No abstract

ABSTRACfMagnesium fertilisers and lime had no detectable effects on levels of major elements other than Mg and Ca. Treatments which raised the soil pH slightly depressed herbage Mn levels.Mn and S were always much higher, P, K, and Na usually somewhat higher, Mg, Zn, Cu, and Fe somewhat lower, and Ca, N, and B invariably much lower in grasses than in associated white clover.The pattern of seasonal changes in levels in grasses differed from that in clover, especially in the case of N, P, and Mn. Though mixed herbage N levels were "high" (about 4%) in late winter and early spring, values for grasses indicated that nitrogen deficiency limited growth of grasses growing in association with white clover in spring and summer.

No abstract

Various magnesium fertilisers applied at rates equivalent to 4 cwt Epsom salts per acre on a pasture on Hamilton clay loam. containing 1.3 m.e. % exchangeable Mg, produced only very small increases in mixed herbage magnesium levels, ranging on average from 3% (dolomite and calcined dolomite) to 7% (calcined magnesite) over a period of two-and-a-half years. The increases were of the same order as predicted by the square roots of the ratios of the soil Mg levels. Absolute and relative increases were greater in white clover than in associated grasses. Seasonal variation in magnesium levels was much greater than any changes induced by the fertiliser treatments. Values were at a maximum in summer and a minimum in late winter to early spring. Mg concentrations in grasses were significantly associated with mean daily incident radiation, hours of sunshine, soil temperature, moisture deficit, and to a smaller extent inversely with percent Nand K in the herbage dry matter. Mg levels appeared to be unrelated to rate of growth. At the time of maximum values, magnesium levels in grasses were higher than in white clover, but for most of the year, especially during the critical period for hypomagnesaemic tetany, levels in grasses were lower than in white clover. Calcium changed seasonally in a similar way to magnesium.

View related articles Citing articles: 27 View citing articles Some effects of cattle dung on soil properties, pasture production, and nutrient uptake Il. Influence of dung and fertilisers on sulphate sorption, pH, cation-exchange capacity, and the potassium, magnesium, calcium, and nitrogen economy By C. DURING, W.