THE EFFECT OF DUNG AND URINE AND ITS INTERACTIONS WITH APPLIED NITROGEN, PHOSPHORUS AND POTASSIUM ON THE CHEMICAL COMPOSITION OF PASTURE

Abstract

The importance of the grass/clover balance of a pasture in determining the effects of manurial returns and fertiliser applications on the chemical composition of the sward is shown.The response to applied nitrogen was very dependent on the presence or absence of the animal excrements. For example, the N recovery from an application of 18 cwt. per acre of nitro‐chalk was only 2% in the absence but 68% in the presence of the grazing animal.Urine caused a marked increase in the N and K content and the yield of pasture, particularly when returned in quantity to a high‐producing grass‐dominant sward, and at the same time tended to depress the Ca, P and Mg content. Urine K was superior to fertiliser K, per pound of K returned or applied, in raising the K content of the pasture.By comparison, dung had little direct effect on chemical content; even when returned in large amounts it affected the Ca and K content of the pasture to a relatively small extent. The P returned in the dung had little effect on the P content of the pasture and was inferior to superphosphate in this respect.Together, as in normal grazing, dung and urine tended to counter or enhance their individual effects.There was a positive correlation between the Mg and P content of the pasture and a negative correlation between Mg and K. Brief mention is made of the possible importance of the nutrient balance in pasture as a factor in animal health.