Magnesium, Potassium, Sodtum and Calcium Contents of Herbage as Influenced by Fertilizer Treatments Over a Three‐year Period

Abstract

Results are given showing the effects of applying nitrogen, phosphorus, potassium, sodium and magnesium on the yield and mitieral composition of herbage cut repeatedly at the silage stage over a 3-year period. Grasses and clovers were separated before analysis. A combination of nitrogen and potassium was essential for the maintenance of high yields. Superphosphate did not increase drymatter yields. 4 cwt. of common salt was ineffective, even under conditions of acute potassium deficiency; it reduced responses to potash and decreased yields when given with potash.Ammonium sulphate and common salt greatly increased sodium uptakes and muriate of potash depressed them. Potassium contents were greatly reduced by repeated nitrogen applications and muriate of potash gave consistent and significant increases. Potassium-deficient grasses contained more sodium than potassium.Ammonium sulphate increased magnesium contents and muriate of potash reduced them. There was a marked tendency for both effects to be more significant in late-season cuts. In late May the effects were small. 22 and 44 Ib. Mg/acre as magnesium sulphate had variable effects on herbage magnesium. These changes are discussed in relation to hypomagnesaemia.None of tbe fertilizer treatments altered the calcium contents of either grass or elover.

Nitrogen Fertilization of Reed Canarygrass and Its Effects on Production and Mineral Element Content

“…Working with a prcdominantly perennial ryegrass sward, Stewart and Holmes (1953) found N increased levels of Ca and Mg, but decreased K. Of the trace elements, only Cu showed any marked response to N, the level increasing. In herbage from a mixed grass sward Hemingway (1961) found a similar effect on K and Mg, but not on Ca. Rahman et al (1960) reported K contents were increased by N.…”

The Effect of Various Manuring Practices on the Magnesium Status of Spring Herbage

“…Although a recommendation to use potassic fertilizers in the autumn instead of in the spring preceding grazing is common (1), there is no published experimental evidence to support it (6). The present report concerns the investigation of the effects of variations of rate and times of application of muriate of potash on the magnesium status of spring herbage.…”

Seasonal variations in chemical composition of pasture

“…Red clover gave the highest Mg values. Hemingway (1961) found increases in Ca and Mg in grass, cut repeatedly at the silage stage, over the season, but no increases of these elements in clover. Results for K and Na were more variable, although Na tended to increase with season in both grass and clover.…”

“…Under such conditions, the concentrations of nutritionally important elements may be important in relation to reproductive performance Or to the incidence of metabolic disease (for example, Walker et al 1953;Johns 1955;Hemingway 1961;Jones 1963;Metson et al 1966;Butler & Metson 1967;Wilson & McCarrick 1967;Reid et al 1970).…”