ROTATIONAL GRAZING

Sun (Auckland), Volume IV, Issue 1058, 23 August 1930, Page 27

ROTATIONAL GRAZING

EXPERIMENTS WITH MANURES Press Association NELSON, Thursday. Important results obtained in experiments at the Cawthron Institute in connection with the manuring of pastures under the rotational system of grazing were announced today by Mr T. Rigg, assistant-director and chief agriculturist to the institute. Mr. Rigg said a complete manure consisting of superphosphate, sulphate of potash and sulphate of ammonia had given the best results in maintaining both yield and quality of pasture. In the absence of potassic manures ammonium sulphate had detrimentally affected pastures, the percentage of clovers being notably reduced. Suitable temperature and moisture conditions influenced greatly the rapidity and magnitude of the effect of ammonium sulphate. Applications made early in August last year gave an Increased production of nearly 100 per cent, during that month. During September its effect on the yield was more marked, a daily production of nearly 221 b of dry matter an acre being obtained against on untreated pastures. Taking the figure of 22Jib of dry matter to be the production requirement of an average dairy cow in milk, it would appear that the application of Icwt of ammonium sulphate an acre ■would provide an increased stocking of approximately one-third of a cow an acre for a period of at least six weeks. The chemical data showed very definitely that both season and manuriaJ treatment have a pronounced effect on the chemical composition of pastures. Phosphates, potash and nitrogen had been readily taken up l>y pasture plants, so that the quantities of these constituents were notably increased. Lime treatment of land had always given a higher percentage of desirable constituents in pasture grass under manurial treatment than had been the case on unlimed ground. On a number of pastures it had been found that the chemical composition was most suitable for growing or lactating animals in mid-spring and autumn. In the early spring the amounts of certain minerals had been found to be somewhat low. At the end of December, particularly during dry periods, the chemical composition of pastures tended to be poor. In certain poor pastures the amount of phosphate and protein had decreased almost 50 per cent. Experience had shown that stock on certain mineral deficient pastures suffered most from stock ailments at this time.