Just taking advantage of timely planting, not necessarily using Group IV's, can contribute to increased yields. Late planting dates are usually the most damaging to yields. Yield losses are variable, but after mid-June, yields decline rapidly. Late-planted soybeans have more limited root systems and cannot withstand long periods of drought. Near-ideal rainfall distribution is needed if late plantings are to succeed.
Late plantings are also more likely to require insect control.
Planting in narrow rows and irrigating can minimize the loss in yield due to late planting. In general, yields will be positively affected by planting earlier than this period vs. the negative effects on yield from planting later. If there is a likelihood you cannot plant the entire crop during the optimum time, it is better to begin planting early rather than risk late planting. Row Spacing Soybean varieties adapted to Mississippi can produce high yields over a range of row spacings and plant populations. Soybeans planted in wide rows can be adequately irrigated and can produce yields equivalent to narrow rows.