Abstract
The variation in the Na, K, Ca, Mg, Mn, Zn, Fe, P, and N content of herbage in a perennial ryegrass (Lolium perenne) pasture in spring has been measured. For 3-week-old regrowth herbage, the range of N, Mg, Fe, and Na contents III one sampling differed markedly from those in a similar sampling collected along the same transect a few weeks later; in contrast the range of P, Ca, K, Mn, and Zn contents did not differ. Urine produced an increase in herbage N (P<0.01) and K (P<0.001) content but a decrease in Mg (P<0.05), Mn (P<0.01), and P (P<0.001) content. The Ca, Na, Zn, and Fe contents were not significantly affected. The factors responsible for the changes in herbage elemental composition and the potential role of urine-patch herbage in the hypomagnesaemic and hypocalcaemic syndromes are discussed.