Thursday, November 3, 2011


The soybeans have been harvested. All that is left on our fields is a scattering of green dandelion plants, a few drifts of cream colored soybeans where the combine missed the truck, and the shredded remains of the soybean plants. Almost nothing.

Experts recommend leaving 30% of the soil surface covered with vegetable matter over the winter. Our fields look much barer than that and they haven’t been tilled. The seed was drilled in last spring, disturbing the soil as little as possible. But soybeans as a crop leave so little behind that we may run into problems with wind erosion this winter until we get snow cover, and we may get water erosion in the spring from snow melt. Of course, we won’t get nearly as much erosion as if we’d actually broken the ground this fall.

The Land Stewardship Newsletter reports experiments showing erosion of no-till soybean fields on a slope in Iowa. Because of heavy rains, the farmer lost 11 tons of topsoil per acre in 2008. When he planted 10% of the field to strips of native prairie grass, his loss of topsoil dropped to hundreds of pounds per acre.

Our fields are all hills. This summer’s experiment with soybeans reminded me of why we try to keep them in pasture and alfalfa. We’ve planted two small fields to native prairie grasses, but in the future, we may look at planting strips of prairie in our other fields. And for the present, we’ll hope for early snow cover to slow wind erosion and a gradual melt in the spring to slow water erosion.

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