BROWNTOP AND PASTURE NUTRITION

Abstract

Pot experiments have shown that browntop is more efficient in utilizing scarce phosphate than is white clover when white clover is obtaining nitrogen either from fixation or from the soil. There is evidence that browntop can reduce the amount of phosphate available to clover both by direct competition and by decreasing the soil moisture and hence ,the availability of phosphate. These effects are probably not peculiar to (browntop which, however, does have a mat that can effectively shade clover stolons thereby reducing #the activity of clover stolon nodes and the ability of clover to regrow leaf. Reduced phosphate availability and stolon shading exert a powerful control on clover growth and this control is likely to be strongly expressed on set-stocked hill country, particularly if the soil has a high P fixing capacity and easily dries out.