Improving emergence of soybean ( Glycine max ) with straw mulch and other practices under normal and crusted soil conditions

Poor emergence is a major problem in soybean [ Glycine max (L.) Merrill]. A high emergence count leading to an optimum plant stand is a pre-requisite to obtain high grain yields. The results of three experiments on emergence in soybean are reported in this paper. Two field experiments were conducted to study the influence of wheat straw mulch, farmyard manure (FYM) mulch and seed soaking in water on the emergence of soybean under normal conditions. Immediately after sowing, covering rows of soybean with 3 t wheat straw ha −1 (row mulch) or the whole plot with 6 t wheat straw ha −1 (plot mulch) showed a profound effect on improving both the speed of emergence and the final emergence count. Row mulch with 5 t FYM ha −1 only improved emergence in one year and its effect was not as great as with straw mulch. Soaking the seeds in water (on-farm seed priming) for 4, 8 or 16 h reduced emergence drastically. Another field experiment was conducted to study the effect of different mulching treatments or crust breaking in alleviating the crust effect of simulated rain on the emergence of soybean. Covering the soybean rows with 3 t wheat straw ha −1 (row mulch) either before or after simulated rain improved the emergence count. Covering the soybean rows with 5 t FYM ha −1 or breaking the crust also improved emergence, though the effects were not as good as with wheat straw mulch. The results suggest that the use of wheat straw mulch or FYM mulch can improve emergence in soybean in both normal and crusted soils, possibly by lowering the maximum soil temperature and conserving soil moisture.