land that otherwise would not support them and our dairy herd increases and with it the pollution of our environment. True, there are some concerns about irrigation itself.  For instance, the need to dam a stream in some cases to provide the water or the misuse of irrigation water.  Actually, using more water than is needed is a thing of the past for any farmer worth his air conditioned tractor.  Sensors tell the farmer just how much water he should apply.  The primary concern is the expansion of our dairy herd which is possible with irrigation and the potential for  environmental pollution.

To come out for or against irrigation  may be good for radio sound bites but as with most cases in the affairs of man, the devil is in the details.Clearly we need irrigation for our farmers to fill in the gaps left by nature. Even in the best areas, there are periods without rain.  A farmer needs reliable inputs to be able to run his business.

Equally clearly, if we can not find ways of farming that preserve our environment then the crude sledge hammer method of reducing herds and restricting where they can graze must be taken.  The question is, can we have dairy herds and not pollute.  The answer may be yes for some areas and no for others and will depend, to quite a large extent, on the details of how we farm.

The core of the problem is to be able to apply the waste output of the cows back on to the land in a way, in a concentration and at the right time such that it constitutes a valuable fertilizer and not an environmental pollutant. If this can be done, darying is no longer a source of pollution.

Throughout history, societies that trashed their soils, declined and disappeared.  One factor in trashing soils is not returning nutrients to the soil that are extracted.  In so far  as is possible, nutrients must be returned in an organic form that benefits the soil organisms.  Quite clearly, the urine, manure and spilt milk from a dairy herd constitutes a valuable resource for the enhancement of the soil.

That is not to say that chemical fertilizer should not be used but as you will see, much less of them can be used if farming methods are tweaked.

If farming remains a process of plow, add chemical nutrients, sow the seeds and irrigate then our soils will degrade, pollution will be rampant and we will go the way of many previous societies that mined their soils  instead of farming them.

It takes a lot more 'smarts' to farm in a way that improves the soil, reduces  inputs, increased water infiltration, improves the bottom line and leaves you with a much better farm to pass on to your children or to sell than when you started.

Let's look at some of the tools we have available.

Riparian Zones
Fencing off streams and encouraging the growth of trees, shrubs and grasses between the fence and the stream is a great help.  Not only does it stop the cows from entering the stream and urinating and defecating into it but the roots of the vegetation of the riparian zone take nutrients from the water table which is slowly flowing toward the stream.  However, it has been reported that 70% of the nutrients entering the streams comes from the very small feeder streams and ditches.  It is simply not possible to fence off every little feeder stream.

Composting Barns
Composting barns use deep layers of wood shavings or coarse saw dust as bedding and the cows are bedded down at night and have free access to the barn to escape inclement weather.  The bedding is stirred mechanically every day, keeping it aerobic.  It has been found that cows prefer such an environment to bed down even choosing it ahead of a straw-lined byre.  The composting process produces heat which reduces the feed need of the cows and a rich compost eats up pathogens.  The compost captures all the nutrients from the waste of the cows including N and S which in an anaerobic system go off as the gases NH3 and H2S.

The bedding can be applied to the fields at the correct concentration and correct time which most benefits the soil and the pasture and hence causes no pollution.  Some research needs to be done on what portion of the effluent of a cow is released while in such a barn compared to what proportion is released out on the pasture*.  Do they mainly urinate and defecate at night or in the day, while they are grazing or when they are chewing their cud.  this would give an indication of how much of the nutrient stream could be captured by a composting barn.

*Great job for some long suffering masters student

Bio-Gas Generators.
Finally, a farm in Southern New Zealand is using the waste produced in the milking shed* to generate bio-gas.  The biogas is use  to produce electricity. The waste heat from the motor which drives the generator is used to heat the water used in the milking shed.  This combination makes for a very efficient system, energy wise.  The effluent from the biogas generator contains almost all the nutrients in the waste stream since only C and H have been taken off as biogas (and some of the S).   As with compost bedding it can be applied to the fields when and in what concentrations most benefits the pasture and hence least pollutes the environment.

*More work for that long suffering student.

Managing the Pasture
We have now removed a portion of the waste stream with Riparian zones, compositing barns and biogas generators.  Let's see what we can do out on the pasture.  There is a fantastic book by David R Montgomery called Growing A Revolution; Bringing back our soils.  In it he describes visiting farmers all over the world who have independently come up with a way of farming.  The methods they use would be familiar to any farmer before the advent of cheap chemical fertilizers but each method is updated in light of modern knowledge. Farming this way results in an improved bottom line, slashed pollution to the environment, reduced farming costs, increased infiltration of rain, continually improving soils  and the sequestering of significant amounts of carbon in the soils.  It also, due to the greatly increased organic content of the soil, results in the capture of much of the Nitrogen when a cow urinates. The urine is soaked up by the organic material giving the soil organisms time to scavenge the nitrogen.

Before we go off half cocked and reduce one of our most valuable industries, we must pay attention to the details.  Farming can not be allowed to degrade our environment but there are farming methods which address this problem.  The devil is in the detail.

Tuesday, November 28, 2017

The ice pump

It has been a bit of a mystery why the floating ice around Antarctica has been increasing in area over the last few decades despite global warming.  After quite a bit of research and some reference to some well known physics, there is a pretty plausible theory/story to explain this.  It is called the ice pump.  First we need a fact or two before we tie it all together.

1.  Sea level is rising but only some of this rise is  due to the melting of land ice.  The remainder is due to the expansion of the water of the oceans as it heats up.  The heat is being gradually stirred into deeper and deeper water.  The salty deep 'circumpolar water' around the Antarctic is  a case in point.

2.  H2O expands when it freezes, contracts when it melts.  It makes intuitive sense that as you apply pressure to ice, it will melt at a temperature below zero degrees centigrade.  Indeed this is observed experimentally.  If you have ever skated you have used this phenomenon.  the blades of an ice skate are very narrow and apply high pressure to the ice which melts under the blade and allows the skates to slide over the ice.

 Image result for table melting point of ice under pressure
 100MPa equals about 9950m so one interval across the horizontal axis is about 2480m.  At this depth the melting point of ice is depressed about 2.4 degrees C.  As you can see from the following illustration, the depth of the bottom below sea level in West Antarctica is well below 2000m



3.  A few glaciers on East Antarctica and most on West Antarctica are on a retrograde slope.  The ice is so heavy that it has depressed the land and the land bottom below the ice gets deeper and deeper as you go inland. In East Antarctica some outflowing glaciers have carved deep channels well below sea level.   Most of West Antarctica land is way below sea level.

So let's put all this together.

The deep circumpolar water over-tops the sill at the outlet of some of the glaciers.  It is salty which keeps it below the surface, fresher water despite the fact that it is a little warmer.

Being heavier, it flows down the sloping sea bottom under the floating ice until it comes to the grounding line.  There it comes into contacts with ice.  Not only is it salty and warm but ice melts at below zero under pressure so this salty bottom water melts the ice at the grounding line making the grounding line retreat landward.

The glacier is moving seaward under the pressure of ice from the interior but grounding lines have been observed to be retreating so clearly the melting is  faster than the flow of ice seaward.

As the grounding line retreats it is at greater and greater depth and hence at a higher pressure where ice melts at lower and lower temperatures.  The melting becomes greater for a given quantity and temperature of circumpolar deep water flowing down the slope.

When you mix the water from the melting ice with this  salty deep polar water, the mix is fresher and hence lighter than the deep water.  It flows up the slope of the ice ceiling in a sort of up side down river and flows out on to the surface of the ocean.  The deep water is often described as seeping under the ice or some such gentle term.  We can see that as the light super cooled water flows out on to the surface of the ocean, deep water is being sucked in under the ice.   The more water flowing out on the surface the greater the 'suck'.

As the lighter water flows upward into a zone of reduced pressure, it is below the freezing point of ice at that depth.  It begins to freeze and for some reason freezes in thin sheets called platelets which form a sort of mushy layer below the sea ice ceiling.    This is the ice pump.  It is in effect taking ice from the grounding line and depositing it in shallower water under the ice ceiling.  The deeper the grounding line, the more effective the pump.

The sea ice around the Antarctic continent disappears every year or two so this ice from the grounding line is lost to the continent.  ie contributes to sea level rise.

The water which flows out on to the surface of the ocean, either at the edge of the ice shelf or into a lead is still super cooled and freezes readily, especially as it comes into contact with Arctic air which is well below freezing.  Here is one small part of  the explanation of the increasing ice around Antarctica.  Any leads which open up due to wind and currents, fill rapidly with ice  and hence can not close up again if the wind changes.

As the ice is eroded from underneath the glacier, the floating part of the glacier deflates and increases the slope of ice from the interior, seaward.  The glacier speeds up, pushing more ice seaward.  This is another part of the expansion of the floating ice.

The increased flow of ice seaward should push the grounding line seaward but apparently, at present,  melting trumps glacier flow.  In addition as the glacier deflates it floats up off the ground.  This also contributes to moving the grounding line landward.

There are a couple of further wrinkles to this story.

The rising water flowing up the ice ceiling apparently, in at least some locations, carves out up side down valleys in the ice and the light water collects in these and flows seaward.  This will, of course, reduce the surface area where this light up-flowing water is in contact with the surrounding water.  It is not quite a pipe but will reduce mixing compared to a sheet flow.

In addition, these valleys have reduced buoyancy compared to the surrounding ice so will weaken the ice shelf, contributing to it's break up.  If, for instance, you had one valley running along the middle of an ice shelf, the surrounding ice would have a force on it trying to make the ice tip toward the valley from both sides.

Another factor in the expansion of the surface area of floating ice is that the air flowing off the Antarctic continent is apparently getting stronger and this will tend to push ice outward (North).  As mentioned, leads opened up will rapidly freeze, stopping the ice from moving back south.

The winds flowing clockwise (looking down on the continent) around Antarctica are apparently also increasing in velocity.  They push on the ice.  Anything moving in the southern hemisphere and especially if it is near the pole, is veered to the left by Coriolis.  To the left is away from the continent.  Again we have ice moving North and leads freezing over, stopping the ice from returning south.


The bottom line of all this is that for a while, we would expect the floating ice to increase in area around the Antarctic due, ultimately, to the warming of the deep salty circumpolar water.  At the same time, we should expect to see coastal glacier deflating and the floating ice shelves breaking up.  Already two of the Larson Ice shelves along the Arctic peninsula have disintegrated.  They are the Northern most Antarctic ice shelves.  The third Larson Ice Shelf may be on its way and the rest should follow in time.  This will remove the plug and allow inland glaciers to flow more quickly and we will see if this movement can reverse the retreat of the grounding line.  This is unlikely as the glacier deflate and float upward.

What is interesting is that we have probably passed a tipping point in the break down of glaciers which are grounded way below sea level.  When the salty deep circumpolar water contacts ice at relatively shallow depths, it will erode the ice but the flow of ice seaward may be able to balance the melting.  However, when this circumpolar water is contacting ice at greater depth, its erosion ability is greatly increased due to the suppression of the melting temperature of the ice at greater depth and hence pressure.  The removed ice is transfered to the underside of the ice shelf at shallower depth and this ice is lost each summer as it floats off into the ocean.  Even if the deep circumpolar water cooled to its previous temperature, the depth effect has so increased the ability of this water to melt ice that the process would likely continue.  Since there is no prospect that such a cooling will occur, it is doubly likely that the ice sheets which are grounded well below sea level will collapse.

The disintegration of the Antarctic ice which is grounded below sea level is now probably inevitable, even if we were to stop all green house gases tomorrow.

I wouldn't be buying any coastal property

Friday, November 10, 2017

Dirt

This is a book review of David R Montgomery's book Dirt which he wrote before Growing a Revolution.  In Growing a Revolution he describes how a few farmers scattered far and wide across the planet have worked out a better way of farming which restores the soil with all the benefits this brings.  In this book Dirt, he describes how civilization after civilization,with very rare exceptions, have destroyed themselves by trashing their soils.

Clearly there are other factors involved in the demise of civilizations but at the core, if you can't feed your population, you are on a slipery slide.

A common sequence Prof Montgomery describes is a move into a new valley and a build-up of farming.  With a reliable source of food, human populations  increase at a truly astounding rate.  In the words of one of my favorite authors, Richard Dawkins,  "If ever there is an increase in food production, population will rise until the previous state of misery is re-established." It is not inevitable but very very common. 

In a few countries the population increase and with it the destruction of ever more sensitive soils has been reversed and would you believe it, we are fighting it tooth and nail. (see above link).


As the bottom land is completely occupied, the new generation of farmers move up slope and farm ever steeper land.  When the plow is used, the die is cast.  Plowing moves soil down hill and the removal of ground cover greatly accelerates natural erosion by rain and wind which, moves the soil even faster down hill.  Soils either accumulate on the valley bottoms and/or are washed into the stream or river to be exported to the sea.

  For instance, early in American (European) farming, they plowed straight up and down the slopes, would you believe???  Contour plowing was a "great innovation" and even this "innovation" only slowed down the destruction.

 The Americans eventually reached the great central Loes plains, leaving destruction behind them and proceeded to destroy these soils as well.

On a visit to Virginia I saw many stone gates leading into a young forest with no drive way visible.  When I asked the locals about this curious occurrence, they told me that these were abandoned tobacco and cotton farms.  The farmers had moved west when the soil ran out.  In fact, it was common for a farm to last only for a decade or two when the farmer had to move west.  This, more than anything might explain the constant western movement of the Americans into lands owned by the first people.

On a recent visit to Otterton, in Devon to see the return of the beavers we were told that Otterton was once a sea port.  Soil erosion had filled the estuary and Otterton is now land locked.  We found out later that this is a very common situation around the UK.

Just last month, we took a trip to Bulls in North Island (New Zealand)  There we saw plowed fields all over the place and the streams ran brown with silt.  Our streams here in Canterbury are the same when there is anything above a very gentle rain.

the present zeitgeist is climate change and we are finally waking up to its dangers.  The more serious crisis may just possibly be the destruction of our soils. This is exacerbated by our short term rush to the maximum short term profit rather than a greater long term profit.

Friday, October 13, 2017

Carbon dating and the Math

One would have to be a hermit not to have heard about carbon dating.  This is the dating, for instance, of a piece of wood in an old building or a piece of charcoal in an archaeological dig.

At a first approximation, the physics is pretty straight forward.  An atom consists of a nucleus with electrons whizzing around the nucleus.  Which element the atom is depends on the number of electrons and the number of electrons, in turn, depends on the number of protons in the nucleus.  In a normal, unionized atom, the number of electrons and protons are equal and the atom is neutrally charged.

The glue that holds these positively charged protons together in the nucleus (remember like charges repel each other) are the neutrons.  Don't ask me how they do this.  The explanation is way above my pay grade.  Very roughly speaking, there are the same number of neutrons as protons but this can vary.  Carbon, for instance, can exist in a state with 6protons and 6 neutrons for an atomic mass number of 12. It can also exist in a form with 6 protons and 8 neutrons for a mass number of 14.

These two types are called isotopes of Carbon.  There is a third one but it is not needed for this explanation.

Some isotopes are stable, some are not (why is also above my pay grade).  In the case of Carbon, 12 is stable, 14 is not. 

Carbon 14 disintegrates into Nitrogen 14 with the ejection of an electron from one of it's neutrons.  The neutron becomes a proton so the atom is now a new element with 7 protons and 7 neutrons, hence 14N.

No one knows when any individual Carbon 14 atom is going to disintegrate.  There is a very small probability at any one moment but when you have a lot of 14C, you can predict how many atoms will change to 14N in any given time period.  This results in something interesting which has been observed experimentally.  If you know how much of the radioactive element you have, you will observe that half of it will break down in a given time, referred to as it's half life.  The half life of various radioactive isotopes varies from tiny fractions of a second to many millions of years.

In the case of 14C, it's half life is 5730 years give or take 40 years.

In 5730 years you will have half left, in another 5730 years, a quarter of the original amount, in one more half life, one eighth of the original amount and so forth.


So now we need the math for this.  We will work out what I call the straight forward formula and then we can change it around (solve for other parts) so that each component of the formula becomes the subject.

First a note on mathematical notation.

What is meant when you see a symbol.

xA means multiply the A by x.  If A is 2 and x is 3 then xA is 6

Ax means multiply A by itself x times.  If A is 2 and x is 3 then Ax is 8.  In words, A is raised to the xth power.

However, in the symbols Ax,  x is not an operator.  ie, it doesn't say to do anything.  It is a label.  It means the xth A.  For instance you could have A1, A2, A3 etc.  This is the first, second and third A.  Or Ao and At which for our purposes will mean A at time zero and A at a specified future time.

There is a special one in Chemistry.  I'll use Carbon since this is what we are talking about.  For instance 14C.  This means the carbon atom with 14 nucleotides.   ie, The sum of neutrons and protons adds up to `14.  There also exist 12C and 13C.  Of course both have 6 protons or it wouldn't be Carbon.  The number of neutrons varies.

And one more in Math.  If the subscript is after the word log such as log5 then it means log to the base 5.  If only log is used, it is understood it is to the base 10.   That is to say, log = log10 and if ln is used it is to the base 'e'.  Don't worry about it, we don't need 'e'.  I only mention it because it is on your little hand held computer and you might wonder.

Lets go back to the basics.  Every half life period, (h) the amount is halved. In the case of Carbon, the half life is 5730 years but half lives for other isotopes varies hugely.   Lets call the amount we start with as Ao (A at time zero) and the amount we are left with as At (A at some time t in the future).  The amount we will have left after one half life is:

1.   A1 = Ao(1/2)1

After two half lives
2.    A2 = Ao(1/2)2

After three half lives
3.    A3 = Ao(1/2)3
Remember 1/2 times 1/2 is 1/4.   Multiply once more by 1/2 and you have 1/8.  When you see a times sign between fractions, replace it in your mind with "of".  then 1/2 x 1/2 becomes one half of one half.

The 1,2 and 3 are the number of half lives that have gone by.

4.  So An - Ao(1/2)n  or in words, to find the amount of a substance after n half lives have gone by, multiply Ao, the initial amount, times 1/2 raised to the nth power.



Note that in the notation Ax,  x means the amount at time x expressed in half lives.

Also note that even if the n is not a whole number and therefore would take a wee bit of higher math (knowing logarithms), to solve, your computer does this with no problem.  Your high school computer can solve, for instance, 63.22 without raising a sweat.

Suppose we start with one gram of a radioactive substance and one half life has gone by.  We simply multiply 1gram times 1/2

Suppose 4 half lives have gone back.  We multiply the one gram times (1/2)4.  that is to say by 1/2 times 1/2 times 1/2 times 1/2 which equals 1/16th times the original amount.

Now suppose we know what the half life (h) of a particular isotope is.  Say it is 10 years, for simplicity.  Say 30 years have gone by.  Obviously 3 half lives have past.  In other words n, the number of half lives equals the time elapsed (t) divided by the Half life (h).  In this case n = 30/10 = 3.

5.   n=t/h.

And, as I said, it doesn't have to be a whole number.  If the half life is 10 years and 75 years have gone by then n = 75/10 = 7.5.  With simple math we would have a problem raising a number to a fractional exponent but your computer has no such problem so don't sweat it.

You can see where this is leading.  Since n=t/h, we can substitute t/h into the formula where we see n.

The radioactive decay formula then becomes

6.  At = Ao(1/2)t/h
or in words, to find the amount of radioactive material remaining after time t, multiply Ao, the initial amount, times one half raised to the power of t/h.


Good heavens!  I forgot to tell you where the radioactive Carbon comes from.  If it's half life is only 5730 years, in about 50,000 years there will be so little of it that carbon dating is out of the question and the world has been here for over 4b years.  Clearly, 14C must be being created somewhere.  the 'Where',, is in the upper atmosphere.  As cosmic rays hit the upper atmosphere, they are so energetic that they cause some nuclear reactions and one of these is to change some14N into 14C.  It is a very small amount but enough to be detected in living material with modern methods so we have a clock we can use.  When an organism dies it stops taking up carbon and the clock starts to tick.  If we  analyze it sometime in the future, we can know when it died (up to about 50,000 years).

Now we can do what a mathematician calls solving for Ao or for t or for h.  In other words we re-arrange the formula so that each of these terms in turn become the subject of the formula (ie. is by itself on the left and everything else is  on the right). I'll tell you what each variation of the formula is good for as we rearrange them.

The basic principle of solving for a factor (one of the letters) in a formula is that we can do anything we want to one side as long as we do the same to the other side.  After all if I have a formula that 7 = 3+4, if I multiply both sides by, say, 5, the formula is still correct.  Of course we don't just do random things to both sides of the formula. The trick is to do something that gets us closer to the solution we are looking for.

One other thing.  At one point in the procedure I am going to have to take a log of both sides.  Even if you don't understand logarithms, this should pose no emotional problem since I am doing the same to both sides.  Then, however, you are going to have to take my word for a 'log identity'.  If you are into logarithms, you will understand why the identity holds but if not, don't sweat it.  It is true.  This identity is:

logabc = clogab.  Incidentally, the inverse of the left side of this formula is ac =b.  That may give you a clue why the identity works.

In words:   log to the base 'a' of 'b' raised to the 'c'th power equals c times the log to the base a of b.

So let's start.  I want to end up with a formula for each of the terms, in turn, on the left side of the equation.

The original equation is

At = Ao(1/2)t/h

Let's divide each side by (1/2)t/h.  Note that this cancels out the (1/2)t/h on the right side and leaves it on the left in the denominator*.  It is more conventional to have the subject of the formula on the left so we will exchange them.  After all if 7 = 3+4 then 3+4 = 7.  Our formula then becomes

* The bottom part of a fraction.

Ao = At divided by (1/2)t/h. Don't know how to get my computer to write this so I will leave you to write it down on a piece of paper.

Use
So what is this formula good for.  It was noted early on in the use of carbon dating that there were some discrepancies.  With artifacts for which the exact date was known, the Carbon date did not agree.  The hypothesis was that the rate of 14C production in the upper atmosphere might not have been constant over the years.  So cores were drilled into very old trees, the rings were separated and carbon dated.  The above formula was used to work out the concentration  of carbon 14 which had been present for each year  that a ring was laid down.  And indeed it was found that the true curve diverged by a small but significant amount over time from the theoretical curve.  When the true curve was used, the dates all fell into place.
 

Now let's work on t and h.  The first thing I will do is to divide both sides by Ao.  This cancels Ao on the right side and leaves us with

At/Ao = (1/2)t/h

Now I'll take the log of both sides

log (At/Ao) = log[(1/2)t/h]

Remember our identity.  I can take t/h to the front of the right side so

log(At/Ao) = t/h(log1/2)

Now it is simple.  I simply divide both sides by log1/2 and we have t/h by themselves on the right side.  You take it from here.  Isolate t and h.  If you do it right you will find that

t = [hlog(At/Ao]/[log(1/2)]

and

h = [tlog1/2}/[log(At/Ao}

Use
How about the formula for t.  This is pretty obvious.  Now that we have the needed correction of the production of 14C over the past , we can date any object that was once alive up to about 50,000 years.  This is carbon dating.

Use
How about h.  We can't actually wait around for 5730 years to see when we have half of a quantity of radioactive carbon left.  We can, thought, observe the rate of disintegration on a shorter time span.  Using the h formula we can work out the half life of each radioactive isotope and some of them are multi millions of years.

It is never that easy

There are always complications.  Charcoal, for instance, if it is in ordinary soils or even in a cave can be colonized by micro-organisms.  If in active soil, the micro-organisms will have a modern carbon signature.  One has to first clean the charcoal of the modern material in order to get the correct date for the charcoal

Add to that, that we have been spewing carbon into the atmosphere from fossil fuel.  This is old carbon and hence contains no Carbon 14.  On the other side we have had nuclear tests in the air.  They have added Carbon 14 to the air.  For future anthropologists, they will have to take this into account.

Other types of radioactive dating have their own special requirements.  For instance when a rock melt cools, crystals form and just as a solution of salt and sugar, as it crystallizes, will  produce crystals of pure salt and pure sugar, the  crystals in a melt are of one type of molecule.  If one of these is a radioactive species and it's end product is known you can measure the concentraton of both and calculate when the rock  was melted. 

Tuesday, October 3, 2017

The Anthropocene

This is a book review of William F Ruddiman's book, Plows, Plagues and Petroleum.  It's premise is that the Anthropocene* didn't start some 200 years ago with the beginning of the industrial revolution and hence the burning of fossil fuels but actually started 6000 to 8000 years ago.

* The age in which humans have started to have a significant effect on the climate

In the popular literature you will often find comments such as 'we live in a very unusual period.  Our climate, compared with previous times, has been remarkably stable for thousands of years'    That is not to say completely stable.  We have had the so called little ice age for instance and the medieval warm period but compared to the climate as read in ice cores, this has been a period of great stability.

Prof. Ruddiman basis much of this contention on information from ice cores.  In Antarctica, cores have been drilled which reach ice which was deposited around 800,000 years ago.  Over this period the alteration between glacial periods and interglacial periods* has had a cycle of about 100,000 years.  Here is a most amazing graphic of the past cycles.

* Note that I say glacial and interglacial period, not ice age.  Strictly speaking, despite popular usage, an ice age is the approximately 3m year period we are in with approximately 50 or so glacials and interglacials.  If we want to use the term ice age, for instance, for the time between the previous interglacial (the Eemian) and the present interglacial (the Holocene) then we need another name for the approx. 3m year period of alternating cold and warm periods that we are in the middle of right now.

What has caused these warm and cold periods has been pretty well established as the Milankovitch cycles.  There are three of these which have different periodicities.  There is the tilt of the earth  which varies between 21.2 and 24.5 degrees from the plane of it's orbit.  it is called Obliquity for some reason.  It's period is about  41,000  years.  There is the eccentricity of the orbit which varies from round to elliptical and back with a period of 100,000 years* and there is the orientation of this ellipticity in space which will result in the earth being closest to the sun in summer or closest in winter.  This has a period of 23,000 years and is called axial precession

It is a little more complicated than this.  For instance Eccentricity has a number of components.  It is not a simple sin wave but that will do for now.

Adding these three cycles together you get a variability in the strength of the sun on the surface of the earth and most important, in the mid to high latitude area of the Northern Hemisphere (where most of the land is).  To go into a glacial (glacial period), the insolation (Amount of radiation reaching the earth's surface) must be low in the Northern Hemisphere summer.  This allows snow to remain over the summer and to be increased during the next winter. Then the more land that is covered continually with snow, the more solar radiation is reflected back into space and we have a feedback which accelerates the process.  I won't go into how glacials end but you can go here and here for some ideas on how this occurs.

Over many many glacial-interglacial periods it has been observed that Carbon dioxide rises as the ice melts (some controversy on why) and a little before maximum melt, Carbon dioxide begins to fall.  Following this, with the odd up-tick CO2 falls continually.  At a certain level of Carbon dioxide, combined with the right part of the Milankovitch cycle, snow begins to accumulate, bringing on the start of the next glacial.

Since the Milankovitch cycle is the sum of three cycles, each with a different period, each glacial-interglacial cycle is somewhat different.  Looking at these cycles, the two which are most like the present one that we are in are the 4th and the 9th back from our present one.

In both these cycles (and in other less similar cycles) Carbon dioxide began to fall and just continued to do so, starting a little before maximum melt and falling to about 185ppm.

Our recent (Holocene) interglacial started some 20,000 years ago by definition since that was when the ice sheet was at it's greatest extent but melting really got under way about 11,500 years ago.  And as with all other cycles, Carbon dioxide began to rise.

Then, as usual, just before maximum melt, Carbon dioxide began to fall.

If it had continued, then at a certain point, snow would have begun to accumulate again.  Apparently the 'epicenter' of ice accumulation is on the high lands of Baffin Island and somewhat later in Labrador.  It didn't happen.  Around 6000 to 8000 years ago, the concentration of Carbon dioxide began to climb in complete contrast to other cycles.  It wasn't enough to fully counteract the downswing in the  Milankovitch cycle  but greatly slowed down the cooling.

It had almost reached the level for snow accumulation when there were two catastrophic events in human History.  One was the Black Death which scythed down huge numbers of people* in Asia, the Middle East and Europe.

It is often noted that this was the beginning of the rise of the rights of the serfs since they were in such short supply that they could demand better conditions in exchange for their labor.

The second was the invasion of South America by the Spanish.  The Spanish brought with them a plethora of deadly diseases for which the local population had no resistance.  Disease spread through south, central and North America and decreased the population*, by some estimates, by 90%.  In both plagues forests grew up on deserted farm lands and drew down Carbon dioxide below the level needed for the beginning of snow accumulation.

*Contrary to popular opinion, archeology has now confirmed that North America was populated by a large number of people, many of them living in what we would characterize as  advanced civilizations.

There is some very interesting evidence that glaciation  started.  Around the high lands of Baffin island there is a 'halo' of dead lichen with young new lichen beginning to grow here and there.  What happened?

Apparently, snow began to accumulate and last through the summer and occupy more and more area and of course smothered the lichen.  Then  along came the industrial revolution and the snow retreated again leaving this halo of dead lichen.  We were that close to beginning, once more, to slide into a glacial.

So what did man do to slow the advent of a new glacial for long enough for the Industrial Revolution to take over and really up the concentration of this green house gas.

First there was the burning down of forests to simply roast and catch animals. Areas burnt off, and especially if burnt off regularly, became grass lands which attract grazing animals and in which it is much easier to hunt.   In Australia, this probably started around 50,000 years ago when man first reached that continent.  Then as agriculture started, forests were cleared to plant crops.  An early technique was to simply ring bark a tree and then plant a fire at the base once it had died and dried out.  As the bronze age and then the iron age took hold, we could simply fell the trees.

Very soon after that, the plow was invented.  We have seen the tremendous damage the plow can do in modern times with the destruction of the soils of the great plains in America.  These were reservoirs of huge amounts of carbon which the plow released into the atmosphere.  If you travel through the Middle East you see clearly all the exposed rock.  The soils there have not only released their carbon but have been washed into the sea.  Farming with the plow is mainly responsible.

In the Far East the cultivation of rice in ponds was developed.  Anaerobic ponds give out large amounts of Methane which is a very powerful green house gas.  It oxidizes to the less potent Carbon dioxide and so stays around in a less toxic form.  This development reversed the methane trend.  Of course to build the extensive rice ponds, often terraced up the sides of mountains, you first have to eliminate the forests.

Sunday, October 1, 2017

Composting barns

I've just read an article on composting barns  in our local farming magazine.  We are re-inventing the wheel but that is OK.  I saw this system in 1989 in South Africa and they had been using it for some time.  So what are they.  First a little background science.

You can classify the break down of organic material into simpler substances which are available for the growth of plants, into two main types.  This break down can occur aerobically or anaerobically.  The results are different.  With anaerobic break down, the processes are less energetic and two significant by-products are ammonia, NH4, and Hydrogen sulphide, H2S, (which in the air oxidizes to Sulphur dioxide and water.  SO2  H20). Both Ammonia and Hydrogen sulfide are gases and go off into the air.  In doing so, they  take with them the valuable nutrients Nitrogen (N2) and Sulfur (S). 

Aerobic processes are far more vigorous since the strong oxidizer Oxygen (O2) is present and only produce Carbon dioxide (CO2) and water.  In aerobic break down a whole ecology of microfauna build the available nutrients into their body mass. Aerobic processes can use cellulose and lignin as a source of Carbon and energy*.  In anaerobic processes, both are refractory. As long as the source of organic carbon lasts, the waste products of each trophic level are built back into body mass by the primary producers*.  Finally in this system, as organic carbon runs out, nutrients are released in a form that plants can use.  The ecology runs down and the final product left is Humus which has some interesting benefits for the soil.


*  In a photosynthesis system, the primary producers are plants.  In the sea, they are primarily single cell algae and sea weed.  In a compost pile they are micro-organisms and if the source of carbon and energy is wood (cellulose) then the micro-organisms which produce cellulase, the enzyme that can cut off the sugar mollecules from the cellulose are the primary producers.


In a composting barn, you provide a source of carbon in the form of saw dust or wood shavings. You could also use pelleted paper or any other source of cellulose.  Cellulose is an interesting substance.  It is a poly-sacaride.  In other words a chain of sugar molecules joined together in an insoluble form.  No multi-celled animal can digest this material.  Some bacteria, on the contrary, produce cellulase*.  While algae are the primary producers in the sea, cellulase producing micro-organisms are the base of the food chain  in a cellulose rich compost.

Enzymes are named for the substance that they can catalyze the use of.  Hence the enzyme that helps metabolize sucrose would be called sucrase while the enzyme that metabolizes cellulose is cellulase.

Of course the cellulose is not enough for these micro-organisms.  They need the other nutrients such as nitrogen, phosphorous, sulfur and so forth to build their bodies.  They scavenge these from the environment and they themselves become food for a whole range of grazers who build these substances into their bodies.

As a rough rule of thumb, each level in the trophic chain can incorporate about a tenth of the material from the level below it.  A ton of phytoplankton can make a tenth of a ton of Krill which can make a hundredth of a ton of whale.  The remaining 90% at each transfer goes back into the soup to be used again by the primary producers.

As long as there is a source of energy, such as sunshine in the case of phytoplankton or cellulose in the case of a compost pile, all these nutrients are re-incorporated into biomass.  When the energy source runs out, there is a net release of nutrients as the various micro-organisms feed on each other but with no energy and Carbon source to power  the uptake of the released nutrients*

* This is why it is so bad to mix saw dust into your soil.  All the free nutrients will be scavenged until the saw dust is used up.  Then nutrients will be released and the plants can start to grow again.

So how about composting barns.  In these barns there are a number of requirements.  First, you need a thick layer of cellulose as bedding.  The urine and dung of the animals living in the barn (or visiting it) is absorbed by the saw dust or wood shavings.  The farm we visited in South Africa used the coarse saw dust from a saw mill.  But that is not sufficient.  The bedding must be kept aerobic.  In Africa, where I first saw this method, they were growing chickens.  This is possibly easier than growing cows because the urine of birds is almost solid.  Cows, by contrast, produce copious amounts of urine.  Labor in South Africa at the time was not expensive and the saw dust bedding of the chickens was stirred each day by hand.

In the case of a cow shed, one would have to have a mechanical method of stirring the bedding.  Cows go for milking and in some systems, go to graze during the day. giving a perfect time to aerate the bedding.

Note that the metabolism of all these wee beasties in the compost give off heat just as you and I do when we metabolize.  The bedding is warm and it has been reported that given a choice, cows will bed down in these barns in preference to staying outside or going into stalls with straw on the floor.

As you can imagine, ventilation is of the greatest importance as well.  No poisonous gases such as Ammonia or Hydrogen sulphide are given off but Carbon dioxide is produced.  A sloping roof with vents at the top of the slope and good access for air from the sides is vital.  The heat from the bedding and the not inconsiderable heat from the cows will create a natural convective circulation.  It is also useful to place the watering troughs outside the shed wall so that the cows can access it but so it does not drip down into the bedding. Moisture is needed for the activity of the compost bed but too much makes it very difficult to maintain aerobic conditions.

 Also useful would be to have drop down curtains, especially on the side where the heavy weather comes from so that rain can be excluded from reaching the bedding.

In really cold climate, one could employ a really large heat exchange ventilation systems which uses a counter flow system to pass outgoing air past incoming air to keep the heat while exchanging the air.  Such systems are used on as smaller scale in air-tight houses today.

When we talked to the farmer in South Africa who was using this system for Chickens, he mentioned as an aside how disease free his chickens were under this system.  Apparently any pathogens that fall into the bedding are on a hiding to nothing.  The environment is inimical to their survival and they are destroyed by the rich fauna of composters.  Another article I read on cow sheds using this system emphasized the same phenomenon.

To recap, what are the benefits of this system.

* Animal welfare.  The very fact that cows vote with their feet and choose to bed down on the compost in preference to staying out in the cold or going to a straw lined stall shows how beneficial such a system is.  It is highly likely that in such a system, the amount of milk per unit feed would increase as the cows are using less energy to keep warm and are less stressed.

* Nutrient retention.  All the nutrients from the waste products of the cows is held in the compost to be later used to enrich the soil of the farm.  Nitrogen and Sulphur do not go off as gases to be lost to the farm.

* Odor control.  The smell of a well aerated compost is faint and pleasant in great contrast to an anaerobic compost.  The neighbors are not annoyed.

* Disease control.  There are strong indications that diseases are reduced with this system.  It is likely, for instance,  (though not yet reported on) that mastitis would be reduced when the cows bed down on a compost bedding.

Monday, September 4, 2017

Getting into orbit

Disclaimer:  I  ain't no rocked scientist.

But it seems foolish the way were are getting into orbit.  I understand why Elon Musk is going this rout.  He wants technology that is capable of landing on Mars using it's rockets. Returning rockets to earth this way, as he is doing, is a good test ground for eventually landing on mars.  But for others, who are sending payloads into orbit, it seems pretty costly and inefficient.

Very likely I am wrong.  My calculus is rudimentary and I base the following on simple (high school) physics a touch of Skunk Works philosophy*

*The Skunk works  buys everything it can off the shelf and only innovate those parts of a system needed for the particular function it wants to achieve.  They are consistently within budget and beat deadlines.

Why Calculus?  If you want to calculate how far you have gone in a car traveling at a constant velocity you just multiply velocity times time.  For instance, traveling at 50km per hour for two hours, you travel 100km.  Sending a rocket into space gets a tad more complicated.

You have a slightly decreasing gravity as you go into near earth orbit, a rapidly decreasing fuel and oxidizer load as you burn off fuel, a decreasing air resistance as you get higher  but an increasing air resistance as your speed increases.  Calculus allows you to combine  these and other constantly varying factors to ultimately work out, for instance, how much fuel you need to get a given payload into orbit.

While we are talking about complications, there are certain restrictions you have to observe.  You can't accelerate too fast or you may damage your payload (people and instruments).  You also must not achieve too great a speed too soon.  If you do, you will burn up the outer skin of the rocket.  The Black bird, for instance, cruising at an altitude of  85,000ft (16 miles)  at Mach 3 (three times the speed of sound) has it's outer skin heat up to about 300degrees C.  The only reason it survives is that it's skin is made of Titanium rather than an alloy of Aluminum.

This introduces another problem into the mix.  Sometimes it is useful to go to the extreme limit of a problem to get an instinctive feel for it.  For a rocket to get into space it needs it's energy to overcome a number of factors.  It must provide enough thrust to equal the weight of the rocket.  More is needed to accelerate the rocket.  For every kg of rocket weight it lifts by a meter, a kgm of energy is needed (9.8 joules).  More still is needed to overcome air friction.

Lets go to the extreme case and take a rocket that provides just enough thrust to hold it in position.    It is not gaining altitude.  It is expending energy to no useful purpose and the amount of energy equals the rate of energy being expended multiplied by the time it remains stationary.  From this you can see that the faster it accelerates, the less total energy it will need just to support it's weight.  The less energy that is wasted just supporting it's weight, the more energy goes into acceleration.  However the above restraints limit how fast it can accelerate.  All this means it needs more fuel.  Remember this analogy.  It will become important a little further along.

Most rocket ships use an oxidizer, often oxygen itself and a fuel which is often Hydrogen.  Already we are courting disaster.  You either have to hold these gases at very high pressure to have enough on board to do the job or at very cold temperatures so that they liquefy.  In both cases you need very special tanks that weigh a lot compared to the sort of tank that you have in your car for gasoline or diesel fuel.  The high pressures or extremely cold temperatures also cause problems.  If we could get rid of this sort of fuel and oxidizer we would be far better off.

So what is the solution.  Take the first stage of your rocket and strap on four, off the shelf, 747 turbo-fan engines.  The PW4000 develops just under 45metric tons of force.  So four of these = a little under 180 tons.  Lets call it 150 tons to be conservative. Perhaps better still, use blackbird engines which can work at very high altitudes. In either case you are now using the air as an oxidizer just as all jet planes do and your fuel is the relatively benign jet fuel (very similar to kerosene or diesel fuel).  look at the range of these aircraft.  Just on the fuel in their wing tanks, a 747 can fly a third of the way around the globe at around 30,000ft.  Pretty impressive, no?

On second thought, there might be a third type of engine that I am not familiar with that would be better than either of these two.  The regular 747 engine is designed to work best at around 30,000ft and the Black bird engine to work at super sonic speeds.  What we need is an engine that will work at subsonic speeds at very high altitudes.

Whatever engine you decide on, suppose that you don't have enough thrust now to send your rocket straight up.  Lets strap on a pair of wings and take off from a runway.  The shallower the angle of take off, the greater the load for a given amount of thrust.

Why the wings.  Not only do they allow you to lift payloads far greater than the thrust of the engines but also with far less fuel.  Once again an example is useful to get a feel for the problem.  Picture a 747 at cruising altitude neither gaining or loosing altitude.  The thrust it needs and hence the rate of fuel use is far less that if it turned its nose upward and just hung there on its engines.  With or without wings, you still have to lift x kgs up to y meters but the wings, to a large extent support the weight of the payload without needing this huge extra thrust just to support the weight.

So where have we got to so far.

Basically we have a stripped down 747, possibly with a modified wing for lift at high altitude and suitable high altitude engines.  So how much weight have we eliminated.  A 747 can carry 660 passengers in a one class configuration and very conservatively, each passenger weights 100kg.  That is 75kg per person plus 25kg of baggage.  As I said, this is very conservative.  The load carried is therefore 66000kg or 66 tons and we haven't even considered the freight they carry independent of their passengers and all the fittings inside the fuselage needed to accommodate their passengers.  I don't know how much this would amount to all told but it is considerable.  Probably around 100 tons for passengers, freight and all the fittings the passengers require.

So how do we carry the second stage (the first rocket stage) up to high altitude to be launched.  We have three choices.  We can sling the rocket under the plane, carry it on top the way they did with the shuttle when transporting it back to be refitted after it landed or we can carry it inside the fuselage.  The two outside options probably require some reinforcing for the contact points.  The inside option necessitates a bomb bay or an opening ceiling such as the Shuttle had.  As odd as it seems, carrying the rocket on top might be the preferred  option.

So how do we launch.  The mother ship flies toward the equator where the maximum earth rotation boost will be obtained (about 1000mph) gaining altitude as it goes.  When at maximum altitude it turns to face East so that it is traveling in the direction of the earth's rotation.  It puts on full power and does a vomit comet maneuver.  That is to say it pulls up into a parabolic curve at zero gravity or even a slight negative gravity.  At or before the peak, the second stage (first rocket stage) detaches and fires it's rockets.  The mother ship veers out of the way of it's rocket blast.

At this altitude we have lifted the weight of the second stage up, say 100,000ft, gone through by far the greatest part of the atmosphere and given the second stage a speed of, say 1500 mile per hour.  We might be able to get away with some of those off the shelf solid state rockets and further eliminate the problematic hydrogen and oxygen.  Initially, a couple of small canard nose wings might be sufficient to maintain direction.  In the vacuum of space those little nose rockets would maintain direction.  We need to achieve about 18,000 mph.  The solid state rocket shells might then be cut loose or alternatively, they could be configured on the ground to be a useful component for the construction of a space station.

The converted 747 flies (mostly glides) back to base.  It can have another rocket attached be refueled and be back at the launch point  in a few hours.  We could probably launch 4 or 5 rockets each day this way from a single mother ship.

We need costing by professionals far more qualified than I am but it just seems to me that we could get payload into orbit far cheaper than we are doing today.

By the by, whatever happened to the idea of building a space station in the form of a bicycle wheel.  With the appropriate spin, there would be one G at the rim and the astronauts would cease to have the weakening of their muscles and the wasting away of their bones.  If you want to play around with some figures, centripital acceleration equals the square of the peripheral velocity divided by the radius of the circle.  Put this equal to 9.8m per second squared and you can work out the details of your space station.

Electric VW combi, bulli, mini-van

VW is finally going to give us the electric Combi.  Fantastic, but they must keep the faith.

The original Combi was iconic for a number of reasons.

* It was simple compared to other vans.
* It was easy to work on - easily repaired
* It was affordable
* It didn't change its styling from year to year.

It should be not only possible but really easy to produce an electric Combi that excels in all of these.  Styling is simple.  Once it is designed simply don't change it.  This is a vital factor in making a car become iconic.  It also allows better pricing.  It is expensive to re-tool your body presses each year.

Electrics by their nature are far simpler that petrol cars.  Make very very sure that everything that might have to be done on the car is very simple to do.  The engine should be removable by undoing 6 nuts and sliding in a new or reconditioned one.  Batteries should be exceedingly simple to replace (for instance when new technology results in an even better battery).  CV joints should be doable by a modestly competent home mechanic and so forth. Go over the rest of the car (exclusive of the propulsion system) and make sure every part is easy to work on.

And don't put in everything that bumps and squeaks.  We are not looking for luxury in the combi.  Just a good ride in an affordable vehicle which has great range and is inexpensive to maintain.  At the very least, make all the flash options just that.........options.

If your engineers simply can't resist a challenge than get them to work on  a way to clad the whole roof with solar cells such that they all give their full power despite not being co-linear or being partially shaded.

No one expects to be able to drive only on solar.  That is unrealistic but what a nice bonus and a way to get you out of trouble if you have ignored the charge of your battery.  It happens.


Keep the faith and you will sweep the market.   Such a car is not for everyone but many of us want to have a smaller footprint.  Many of us want a car that we are proud to drive.

And for #@%^&; sake, don't make it self driving.  We like to drive.  Besides we don't want to be spied on all the time or worse still have our vehicle hacked and therefore come under the control of  someone else.  Even worse, we don't want the various secret service organizations to be able to decide to drive our car over a cliff or into a tree.  In short, we don't want our car even to be connected to the WWW.

Saturday, August 26, 2017

Restoring our soils

This is a book review of David R. Montgomery's book, Growing a Revolution; Bringing our soils back.  I highly recommend the original.  Besides being a real eye opener, it's a good read.


If you prefer, here is the author talking about the book on Youtube
https://www.youtube.com/watch?v=c4p-kQ6D8aA

Prof. Montgomery has traveled the world and documented the work of farmers far and wide who are using these techniques with amazing results.  Even more amazing is that when there is one of these farms right beside another which uses "conventional methods" and the difference in production is blindingly obvious  even at a casual glance, these so called conventional farmers who are using large inputs of agricultural chemicals, very often  stick with their methods.  Prof Montgomery suggests why this is.

In his book you won't find reports of great research done by the agricultural departments of universities.  No university can afford to do the research that has led to these methods.  As the world becomes more and more of a corporatocracy, and multinationals find ever more inventive ways to avoid taxes, government funds have dried up and almost the only source of funding remaining is from these same tax avoiding companies.

No company is going to fund research that leads to less  of their products being used.  If, for instance, a universities agricultural department is being funded by a producer of Phosphate, they will think twice before even having an independently funded research project on site that will show that you can reduce or dispense (for a time) with more additions of phosphate.

Let me quote a small section from the book.  It regards Rattan Lal, a researcher who went to Africa and worked out methods to improve the agriculture of subsistence farmers.  These methods are right in keeping with what is described in Montomery's book.

"Within two years of his departure from Africa, trees were growing through his experimental plots.  The grand experiment was over.  He'd figured out something that would work for subsistence farmers .  So why were his findings all but ignored?

Funders and aid agencies alike wanted breakthroughs and rapid revolutions, not gradual improvement of the soil.  Commercial interests pushed to develop solutions that could be commodified, they wanted petrochemical products, not practices that anyone could adopt for free,  No modern, forward-looking foundation or agency wanted to hear about mulching or growing a diversity of crops.  Such simple answers did not - and still don't - fit the technophilic narrative of progress."

No, what is needed is demo farms in as many districts as possible who are willing to try out these methods, on at least  one of their fields and keep at it for at least three years.

The type of farming mentioned in the book, leads to  a greatly reduced use of fertilizer, pesticides, herbicides and fuel. Note I said reduced, not eliminated.

What is reported in Growing a Revolution is the work of many farmers around the world, usually with no connection with each other.  These farmers would qualify, by any definition, as true scientists, trying things and recording their results and trying again.  There are variations on a theme but what is also amazing is that all these farmers have converged on the same basic realizations.  It has taken many of these farmers decades to come to these methodologies.  Mr Mongomery's book is an attempt to smooth the way for other farmers so they don't have to go through the same lengthly process.

What then does Mr Montgomery claim that this sort of farming achieves.  Actually, I should rephrase that.  What has he observed that farmers around the world are achieving with these methods.  And notice the emphasis on methods in the plural.  While each method shows some positive results, these methods only truly revolutionize farming when used together. First the results of this type of farming.

Results of this 'new'  type of farming


#  Reduced  inputs including diesel, chemical fertilizers pesticides and herbicides resulting in greater profits even if yields only match "conventional*" farming.  In fact, yields more often than not, rapidly (in a few short years), exceed those of chemical farming.  Profit equals production minus inputs.

* We now think of farming with chemical inputs as conventional since we are used to seeing this type of farming but it is actually a very new way of farming. When we get on to methods, you will see that many of the methods are very old school but modified by recent insights into the biology of soils. So called conventional farming necessitates large amounts of fossil fuel just to produce the materials used in farming.  Add to this the fuel to run the tractor and you are right in the middle of unsustainability.  Reducing these inputs has to be a good thing from a number of points of view.

#  Increased infiltration of water into the soil and the  corollary, reduced or eliminated  surface run off, thus stopping the export of our soils into the ocean. The other corollary of more infiltration, especially with reduced evaporation is less dependence on irrigation and in the case of dry land farming (without irrigation) the difference between a crop and no crop.

# Greatly reduced export of  soil into the streams if there is a "weather bomb" and runoff does occur.

# Elimination of wind erosion

#  Greater drought resistance since rain has infiltrated and soils are always protected by a cover crop and/or mulch, which decreases evaporation.

#  Greater flood resistance for the whole catchment since the soils can take up much more water without sending it straight down into the nearest water way.  If a whole catchment of farmers adopted these methods, flood peaks down stream would greatly decrease and with it, the damage to downstream property.  Once the water is underground, it flows much more slowly toward the sea. Not only are peak  flows  reduced but low water flows are increased as this water slowly percolates back into the river systems.

# Water purified before flowing into the streams.  When water flows through a rich organic soil containing reduced carbon*, the fauna of the organic soil scavenges nutrients from the water, reducing the amount of P and N entering the streams.  In addition, pathogens don't have a chance when they enter a rich soil ecology.

* Reduced in the chemical sense as opposed to oxidized.  Reduced carbon is an energy source which plays the same role that sunshine does above ground.

#  Nutrients held in the soil in a form which is accessible to the next crop rather than exporting them to the nearest stream via the ground water. Streams flow clear again and if adopted widely, dead zones at the mouth of rivers from eutrophication would be a thing of the past. As a result, aquatic life in the streams recovers.  Salmon and trout prosper.

#  Weeds much less of a problem despite  the use of no-till agriculture and reduced or eliminated use of herbicides.

#  It is believed here in New Zealand that on well drained soils, when a cow urinates, it goes right through the soil into the water table and hence into nearby streams. Organic material is a sponge which will soak up liquid, whether water or urine.  If the organic material increases, not only at the surface but also at deeper and deeper levels of the soil, so much the better.  The following methods increase organic material throughout the soil, shallow and deep.  Once the liquid is held in the soil, the fauna in the soil scavenges the nutrients from it.

So what are the methods David has observed which are creating this revolution.

Methods

You may have noticed that I have called this a new way of farming.  As I mentioned it is not new methods but the adaptation of methods which were used before the advent of chemical inputs but  with a modern twist in light of modern knowledge. These farmers still use chemical fertilizer where necessary.  This so called 'conservation agriculture' is not a religion but a pragmatic approach to farming.

Crop rotation
Sound familiar??  .  No surprises here except he has observed farmers who are using a better way of crop rotation.  If you only plant wheat, this is the worst case scenario.  If you rotate wheat and, a legume in alternate years, this is better.  If you adopt a three way rotation of, say wheat, corn, soy beans, better still but the best system is to rotate as many different crops as is practical and in random time patterns.  This type of rotation confounds the pests.  For instance use wheat barley and oats as your grain crops interspersed with soya, corn and peas.

Note  Corn is a C4 plant and hence produces a lot of organic material which can be cycled into the soil for the soil organisms.

Many pests are crop specific.  Planting the same crop in the ground year after year allows them to build up in the soil.  Even alternating crops in a two crop system will cause the pests to adapt to this simple system.  You develop a nematode or stem weevil, for instance, that can hold out for a year until the favored crop is returned to the field. A more random schedule of rotation and longer times between the same crop is very hard on crop pests. 

Cover crops
As soon as the summer cash crop is harvested, a cover crop is sown.  The stover from the cash crop is left in the field, preferably rolled into the ground. In locations where there are harsh winters, the cover crop will be killed by the frost.  In warmer climes, it is rolled into the soil before it sets seeds*.  The frost killed cover crop is rolled into the ground in the spring in the same pass in which the cash crop is planted (direct drilled) into this bed of mulch. The best candidate for a cover crop is a mix of 8 or more different species including:

   * The most effective roller he has seen has projecting steel flat bar in a chevron or diamond pattern.  It chops up and pushes the cover crop into the ground.  It all can be done with one pass of the tractor as the cover crop is rolled into the ground and the next cash crop sowed right into the mulch layer created. The cash crop comes up and shades the soil and any weeds that remain. As the years go by, weeds become less and less of a problem.  As much organic matter from both cash and cover crops is left in the field on the surface of the soil.
 
Plants in the cover crop include:

# a deep rooter to scavenge nutrients from down deep and to provide a root system that as it decomposes, leaves passage ways for water and air to reach deeper levels.  This decomposing organic material will also hold water better than pure mineral soil, making it available to future crops.  If cows are grazed on the fields, there may be a problem with their large urine output.  If it goes down into the soil and into the ground water it can flow to the nearest stream.  With lots of organic matter, both shallow and deep, the liquid is soaked up giving the soil organisms time to convert this source of Nitrogen* into biomass.

* We had a major kerfuffle here in New Zealand about indoor dairy farms.  As usual the greenies went off half cocked and dismissed them out of hand.  I don't say that indoor farms are always good for animals.  Some can be really horrific.  The devil is in the detail.  One advantage of wholly or partial indoor farms is that you have almost complete control of the waste products that can then be applied to the soil when and in what quantities are most effective and hence least polluting.  When applied this way there is little or no pollution since the pasture takes up the nutrients.  In this connection see Composting barns.

# a shallow rooter to provide a root network holding the surface soil together and a source of organic carbon and nutrients as it slowly decomposes.

# a nitrogen fixer to add nitrogen to the soil

# a nitrogen user (as  all plants are).  They scavenge the left over nitrogen to be released gradually next season as they decompose.

# a tuber (radish for instance) which as it decomposes leaves large tunnels l for water to percolate down into the soil.  The decomposing tubers feed the soil life and adds structure to the soil.  Many tubers have very deep roots as well.

A common function of most cover crops (not brassicas apparently)  is that they exude high energy materials from their roots into the soil.  These feed the saprophytes.  Saprophytes not only give structure to the soil but  are able to mobilize nutrients that are not available to plant roots and convert them into a form that the plants can use (notably P). They also bring nutrients from outside the root zone of the plant.

The exudates also feed the microbiome which are in turn consumed by earth worms.  The worms themselves are a link in mineralizing* nutrients into a form that can be used by plants.  In addition, they make burrows which  increases water infiltration and allow oxygen** to reach the roots of the plants.

Green plants don't use organic matter.  It must be broken down into a soluble, mineralized form that dissolves in the soil water.  Plant scientists call this process mineralization.

** With a few notable exceptions, plants do not pass oxygen from their leaves down into their roots.  Most need air around their roots to survive.  Worms also provide this service.  Incidentally, if you dig in soil that has been regularly plowed for years, you will be hard pressed to find any earth worms.  After a few years of the type of farming, mentioned in Montomery's book, worms will be back in force.

Different climates and soil types will need different mixes of cover crop species.  This is a rich area for research in working out the best mix of species for specific areas.

No Till
David observes that the plow back into antiquity has probably been a major cause of the destruction of soils.  This is very visible in areas where the Greeks and the Romans held sway.  Much of this land is bare rock.  More recently it destroyed the soils of America from the eastern seaboard to the great plains.  We mustn't be too hard on the plow, though.  It may be part of the reason that we haven't already headed into a new glacial period due to the huge amount of carbon that was released from the soil into the air*.  Now we have found another way of keeping atmospheric carbon up and can afford to adopt methods that return the carbon to the soil.  We are now in danger of going too far the other way and putting far too much carbon into the air for our own good. Sequestering some of this into the soil would be a good thing.
*See the fantastic book by William F. Ruddiman, Plows, Plagues and Petroleum

No plowing is done.  Seeds are planted by direct drilling.  At most a very shallow groove is made in the soil to plant the seeds and if chemical fertilizer is used, it is placed in small doses near the seeds, not broad-casted over the whole field.  Farmers who are adopting these methods are finding that much less or sometimes, no chemical nutrients are needed.

Phosphorous, for instance, in their fields is mobilized from the locked up P in the soil by saprophytes and Nitrogen is scavenged by the cover crops and held in a slow release form (their bodies) for the next cash crop. It is also supplied by the nitrogen fixer in the cover crop.

 This doesn't mean that no chemical fertilizers are ever used but they are used as needed.  If, for instance, your soil was found to be deficient in, say, cobalt, clearly you would apply a  cobalt fertilizer to provide for your plants and/or animals.  This is not organic farming.  It is not so called 'conventional' farming.  It is conservation farming.  It is not a religion but a  science in which you do what works.

Clearly, if you are continually removing crops from your land, you will need, at some point, an input of the removed elements.  There is nothing wrong with using chemical fertilizers but you don't want your  nutrients to be continually locked up by the soil in a form that the plants can not get at.  This is expensive.  You also don't want your nutrients to seep down below the root zone and be washed into the nearby stream.   Nitrogen can be provided from the air by a nitrogen fixer.  Your input of chemical fertilizer is  reduced and is applied only as it is needed and this shows in your bottom line.

Often, in soils where super phosphate has been used over the years, the soil has a huge reserve of Phosphate but it is all locked up.

The above are the three main methods, namely no till, cover crops and random crop rotation.  In addition there are two more where appropriate.

Grazing
Again not a new system but an old system with a new twist. It is used by some of these farmers. Both crop stubble and cover crops can be grazed and turned into manure and urine which is very good for the soil.  If grazing is used, no roller is needed.  Some of the vegetation is trampled into the surface of the soil which acts as mulch and provides food to feed the soil organisms. The rest is deposited as droppings and urine.  The system that seems most successful is to graze very hard, very infrequently.  Cows, for instance are put on a paddock at a density that finishes all the fodder in in one day and then this area is not grazed again for a year.  This system may have been inspired by a TED talk by Allan Savory on his work in Africa.  This TED talk is a revelation in itself.

No farm, however, can afford to break the farm into 365 small paddocks with fences.  Instead mobile electric fences work very well to allow grazers access to a limited area and exclude them from both the as-yet-to-be-grazed area and the already-grazed area.  One uses a front and a back electric fence. Many farmers in New Zealand already use this method.  There may be places where you would let the grazers in more than once per year but the same principle still holds.  Very heavy grazing very infrequently.

Terra Preta 
In warm areas with soil above about 25 degrees C, humus which holds nutrients and gives structure to the soil, breaks down and goes into the atmosphere. Unless nutrients are taken up rapidly by, say, an overlying jungle the nutrients are rapidly lost to the system.  When a tropical jungle is cleared, at most a couple of crops can be grown before the soil is exhausted and the farmer than resorts to chemicals which  finish the damage.

It has been observed, though, that there are exceptionally good soils in some tropical areas, often along major rivers.  These are areas where the locals have incorporated char into the soil from partially burnt bones and plant material.  Char has a three functions.  It has no nutritive value to the plants what so ever but it does provide niches  where the microbiome can live*.

* The organisms in the micro-fauna of a soil usually live in colonies attached to a substrate.  They are not free living like, for instance, phytoplankton in the oceans.  Charcoal provides ideal surfaces and hidy-holes for such organisms and lasts for centuries in the soil.

If you raise chickens you may be familiar with something similar.  If you have a lot of chickens in a yard, before long they will have eaten every bit of green that they find at all palatable.  So you set up a bunch of cages and plant their favorite green inside.  They can only get to the outside leaves so as the plant grows, the chickens crop off the outside but the plant itself is protected and continues to provide greens for the chickens.  Charcoal is very porous and in the soil serves a similar function.

Charcoal, though, has another function.  It can adsorb nutrients on its surface when they are available and release them when in low concentrations in the soil.  Char with respect to nutrients is a little like the hemoglobin in our blood with respect to Oxygen.  In both cases the substance in question is taken up easily when available and released when not.  In cooler climes, humus serves this purpose.

Char is probably not a practical option in commercial farming until  and unless we start producing it in large quantities at a feasible price.  One good thing, though about char is that it lasts for a very very long time in the soil.  In a home garden, it is very practical.  All you need to produce char is a 45gal drum.


Note:1  I have just read an article on composting barns by Keith Woodford. This technology would fit in exceedingly well with what Prof Montgomery has reported on.  Composting barns capture all the nutrients, including nitrogen, contained in the poop and piss of the animals,  when they are in the barn. This includes whatever the cows produce at night and when sheltering from inclement weather. When spread on the land it reduces the amount of bought fertilizer needed, and is applied when, and at a rate that most benefits the pasture and hence causes the least pollution (like zero). Compost also provides reduced (in a chemical sense) carbon which provides energy for the soil organisms.

Note:2  Finally,* (Oct 2017) one of our farms has installed a biogas generator to utilize the effluent the cows drop in the milking shed.   The biogas is used to run a motor connected to a generator.  More than enough power is produced to run the milking shed.  Instead of wasting the heat from the cooling of the motor, it is used to heat the water needed in the milking shed**.  A biogas generator only removes C and H from the effluent so, as with composting barns, the effluent from the biogass generator contains all the nutrients in the original poop, piss and spilt milk and can be spread on the pasture when, and at the appropriate rate that benefits the grass and causes no pollution.

*  John Fry of Rodesia sorted out biogas generation from animal waste back in the 1950's

 **  When you utilize the heat from a motor/generator running on biogas,, as well as producing more electricity than you use in the shed,  efficiencies of around 75% are achieved.

Note 3  If you were to incorporate sawdust into your soil, and then plant your vegies, you would find that your plants would hardly grow at all.  What is happening here.  The cellulose in wood is simply a chain of sugar molecules which are linked in such a way to make them unavailable to multi-cellular animals.  On the other hand there are many bacteria which produce cellulaze, the enzyme that can break down cellulose and hence, can access this supply of energy and carbon.  With an input of sawdust, soil organisms will flourish but the nutrients will be locked up in the biomass (bodies) of the soil organisms.  As soil organisms eat each other, they incorporate around 10% of the biomass into their own bodies and excrete the rest.  As long as there is reduced cellulose around, the primary producers (in the soil, this is the microfauna that produces cellulaze) will utilize the waste and build it up into their bodies.   As the source of cellulose runs out, the various soil organisms continue to eat each other and release nutrients. At this point your vegies would do just fine.  Soil organaisms  are giving back the nutrients they captured and there isn't enough reduced carbon in the soil now for the mineralized nutrients to be recaptured by the primary producers.


Addendum

Carbon credits

If the government is playing fair with farmers, the farmer should be able to receive a nice carbon credit for switching to this type of farming.  What is first needed is a survey of your farm to determine what is the carbon content of your soil before you change your methods.  You can do this yourself at home if you have a reasonably sensitive balance.  Of course you need an official analysis if you want to pressure the government to play fair.   If I remember my chemistry, the procedure is something like this.


You take a sample of soil, preferably with a corer or a post hole digger that goes down to mineral soil.  You note the depth to which you took the sample and the area of the surface of the core.  A = πr2   (pi r squared)

Thoroughly mix the soil and take an appropriate size sample.

Treat the soil with an acid such as HCl or H2SO4 (battery acid).  This converts carbonates to Chlorides or Sulphates.  Otherwise, when you heat the soil later, the carbonates convert to oxides and it looks as if you have more organic matter than is actually in the soil. When you treat the soil with acid it will likely bubble.  This is the lime giving off it's carbon dioxide.

You dry your sub sample to constant weight at just over 100 degrees C.  ie, you dry it, weigh it, and dry it again.  If the weight remains the same, you go to the next step.  If not, dry again until two subsequent weights are the same.

Put your sample in a porcelain type container that has been dried and fired to constant weight and heat it in the oven to about 500 degrees C.  Start in a closed container but finish with the container open.  You can get appropriate containers from any chemical supply shop.

Burn to constant weight.  The difference between the start and the finish is the amount of dry organic matter in your soil. Very close to 50% of this is carbon You can then calculate the amount of carbon in the upper level of soil down to the depth you cored.  You can also work out the percentage in your soil and the carbon content per hectare.  If you want, you can convert this to the Carbon dioxide equivalent by multiplying the carbon by 44/12 or the weight difference (total dry organic matter) by 22/12.   This is the amount of Carbon dioxide you have sequestered from the air.

Saturday, June 17, 2017

Self driving cars



Are we really sure that we want self driving cars.  In fact, are we sure we want a car that is even connected to the Internet.  There are some pretty strong arguments against both self driving cars and against cars which are connected to the Internet (done so that software updates can automatically be fed into the car computer).

Just recently there have been some pretty serious hacks.  The NHS (National Heath service of the UK) was taken down and here in New Zealand we just had a program on our National Radio about the hacking of electrical power line companies.  You would have thought that if there were systems with the very best of protection, it would be these.  Perhaps they did have excellent protection but were hacked anyway.

Update  Today (17 Oct 2017) WiFi was hacked.  Sheeeesh!!

Imagine the chaos if we had even 10% of our cars connected to the Internet when someone managed to hack the system.

Then there is the secret services of the United States and the so called 5 Eyes.  In America it is illegal for these institutions to spy on American citizens but they do it anyway.  The  hoover up every phone call and e-mail from America and from the rest of the world.  Even having a car which is connected to the internet, never mind self driving, gives these institutions yet another window into the private life of all of us.  And don't give me the argument that if you are not doing anything wrong you have nothing to fear.  That argument is so discredited that it doesn't even justify wasting a paragraph explaining the  fallacy.


Suppose, for the sake of the argument I want a new software program for the electric car I am driving and my car is not on the internet.  No problem.  I will go to my home computer, download the upgrade on to a flash drive, take it to my car and plug it in to the flash drive socket provided.  Besides, I may want to wait a year to let the early adapters test it out before installing it.  The computer world if rife with new computer programs being full of glitches.

Suppose I need navigation.  I will simply take my cell phone and put it on the Velcro patch on the dash board.
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As for self driving, let me ink out a scenario for you.
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You have a daughter - the apple of your eye.  You insisted that she learn to drive on a gear shift car since you are a little old fashion and value the old skills.  However since she got her license, she has never driven.  You gave her a self driving car for her birthday and she loves it. (no wonder) Today she is off to a show in the next town with her boyfriend.  ETA 30 minutes.  What do you think she is doing for that half hour.  

She is snogging in the back seat with her boyfriend going at highway speed  when some sort of computer glitch or hack demands that she take the wheel and manage the brakes and accelerator.  It would be chaotic enough if she was sitting in the drivers seat with her hands off the wheel.  You fill in the rest.

Add to this the ability the secret services will have to send a car into oncoming traffic, over a cliff or into a tree.  You think I am exaggerating.  Look at the drone programs exposed by Manning.  They took shots at a suspected terrorist while he was surrounded by civilians.  Secret services are amoral and we don't need to give them more tools to do what they want.  What's that you say?  They don't operate on their home soil.  Give me a break!!!

And one further point.  With self driving cars and trucks, we put yet another tranche of workers out of work.  These are folks that will never be engineers, scientists or lawyers and we need work for them as well.  Economists seem to always ignore one basic fact of the economy.  The most important factor is the rate that wealth circulates through the economy, not the amount of dollars available.  Work through the implications (already demonstrated) of putting yet more people out of work.

It simply leads to wealth being more and more  concentrated in the hands of the very few uber rich and less circulating in the economy.  We are rapidly getting to the point that less and less people will be able to buy the products produced in the factories.  One good effect of this is that it cuts into inflation.  That may help to explain our present situation (2017). 

I have a strong feeling that an electric car manufacturer who advertises that his cars are not self driving and have no connection to the Internet would have a strong selling point.