Yield and Risk Utilizing Short-Season Soybean Production in the Mid-Southern USA
Maturity Group (MG) V and VI soybean [Glycine max (L.) Merr.] grown in the mid-southern USA often produce low yield. The objective of this study was to determine if yields could be increased and risk of production reduced by utilizing early-maturing cultivars at early planting dates (short-season system). Field experiments were conducted from 1992 through 1994 on Sharkey clay (very-fine, montmorillonitic, non-acid, thermic Vertic Haplaquept) to evaluate mid- April through early-June planting dates (PD), row spacings of 75 and 100 cm, and irrigated vs non-irrigated treatments for selected MG III, IV, V, and VI cultivars. The cultivars were MG III, ‘Williams (W) 82’; MG IV, ‘Asgrow (A) 4715’, ‘Northrup King Ringaround (RA) 452’, and ‘Riverside (RVS) 499’; MG V, ‘Deltapine (DP) 105’ and MG VI, ‘Davis’. Maturity Group and PD had large effects on soybean growth and yield, whereas row spacing and irrigation had small effects and were not important factors in yield determination at most PD. The optimal PD for MG III through V cultivars centered around early May. Yields of MG IV at early- to mid-May PD were equal to or greater than their yields at April PD. In April plantings, MG IV, RA 452, and RVS 499, usually yielded higher than MG V and sometimes yielded higher than MG VI. Adaptation to early PD was related to length of growing season and plant size. Attaining harvest maturity in fewer than 120 d at an April PD or fewer than 108 d at a May PD reduced both plant height and yield. The risk for short-season production was less than for plantings of MG V or VI cultivars because the short-season system produced higher yields and there was no difference between the two systems in yield variation across years.
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