1988/03/01 by L. G. Heatherly, Larry G. Heatherly · 3 citations
Agricultural and Biological Sciences · #Soybean genetics and cultivation #Legume Nitrogen Fixing Symbiosis #Agronomic Practices and Intercropping Systems
paper · doi:10.2134/agronj1988.00021962008000020017x
Abstract Because of adverse weather and management decisions, soybean [ Glycine max (L.) Merr.] is often planted beyond the period considered optimum. In the southern Mississippi River alluvial plain, this frequently occurs on clay soil. Research was conducted from 1984 through 1986 at Stoneville, MS, on Sharkey clay (very‐fine, montmorillonitic, nonacid, thermic Vertic Haplaquept) to determine the effect of irrigation and row spacing on seed yield and yield components of early or mid‐May versus late‐June plantings of soybean. ‘Braxton’ was planted in 0.53‐ and 1.02‐m‐wide rows and was either nonirrigated or irrigated from the R1 to R6 stages. Irrigation significantly increased yield regardless of row spacing or planting date, but the increase was always greater for early plantings. Seed yields from the irrigated early plantings in 1984,1985, and 1986 averaged 3570, 2960, and 2695 kg ha −1 , while the later plantings averaged 3115,1900, and 1425 kg ha −1 , respectively. Without irrigation, yield differences between planting dates were not significant. Average nonirrigated yields were 1495,1760, and 185 kg ha −1 for 1984,1985, and 1986, respectively. Narrow rows produced 100 kg ha −1 more seed when averaged over all environments, and row spacing did not significantly alter the planting date × irrigation treatment interaction. Yield increases from irrigation were primarily attributable to increased number of seed. These results show that (i) late planting of soybean on clay soil in either row spacing used will result in significant yield decline even with irrigation, (ii) nonirrigated production of soybean on clay soil is risky, and (iii) choice of row spacing is not as important a consideration as is the alleviation of drought stress on this soil type regardless of planting date.