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.

Total annual and seasonal DM production of improved and unimproved resident pastures at three farms in Canterbury

“…Thus, hill country swards become grass dominant unless strict grazing management protocols, aimed at increasing the legume content, are observed (Grigg et al 2008;Olykan et al 2019a). The dominance of browntop (Agrostis capillaris) in many hill country regions suggests grazing has resulted in plants that are short of carbon , and its ability to compete for phosphorous (Jackman and Mouat 1973) further compromises legume survival. Resident pasture is often dominated by such low quality species, that produce a flush of spring production that does not meet the needs of lactating animals, and may take the summer and autumn to be brought under control (Chapman et al, 2021).…”

Persistence: the key to legume performance in summer-dry hill country

“…While nitrogen is often the most limiting nutrient for pasture growth in hill country (Chapman & Macfarlane 1985), phosphorus is the major nutrient constraint for legumes (Edmeades et al 1984). White clover has been shown to be at a competitive disadvantage to browntop in accessing soil P and moisture (Jackman & Mouat 1974), a factor contributing to clover suppression in mixed swards (Harris 1974). Trace elements such as molybdenum can also be limiting for clover production (Jaiyou et al 1993).…”