Reduce tillage to increase soil organic matter

Farm and Ranch July 5, 2011 If you want to increase your soil organic matter you need to reduce the number of tillage passes you make in a field. That was the message Ann Kennedy with the Agricultural Research Service at Pullman delivered to farmers attending the recent Washington State University Lind Field Day.

Kennedy said in a dryland summer fallow region like Lind, Washington there used to be two percent organic matter down to six inches. Now, she says in some cases there is only ½ of one percent organic matter left in the soil, not enough to provide adequate plant nutrition or hold the soil.

Kennedy: “So we need to something about reducing our tillage passes so that we build up the organic matter levels. We can disturb the soil a certain amount. We don’t necessarily need to go totally no-till to build up organic matter. We can use a two-pass system. A one-pass system, maybe even a three-pass system and will still get over time, and it takes a long time, we’ll get organic matter buildup, which is extremely important for our soils so that they continue to grow these wonderful crops that we grow around here.”

Tillage mixes the residue with the soil and Kennedy says the decomposition microbes go on a feeding frenzy.

Kennedy: “Instead of slowly digesting it into organic matter they actually give off too much CO2. And more of the carbon in that residue goes into the air instead of into the soil.”

That’s why Kennedy says do fewer and slower tillage passes.

Kennedy: “We want to keep the microbes happy but we don‘t want them to pig out on all that wonderful residue.”

I’m Bob Hoff and that’s the Northwest Farm and Ranch Report on Northwest Aginfo Net.

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