Research Note:The influence of applied nitrogen on the root development of Lolium perenne L. one year after establishment

Abstract

The effect of different levels of applied nitrogen (N) (ranging from 120-720kg N ha^-1 a^-1) on the root development of perennial ryegrass (Lolium perenne L.) was examined at the end of the establishment year. Increasing levels of applied N increased perennial ryegrass root organic matter (OM) content in the top 50mm of the soil, while a corresponding decrease in root OM content was observed in the 100-200mm soil depth category. Increasing levels of applied N did not have a significant effect on root OM content in the 50-100mm or the overall 0-200mm soil depth category. Lower levels of applied N (120-360kg N ha^-1 a^-1) may be more conducive to promoting deeper root development than higher levels of applied N (480-720kg N ha^-1 a^-1), but this would require an investigation beyond one year. Perennial ryegrass is extremely shallow-rooted, with approximately 75%of the root mass occurring in the top 50mm of the soil. This stresses the need to pay careful attention to irrigation scheduling.

African Journal of Range & Forage Science, 12(3): pp. 131-132