The effects of magnesium compounds and of fertilizers on the mineral composition of herbage and on the incidence of hypomagnesaemia in dairy cows

Abstract

1. An experiment, lasting 3 years, was carried out to investigate the control of hypomagnesaemia on a medium-heavy loam soil in Northern Ireland, using as criteria herbage analysis and analysis of blood sera of grazing dairy cows.2. Applications of calcined magnesite and magnesian limestone as soil treatments raised the magnesium contents of herbage slightly but not to levels judged to be safe. Low blood sorum magnesium levels were recorded for cows grazing this herbage although no cases of tetany occurred.3. Magnesium sulphate, appliedas a spray, temporarily raised the ‘apparent’ magnesium content of the herbage but was easily washed off by rain.4. Finely powdered calcined magnesite applied as a dust to the herbage immediately before grazing appeared to be a promising method of control under Northern Ireland conditions.

Comparisons of kieserite and calcined magnesite for sugar beet grown on sandy soils

“…experiment (Allcroft, 1960), 250-500 kg/ha calcined magnesite was found to be enough to prevent hypo-Previous experiments (Tinker, 1967;Draycott & magnesaemia, but in another experiment on a more Durrant, 1969) have shown that spring applica-alkaline soil it gave a much smaller response, tions of kieserite (MgSO 4 .H 2 O) largely prevented McConaghy et al (1963) showed that calcined magnesium-deficiency symptoms and increased magnesite slightly increased magnesium in herbage, sugar-beet yield where the soils contained small but was not sufficient to prevent a deficiency of amounts of exchangeable magnesium. During the magnesium in blood serum of dairy cows.…”

Sources of magnesium for grassland

“…Using commercial magnesite (MgO), Griffiths (1959) found that the Mg concentration of grass increased rapidly with a small increase in yield. Rook & Wood (1960) used 3140 kg/ha of calcined magnesite to double the mean level of Mg in grass, yet McConaghy et al (1963) using the same source found only a slight increase in Mg concentration. When Parr & Allcroft (1957) compared calcined magnesite with magnesian limestone supplying equivalent amounts of Mg, the Mg concentration of pasture was increased by 73 and 23% respectively.…”

“…Similar findings were reported by Reith (1954) after 5 months with no response in yield from magnesian limestone, but over a 3-year period the Mg concentration in mixed herbage was increased by 55% over no lime or CaCO 3 treatments. Using magnesian limestone, Griffiths (1959) found an increase in both yield and Mg concentration, McConaghy et al (1963) found a slight increase in Mg concentration while Wolton (1960) found magnesian limestone to be a poor source of magnesium. In the face of so many conflicting reports we have compared the effects of several magnesium fertilizers on yield and Mg concentration of a mixed sward, and on exchangeable soil magnesium in a field experiment over three seasons.…”

Effect of species, temperature, and nutrition on the cation concentration of cool season grasses with special reference to grass tetany (Hypomagnesaemia)

“…Soils with finer textures, however, required substantially higher amounts of Mg. Todd therefore concluded that fertilization with Mg was economically impractical except on coarse textured soils, soils with a low pH, or soils with low K availability. McConaghy et al (1963) also concluded that fertilization of fine textured soils was ineffective in raising plant tissue concentrations of Mg. In this study he applied calcined magnesite and Mg-limestone.…”