Comparative phosphorus requirements of five annual medics

Abstract

The dry herbage yield response of dense swards of five annual medics (Medicago truncatula cv. Paraggio, M. murex cv. Zodiac, and M. polymorpha cw. Serena, Santiago, and Circle Valley) to applications of nine levels of phosphorus (P) (from 0 to 320 kg P/ha as single superphosphate) was measured in a field experiment on alkaline soil (pH 7.2 in water and 6.4 in 0.01M calcium chloride). The comparative P requirements of the medics was calculated from the amount of P required to produce 90% of the maximum yield. Applying different amounts of P to the medics did not affect either seedling establishment or maturity (as measured by the interval between emergence of seedlings to the appearance of first flowers). The order of the P requirement of the medics varied for different harvests, but generally M. polymorpha cv. Serena and M. truncatula cv. Paraggio required the least P to produce 90% of the maximum yield and M. murex cv Zodiac required the most P.

Notes

Present address: Agriculture Western Australia, P.O. Box 1231, Bunbury, Western Australia 6231, Australia.