The effect of ammonium sulphate treated with a nitrification inhibitor, and calcium nitrate, on growth and N-uptake of spring wheat, ryegrass and kale

Abstract

SUMMARYWheat, ryegrass and kale were grown with ammonium sulphate (treated with a nitrification inhibitor) or calcium nitrate supplying 50 and 100 lb N/acre, and without fertilizer-N. Plants were sampled at various stages, dry weights measured, percentage N determined and N uptakes calculated.Initially wheat and ryegrass grew better and took up more N with ammonium fertilizer than with nitrate. Final yields of dry matter did not differ between forms. Kale produced more dry matter with calcium nitrate than with ammonium sulphate. All crops produced more dry matter with fertilizer-N than without. Fertilized crops contained greatest weights of N 109 days after sowing, when wheat and ryegrass had more with ammonium than with nitrate and kale had less. The 50 lb N/acre as calcium nitrate produced the most wheat grain/lb of fertilizer-N.During the period when growth and N uptake were fastest, wheat grew faster with ammonium than with nitrate, ryegrass grew similarly with both forms, and kale faster with nitrate; wheat and ryegrass took up N faster from ammonium sulphate and kale from calcium nitrate.Mature wheat recovered 58% of the fertilizer-N from calcium nitrate and 43% from ammonium sulphate. After 21 weeks of growth, kale recovered more N from calcium nitrate (50%) than from ammonium sulphate (24%), whereas grass recovered about 40% from each.