Concentrations of nitrogen, phosphorus, potassium, calcium, magnesium, sulphur and sodium were measured in eight perennial ryegrass cultivars, grown at four sites in New Zealand. The herbage samples were collected from pure ryegrass plots, grown with two nitrogen fertiliser rates with three sites sampled in spring and all four sites in autumn. There were significant differences among the cultivars for all elements except potassium, extending the results of earlier research to commercial cultivars. There were cultivar x season interactions for most of the nutrients with lower concentrations in spring, probably reflecting growth dilution caused by high growth rates. Tetany ratios (potassium/(magnesium + calcium)) were almost all below the critical threshold where stock health is impaired. It is suggested that breeding ryegrass for lower shoot phosphorus concentration should be prioritised because of the economic and environmental benefits to be gained from farming with lower phosphate fertiliser requirements.
Crush, J. R., Lee, J. M., Cosgrove, G. P., Rossi, L., Chapman, D. F., & Stevens, D. R. (2018). Herbage macronutrient concentrations of eight perennial ryegrass (Lolium perenne L.) cultivars grown in four regions in New Zealand. New Zealand Journal of Agricultural Research, 61(2), 285–300. doi:10.1080/00288233.2017.1418397