When it Comes to Soybeans--Dig Deep

By Tara Weaver
February 9, 1999

Farmers can boost their soybean yields in low-rainfall areas by tilling clay soils to a depth of 12 to 16 inches in the fall when the soil is dry, according to Agricultural Research Service (ARS) scientists.

This tillage practice, called subsoiling, could particularly help farmers in the Mid-South region, where many soybean crops don’t yield enough to make a decent profit because clay-laden soils block water from reaching plant roots.

Subsoiling allows water to infiltrate deeper into the soil where it can be stored for thirsty roots. This additional water-holding capacity contributes to higher yields, and environmental bonuses--less runoff, less soil erosion, and less sedimentation in lakes and streams.

ARS scientists at the Application and Production Technology Research Unit in Stoneville, Miss., conducted a five-year subsoiling study, with both optimum and extremely dry seasonal weather. They found soybeans planted in this system produced, on average, 43 bushels per acre compared to 29 bushels per acre under the conventional system with no irrigation.

Subsoiling also produced yields similar to those produced in conventional systems with irrigation--43 versus 45 bushels per acre. Net returns were $129 an acre from nonirrigated deep tillage compared to $48 an acre from nonirrigated conventional production, and $83 an acre from irrigated conventional production.

ARS researchers say this practice is compatible with conservation tillage practices, since subsoiling doesn’t destroy crop residues on the surface and is not necessarily required every year.

A story about this research appears in the February issue of ARS' Agricultural Research magazine. The story is also on the World Wide Web at:

/is/AR/archive/feb99/deep0299.htm

Scientific contact: Richard A. Wesley, ARS Application and Production Technology Research Unit, Stoneville, Miss., phone (601) 686-5354, fax (601) 686-5372, rwesley@ag.gov.