Farmers can boost their soybean yields by tilling clay soils to a depth of 12 to 16 inches in the fall when the soil is dry. 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. Scientists conducted a 5-year subsoiling study with both optimum and extremely dry seasonal weather. They found soybeans planted in this system on Tunica clay (clay over loam) 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 obtained with conventional systems with irrigation, at 43 bushels per acre versus 45. 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.
Application and Production Technology Research Unit, Stoneville, MS
Richard A. Wesley, (601) 686-5354.

Good news for farmers of steep, hilly regions of the United States: No-till farming will improve yields of silage corn, according to results from three years of ARS field experiments in Appalachia. No-till has an advantage over conventional tillage in hilly lands because it reduces soil erosion and requires less energy. The scientists compared no-till and conventional tillage—using a range of application rates for phosphorus fertilizer—to produce silage corn, which is grown for livestock feed. They found that dry matter yields, root length per plant and root density were higher under no-till. The increased root growth and density under no-till may account for the higher dry matter yield. Plant uptake of nutrients—except potassium, magnesium and manganese—was higher under no-till. Regardless of tillage system, increased phosphorus application improved shoot and root growth and uptake of nutrients except zinc, copper and iron.
Appalachian Soil and Water Conservation Research Laboratory, Beaver, WV
Virupax C. Baligar, (304) 252-2808.