Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 21, 2001
Publication Date: October 21, 2001
Technical Abstract: Dryland soybean [Glycine max (L.) Merr.] production methods on the semiarid southern High Plains, SHP, were adapted from irrigated or rainfed areas. Recommended SHP planting dates vary from late April to June depending on water use strategy, with similar difference in cultivar maturity. The objective was to identify the best planting date, population, and cultivar maturity for dryland soybean production on the SHP using crop growth simulators. Soybean growth and yield were modeled with GLYCIM using Pullman (fine, mixed, superactive, thermic Torrertic Paleustoll) soil properties and long-term (1958-2000) weather records for all combinations of planting date (day 116, 135, 155, 174), population (125,000 to 160,000 plants ha**-1), and cultivar maturity (early to late). Validation of modeled with measured yield was limited by the availability of dryland soybean data; but the overall yield projections were similar to measurements. Under dryland conditions, the simulations indicate that mid-May to early-June planting dates achieved greater yields averaged across maturity categories. Earlier planting consistently produced the lowest and most variable modeled yield. Higher modeled-yield of about 1,200 kg ha**-1for early maturity soybeans was attributed to water use for pod fill instead of vegetative growth.