Performance of Selected Silage and Summer Annual Grass Crops as Affected by Soil Type, Planting Date, and Moisture Regime 1

In order to better understand the relative performance of forages grown on soils of different characteristics, field experiments were conducted over a period of 5 years on two soils at each of six locations to determine the effects of soil mapping unit and climatic differences on the silage yield and grain content of corn ( Zea mays L.) and grain and forage sorghums ( Sorghum bicolor (L.) Moench) and on the forage production of a sorghum‐sudangrass hybrid ( S. bicolor ) and of pearmillet ( Pennisetum americanum (L.) K. Schum). The soils at each location were selected for their differences in moisture supplying capacity. Climatic differences were obtained by location effects, planting dates, and irrigation. The 82 location‐treatment‐year conditions studied pointed to the dependence of yields of corn, grain and forage sorghums, and pearlmillet on soil and climatic environments. Higher yields resulted from the soil with the more desirable moistureholding characteristics in the “pair” at each location. Total silage stage dry matter production and grain content were usually higher from early plantings than from those made 5 to 6 weeks later; conversely, delay in planting resulted in relatively more green‐chop sorghum and pearlmillet dry matter production after August 1 than early plantings. Irrigation generally resulted in higher corn, grain and forage sorghum silage yields than natural rainfall alone, but it did not affect substantially production of green‐chopped sorghum and pearlmillet, illustrating the greater tolerance of these two crops to moisture stress. These results clearly indicate the interdependence of forage production with land selection.