Securing carbon in our soil

Everybody knows plants store carbon. But soils do too.

That’s the idea behind organic no-till farming, a cultivation technique that could dramatically increase soil carbon storage across the globe.

Research has shown organic farming methods sequester more carbon per acre than fossil fuel-based conventional methods. While scientists are still fleshing out the reasons for this, one likely cause is the increased level of mycorrhizal fungi in organically managed plots. These microscopic fungi literally help “glue” soil particles together, which traps organic carbon, nutrients, and water in the soil for the long haul.

Similarly, no-till farming preserves soil carbon storage through the thick crop root systems that develop when tillage is dramatically reduced. The combination of the two methods is now being studied by the Rodale Institute for its potential to produce even more climate benefits.

The early results are striking: compared to conventional farming techniques, which result in 300 lbs of carbon emissions per acre each year, Rodale’s research (pdf) suggests that organic no-till farming combined with utilizing compost as a natural fertilizer could store over a ton of carbon per acre per year in the ground.

The best part? Crop yields are likely to remain the same or even increase under organic no-till management. Rodale’s long-term comparison study of organic and conventional methods showed no difference in yields between the two farming techniques in normal years, and increased yields in organic plots during drought years (thanks to all those mycorrhizal fungi holding water and carbon in long-term storage). The variety of other benefits generated by organic no-till farming — from reducing nutrient runoff and erosion to decreasing fuel and fertilizer cost — are icing on the cake.

P.S. No-till agriculture has also played a somewhat controversial role in the carbon market. We’ll have some thoughts on those issues next week.

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nicole

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  1. Grandpa - March 31, 2009

    It is generally true that organic growing practices reduce yield which leads to higher prices and larger acerage cultivated. Make sure your footprint incorporates carbon lost in organic practice. I like your blog.

  2. Jay - March 31, 2009

    No-till farming also greatly reduces soil erosion from wind and rain. Even if you do have lower yields in the short run, the ordinary approach of tilling and using chemical fumigants and fertilizers is so destructive of the soil that long-term cost/benefit analysis ought to favor soil-conserving methods. There is also the possibility of using bio-char to enrich the soil and sequester carbon.

  3. Dave - April 1, 2009

    Over the past 8 years I have steadily built up the soil in my urban lot from bare clay-rich fill (no topsoil) by adding numerous bags of leaves from up and down my street. I shred them with the lawn mower and have built up a 6-10 inch layer of very rich organic soil for vegetable gardening. Every once in a while I turn and dig it in, but mostly I just let the earthworms do the mixing. When a tree in my yard died, we saved the chipped branches for use on the property in landscape. I try to return all the bio-material from my property, back to the property. As well as bringing home coffee grounds from the office, and composting our household vegetable waste and garden trimmings.
    I am certain the fungi play an integral role in soil health and soil chemistry, and that enriching the carbon content in this way mimics what would have been present in a rich topsoil of a succession forest that may have been present in this area before human “development” came along.
    The biochar possibilities for fixing carbon on the scale of 500-1000 years intrigue me. We need to study and learn whether it may be part of the solution to restoring fixed carbon to the soil system, in temperate latitudes as well as the tropics where “terra preta” originated. Ideally methods must be developed to practice this carbonization or charring, simply at small as well as large scales and without causing air pollution.
    The thing about no-till farming at the large scale is it uses herbicides to kill and suppress weeds (instead of the plow, harrow, and inter-row tiller-cultivator machines). I’m not interested in increasing the loading of such inputs on the soils of my watershed.
    My own gardening approach is intended to be chemical free, using hand-weeding and composting, and based loosely on my understanding of “permaculture” concepts– edible fruit trees and shrubs, local varieties of grapes, native plants, as well as vegetables including perennial strawberries, garlic, and heirloom tomatoes. I have selected native species for planting trees and shrubs on site, to help maintain and restore the local ecological quality in my watershed.

  4. lonna Richmond - April 1, 2009

    if you’re interested in biochar, read the recent article in ORION written by Bill McKibben. i think it might answer some of your questions. it’s the issue with the girl lying on her horse (last month’s maybe)

  5. Peter H - April 2, 2009

    Biochar – a google search will add more info, or also search on terra preta…..that is the Amazonian soil supposedly built via agrichar or biochar [ terms get to be used interchangeably]
    NOTE – biochar can be made by pyrolysis of organic residuals – and produce a syngas that can be used to produce energy. Think of it as somewhat similar to producing charcoal from wood.

  6. Peter H - April 3, 2009

    Healthy soil is the real need. When I was in graduate ag science school the use of rotations and pasture ley phases were the norm, and are in many parts of the world still. Think Australia, Africa, Argentina. That pasture ley phase builds up the organic matter as well as all sorts of microbial “helpers”. Then using conservation tillage helps keep the organic matter there, in the soil.
    Getting back to higher levels of organic matter in soil……and NOT necessarily organic production per se is probably the real need. Yes, there is a place for certified organic production, but I beg to differ in that It is unlikely to feed the masses.
    By the way……..countries such as India and parts of Africa and Asia are rapidly embracing GM crops especially cotton. Better yields, less work [=labour] and less agrochemicals and better yields. For the local farmers it has been a bit of a “no -brainer”.

  7. Tom Harrison - April 3, 2009

    One clarification — no-till farming is not necessarily organic, in fact my reading suggests that use of fertilizers and pesticides is typical. This is not to say that no-till is bad in any way (on the contrary, it seems like a win-win-win).

  8. Tom - April 8, 2009

    Tom Harrison is right. No till was originally adopted for conventional farming to reduce crop preparation and maintenance.
    The benefits of increasing organic matter are immense, especially by the use of a compost management system. Most of our recycling is urban with small outflows from urbs to rural areas. The amount of organics which could be recycled into cropland would never cover all the farms.
    By my calculations for North Carolina, approx. 4% of cropland could be fed per year if all organic waste was composted. Yet our well managed composting programs are ignored and not funded for more popular and visible demonstrations.
    Paper comes from rural forests. Food waste comes from farms. Waste lumber comes from farmland. The waste we flush comes from food from farms. These categories comprise about 50% of all wastes handled in cities. Lets put some of that back into farmland and make the trillions of bacteria & fungi our unseen employees to keep us and out planet healthy.
    Rodale is finally focusing research on agriculture which can benefit the scale of farming which feeds us. Amen.