Effects of saline-sodic soil chemistry on soybean mineral composition and stomatal resistance

Productivity of soybeans grown on a gradient of soils of increasing saline-sodic character were studied in greenhouse experiments. Soils with electrical conductivity (EC) exceeding 3. 20 dS m** minus **1 would not support soybean growth. Soybean plants accumulated significant quantities of Na when soil solution sodium adsorption ratio (SAR) exceeded 6. 4 and relative tissue Na accumulation was highly correlated with SAR. Estimates of potential productivity were made by stomatal diffusive resistance measurements at three vegetative growth stages. In a second experiment, saline-sodic soil was amended with four rates of gypsum. Plant dry matter production was minimized with the 2. 6 g kg** minus **1 amendment, which also produced plants with significantly reduced and negligible Na contents. The addition of gypsum apparently reduced the detrimental effects of physical impedance to root development and function.