Soybean Root Growth in Response to Soil Environmental Conditions

Abstract

Soybean roots anchor the plant, provide sites for nodules containing nitrogen-fixing bacteria, synthesize hormones that regulate growth and development, and absorb water and minerals required by the plant for growth. Diffusion of gases is restricted in waterlogged soils, soybean and most other agricultural crops usually grow better in a free-draining soil than in a completely waterlogged soil environment. Nitrogen fixation by the soybean-rhizobia symbiosis is also influenced by soil temperature. Several workers have investigated the effects of soil compaction on root growth of soybean. In many areas of the world, soybean yields are reduced by calcium deficiency or aluminum toxicity, especially during drought. The calcium concentration required for soybean root elongation is quite low if other cation concentrations also are low and if no toxic ions are present. In the Brazilian Cerrado, soybean yield was reduced when aluminum saturation on the cation exchange complex exceeded 40%.