Soil Analyses after Growth of Six Winter Cover Crops.

Little information exists concerning the appropriate cover crop to grow during the winter in the Great Plains. Therefore, over a three-year period we compared legume and non-legume winter cover crops grown at two locations in Kansas: Manhattan, in the northeastern part of the state, and Hutchinson, in the south-central part of the state. The legume cover crops were alfalfa (Medicago sativa L.), Austrian winter pea (Pisum sativum var. arvense Poir.), and red clover (Trifolium pratense L.). The non-legume cover crops were triticale (X Triticosecale; Triticum X Secale), winter oats (Avena sativa L.), and winter wheat (Triticum aestivum L.). The cover crops were planted and terminated at times corresponding to how they might be used in a corn (Zea mays L.) or forage sorghum [Sorghum bicolor (L.) Moench] rotation. However, the rotations were simulated, and corn and sorghum were not planted. At Manhattan, the soil was a Bismarckgrove-Kimo complex, and, at Hutchinson, the soil was a Funmar-Tarver loam. Previously we reported that because the leguminous cover crops often did not produce stands, non-leguminous winter cover crops should be planted. Here we report the soil analyses for one of the three years (2010-2011). The soil was analyzed for pH, organic matter (OM), total nitrogen (N), and total carbon (C) in the fall before the cover crops were planted and in the spring after the cover crops were harvested at times to simulate the corn and sorghum rotations. Analyses of soil growing the leguminous cover crops were similar to those growing the non-leguminous cover crops. The pH’s of the two soils were similar, but the OM, N, and C were higher in the soil at Hutchinson than in the soil at Manhattan. Analyses of soil in the corn rotation were similar to those in the sorghum rotation. The OM, N, and C in the soil at Hutchinson before planting and after harvest were similar. However, C increased in the soil at Manhattan as a result of planting the cover crops. The average value and standard error of C before planting was 0.43+0.01% C; for cover crop harvest at corn planting time, the average value was 0.48+0.01% C, and, for harvest at sorghum planting time, it was 0.50+0.01% C. The results indicated that cover crops increased C in a soil low in C.