Soil chemistry and nutrient concentrations in perennial ryegrass as influenced by gypsum and carbon amendments

Plant growth is affected by soil properties that can be improved through addition of amendments and other management practices. Use of gypsum as a soil amendment for improving agricultural yields, and soil and water quality is increasing, but knowledge is lacking on how it affects the soil’s chemical properties and plant growth. This greenhouse study measured changes in soil chemistry, growth and nutrient uptake response of ryegrass (Lolium perenne) grown in two contrasting soil types amended with crop residues, glucose, and gypsum. The soil chemical properties, biomass yield, and elemental composition of ryegrass shoots and roots were evaluated. Residue addition significantly increased total soil N and pH, and glucose significantly lowered soil pH. Gypsum significantly increased pH in the 25-40 cm layer only and exchangeable Ca in all layers, and decreased Bray P-1 in the surface layer by 40%. No significant effects were observed in above-ground ryegrass biomass with addition of inputs. Compared to the untreated soil, gypsum increased Ca and S uptake by 50 and 259%, respectively, in the last harvest and Ca, S and Mo in roots by 77, 175, and 18%. Addition of residues and gypsum improved soil chemical properties, nutrient availability, and uptake, but not ryegrass yield.