The transference of nitrogen from pasture legumes to an associated grass under several systems of management in pot culture

Abstract

The extent of underground transference of nitrogen from three pasture legumes, each growing in association with a grass, has been studied in pot culture under several systems of management during the first 12–18 months after sowing.

The three legumes performed quite differently. Subterranean clover did not release any nitrogen until senescence and then produced a rapid transference. White clover was competitive for nitrogen until the autumn-winter period. Lucerne released nitrogen gradually over the whole experimental period.

Frequent defoliation of the legumes reduced competition for nitrogen by white clover but also reduced transference from the other legumes. Killing the perennial legumes produced only a small temporary increase in transference.

Wilting and temporary drying treatments also reduced the transference. Thus there was no evidence that the nitrogen transference from lucerne was due to a shedding or decay of nodules induced by defoliation; it could equally well be due to direct excretion of nitrogen from the intact root system.

The significance of the results in pasture establishment in infertile areas is discussed.