The comparative response of tropical and temperate grasses to varying levels of nitrogen and phosphorus nutrition

Abstract

Ten temperate and nine tropical grasses were compared in glasshouse trials in their response to a wide range of nitrogen and phosphorus nutrition. For all attributes there was a gradation in species response within the temperate and tropical groups; the means for the two groups were different although the spread of values showed some degree of overlap between the groups. In general, the temperate grasses had more tillers per plant and a lower top/root ratio than the tropical grasses. The tropical grasses grew better than the temperate grasses at low nutrient combinations but the reverse was true for the high nutrient combinations. The linear response to nitrogen of the tropical group of species was lower than that of the temperate group but was probably a consequence of the ability of the tropical grasses to grow at low nitrogen levels since the curvature in nitrogen response was similar for all species. Within both groups of grasses, the proportional response to nitrogen increased with increase in the species potential for yield. The temperate grasses accumulated nitrogen and phosphorus to higher concentrations in the plant tops, and were higher in digestibility, than the tropical grasses. Nevertheless, the tropical grasses would appear to have the potential for higher quality forage than is generally produced in field situations.