Optimizing crop geometry for enhanced growth and yield of soybean [Glycine max L. (Merrill)] maturity groups in western Ethiopia

Increasing soybean [Glycine max L. (Merrill)] productivity relies heavily on optimizing crop geometry, encompassing both inter- and intra-row spacing. This crucial agronomic practice directly impacts the productivity of soybean crops, making it vital for farmers to consider soybean maturity group when determining optimal crop geometry. Hence, the study was conducted to determine the effect of inter- and intra-row spacing on yield and yield components of soybean varieties and to determine appropriate plant spacing for each maturity group of soybean varieties to achieve a high yield of soybean in the study area. Two soybean varieties from each maturity group, four inter-row spacing (30, 40, 50, and 60 cm), and two intra-row spacing (5 and 10 cm) were arranged in factorial combinations in randomized complete block design with three replications. The results showed that days to flowering, days to maturity, plant height, number of seeds/pod, number of pods/plant, and 100-seed weight were significantly influenced by the main effect of varieties, inter- and intra-row spacing for each maturity group of soybean varieties. The highest grain yield was recorded from narrow inter-row spacing for early and medium maturity groups regardless of intra-row spacing while the highest grain yield was obtained from 50-cm inter-row spacing for late maturing groups. Thus, it can be concluded that 40-cm inter-row spacing is recommended for early and medium soybean varieties, while 50-cm inter-row spacing is recommended for late-maturing soybean varieties for western parts of Oromia and similar agroecologies.