Management of Corn for Silage Production in South Central USA

Abstract

Relocation of large dairy operations into the south central USA during the mid-1980s created the need for local production of large quantities of high-quality forage. Corn (Zea mays L.) silage was recognized as a forage for meeting this need, but production information was limited. Corn was grown at Stephenville, TX, on Windthorst fine sandy loam (fine, mixed, thermic Udic Paleustalf) soil during 1987, 1988, and 1989 to determine optimum fertilizer N rate and plant density, and to compare dryland production with supplemental irrigation. Dry matter yield, partitioning of dry matter to morphological components (ear, stalk, and leaf), forage quality, stalk diameter, and production economics were studied. Water treatment was either dryland or dryland plus supplemental irrigation. Nitrogen rates were 0, 160, and 320 lb/acre annually. Plant densities were 7 300, 14 500, 29 000, and 58 000 plants/acre. Supplemental irrigation increased dry matter yield in 1987 and 1988, increased digestible dry matter yield all years, reduced leaf percentage in 1987 and 1988, decreased stalk percentage in 1987, and increased ear percentage in 1987. Dry matter yield increased as plant density increased at the 160 and 320 N rates each year and at 0 N in 1989. Digestible dry matter yield increased with increasing plant density. Ear percentage decreased at 160 and 320 lb N/acre as stalk and leaf percentage increased. Stalk diameter increased at 160 lb N/acre each year. Increasing plant density for all N rates and water regimes reduced stalk diameter. Economically, the highest return occurred at 160 lb N/acre and a plant density of 29 000 (dryland corn; $138.56/ acre) to 58 000 (irrigated corn; $154.06/acre) plants/acre. The difference in net return between dryland and irrigated corn at optimum N rate and plant density was $15.50/acre (not accounting for labor and fixed costs). We conclude that dryland corn fertilized with 160 lb N/acre and grown at a plant density of 29 000 plants/acre produced the optimum dry matter yield and profit. Less costly water could improve profitability of supplemental irrigation