Effects of cow urine and its major constituents on pasture properties

The effects of cow urine and equivalent nitrogen, potassium, and sulphur treatments on pasture yield, botanical composition, herbage chemical composition, and N fixation by clovers ~ere examm~d during winter and spring. Urine caused a large increase in ryegrass Yield, due entirely to its N component. The effect on yield lasted 2‐3 harvests and was followed by a decrease in clover growth. The sulphur treatment (sodium sulphate) reduced the depresslve effect ofN on clover growth. Urine increased the N concentratiop of grass (particularly the nitrate fraction) and increased the potassium concentration of grass and clover. N fixation by clover was markedly decreased by urine, particularly during the winter. The treatments were replicated at either end of a paddock to. examine the influence of the previous grazing method (nine years of break‐feeding in the, same dlrection, wlth no back‐fencing) on fertility transfer. At the low fertillty end, lower levels of pasture production and soil nutrients were measured and pasture response to urea was higher.