The uptake of magnesium by plants from the use of the magnesium silicates serpentine and dunite was compared with that from dolomite and talc-magnesite, the latter two minerals being commonly used magnesium fertilisers in Nelson.Tobacco plants, white clover, and perennial ryegrass were grown in pots filled with sawdust. Plant nutrients were supplied in solution, except magnesium, which was applied at different rates of ground fertiliser. Field trials with tobacco and pasture are also described.When the four magnesium fertilisers were compared on an equal weight basis, dunite proved to be the most efficient; serpentine was equal to dolomite in certain cases but superior in the pot trials with tobacco and clover. Talc-magnesite gave variable results.Solubility Itests with water and dilute acids showed that the magnesium silicates serpentine and dunite are readily broken down, releasing magnesium.

Calcium nitrate and calcium chloride tree sprays at different concentrations are compared. Calcium chloride, with about twice the calcium content of the nitrate, gave as good-control of bitter pit at half the concentration of the nitrate, which relates the effectiveness of these materials to their calcium content. Colour development on apples was better with calcium chloride than with the nitrate. The slow movement of calcium through apple flesh is demonstrated. When inadequate calcium sprays are used, -bitter pit may develop internally without showing its-presence on the apple surface.

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On a newly sown pasture suitably treated with superphosphate four replications of applications of ground limestone at 0, 1, 5, 10, 20, and 40 cwt were set out; across these limed strips sodium molybdate at 0, 1, 2 and 4 oz per acre was applied, giving 24 treatments per replication. At low rates of liming, sodium molybdate increased clover growth more than at high rates; there was no advantage in applying more than 2 oz sodium m::.lybdate per acre. Increasing the rate of application of limestone improved the growth of the pasture even in absence of molybdate. Three ye:us after laying down, all plots carried the same amount of fodder in the spring. Implic3.tions of this result are discussed. Nitrogen, phosphorus, and calcium contents of white-clover leaflets varied relatively little with treatment. Manganese content was reduced by liming, but was little al~ered by variation in rate of application of molybdate. Mangal!ese decreased as molybdenum content increased. A logarithmic relationship between manganese content and rate of use of limestone was found. Molybdenum content was increased by successively larger applic::ttions of ground limestone in the absence of molybdate treatment, and by use of sodium molybdate. Logarithmic relationships between molybdenum content of white-clover leaflets and rate of application of sodium molybdate and also rate of use of limestone were found. pH value and exchangeable calcium of the soil were increased by use of limestone, but citric-soluble phosphorus and potassium and exchangeable potassium and magnesium were reduced by such treatment. These results are important in relation to interpretation of analytical data in advisory work.

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