Plant and row spacing effects on soil water and yield of rainfed summer soybean in the northern China

Abstract

Productivity and water resource-use efficiency are crucial issues in sustainable agriculture, especially in high-demand water resource crops such as soybean [Glycine max (L.) Merr.]. The aims of this research were to compare planting pattern in soybean, evaluating soil moisture content (SMC), yield and water use efficiency (WUE). A 2-year field experiment (2006–2007) was carried out in the north of China. The summer soybean (cv. Ludou 4) experiment consisted of 5 planting patterns under the same plant population density (3.09 × 105 plant/ha), and row spacing (cm) × plant spacing (cm) was 18 × 18 cm (A), 27 × 12 cm (B), 36 × 9 cm (C), 45 × 7.2 cm (D), 54 × 6 cm (E). The results showed that SMC and soil storage water (SSW) decreased with evapotranspiration (ETa) increments after reproductive growth stage, and there were remarkable differences between treatments with decreasing rainfall. SMC curve characteristics in the 0–0 cm soil profile were related to rain; the scope changes of shallow SMC were higher than those of deep SMC. The study revealed that yield and WUE had a negative correlation with row spacing, and they were statistically greater in narrow rows, which approximated equidistant plant spacings, compared to wider rows (P < 0.05). The study also indicates that enhanced productivity and WUE of rainfed summer soybean can be achieved via row spacing reduction and plant spacing widening under uniform planting density.