Mike Kiely commentary on soils

This post is responding to my post in April.

Michael Kiely said...

Good to see agriculture getting some attention. A few facts from Australia, which has many advanced 'carbon farmers' sequestering carbon dioxide via native perennial grasses, shrubs and trees: 1. If the world stopped emitting CO2 today there is already enough up there to drive us through the 2°C limit into climate chaos. 2. Only photosynthesis can extract the 'legacy load' of 200 years worth of emissions. 3. It would require 7 planet the size of Earth entirely covered in forests that never died or fell down or burned to do the job. 4. An acre of pasture can hold more carbon than an acre of forest. 5. Soil already holds 1500GT of Carbon vs 750GT held in the Air and 650GT in Vegetation. 6. Farmland (mainly pasture) covers 65% of the landmass of the Earth. 7. A change in land management from conventional farming to carbon farming is easy when farmers can trade the credits for the carbon they store in their soils. 8. Farming techniques that capture and store carbon stimulate soil biology and restore health to soils, waterways, and farmland ecologies. Biodiversity increases. Resistance to pests increases. Soil productivity increases. Reliance on chemical inputs falls. Profits rise. 9. Life's beautiful.

July 5, 2007 12:51 AM

I am personally not convinced that all pasture land holds more carbon than all woodland although that is certainly true in selected cases. Unfortunately, most original grassland has been plowed and a lot of the carbon bank has been released. The most egregious example of this is the area of the buffalo commons in western North America. It would actually be nice to see extensive carbon measurement on soils done on a global scale so as to establish benchmarks.

A quick review of he literature reveals that that is not so easy yet. Which means that there is currently a lot of educated guessing going on.

Woodland has a potential to ultimately store fifty to one hundred tons of carbon for every acre without been clever about carbonization. We are referring to temperate woodlands. Dry land environments are not nearly so cooperative, although the tropics can easily double these figures.

Agricultural soils usually deteriorate down to a layer that is perhaps several inches in thickness for a number of reasons, but mostly to do with the shallow root systems of the annuals used as our primary crops. I grew up with a working six inches of soil were once stood a maple forest that certainly carried a ton of carbon for every tree. This includes the root ball.

In all likelihood the soil itself still contains similar amounts of carbon as the original forest soils although the science is indicating a 35% reduction. What is missing is the tree itself that drew up nutrients from deep down and dumped them every year onto the surface. The elimination of the tree's root system then shrank the soil layer.

One needs to be reminded that the tallest and largest trees(Douglas firs and the like) on the planet grow in the mountains on which soil cover is often negligible. We can have our cake and eat it too by the simple expedient of promoting silviculture on waste and marginal land and employing carbonization to enhance crop lands.

Corn culture's bright furure

The one thing that emerges from our analysis of the implementation of carbonization for soil enhancement is the crucial fit of corn into the general process. This actually comes as a bit of a surprise.

My expectation for plant waste on cropland was very low. In fact, for virtually every conceivable crop, the waste production is at best around one ton per acre. That goes for straws of all kinds. Other types of plant wastes are best plowed back into the field. Carbonization would reduce this down to a couple of hundred pounds.

Corn however produces up to twenty tons per acre which can be carbonized down to a ton of material. In other words, we can count on corn theoretically delivering a ton of carbon into the soil every year. This comes straight out of the atmosphere in one growing season.

It is immediately possible to understand how the black soils in the Amazon were created over hundreds of years. Corn stalks produced the raw material rather than local wood supplies. The farmers likely windrowed the drying stalks in one direction creating a long bundle, perhaps three feet across and the length of the field. These windrows would be twenty feet apart.

This would be tightly packed. The farmers could then shovel on a layer of dirt to seal in the stalks. thereupon the windrows would be ignited and allowed to burn through, carbonizing and reducing the material. After it had cooled down, or more likely at the beginning of the next growing season, the windrows would be pulled apart and spread back over the rest of the field.

This was well within the constraints imposed on the indigenous inhabitants who lived there. The only surprise is that it was never adopted throughout the Americas where similar but lesser soil leaching problems existed in some form or the other. It could be simply that they never linked this directly to soil fertility.

So we have a principal crop that happily sequesters one ton of carbon every year and a modern efficient carbonization process in our incinerators that is easy to use. And the majority of the nutrients are returned to the topsoil in a slow release form. Combining this with an integrated woodlot management system that draws additional nutrients from deep in the earth and we may even achieve 100% sustainability for all former woodland and tropical soils The fact that this was done in the middle of the Amazon for hundreds of years is a pretty good affirmation.

This is actually a pretty amazing discovery. We have a protocol thats fits with established agricultural practice seamlessly and provides for the efficient management of wastelands in direct support of this practice. And it can be mandated and implemented by governmental agency with an expectation of eventual profit by way of a share in wood sales. It also appears to be workable in all but the most arid ecosystems where we should not be anyway until we can harvest water from the athmosphere.

We can also predict that the farmland can achieve a much higher rate of utilization than currently considered feasible. In practice this will not happen since we need other crops and we want to also enhance the soil with other material. However, using a technique that largely prevents the nutrient load from been quickly lost to depth is a major improvement that permits the creation of richer soils over time.

Most farmers will view a yield gain with the elimination of chemical fertilization as an impossible objective. This protocol says otherwise.