PHOSPHATIC MANURING.

Otago Witness, Issue 2882, 16 June 1909, Page 6

PHOSPHATIC MANURING.

Although Mr John Hunter, the wellknown agricultural chemist and conductor of the Dalmeny experiments — which will long be remembered as haying afforded demonstration of the superiority of frequent light dressings of lime to ti-eavy applications at long intervals— continues his antagonism to basic slag as a fertiliser, ' recent"* evidence is strongly confirmatory of the value of this article as a phosphatic manure for roots as well as for grass. A mixture of superphosphate and ground lime has been much advocated as a manure for turnips, and has found adherents in New Zealand, sometimes with good comparative results, probably where the soil has been very deficient in lime; but" in England and Scotland, while the superphosphate and lime has given better results than 4 tons of lime pei acre, and superphosphate alone has done still better, basic slag has proved the best of all improvements employed. By the use of basic slag not only is the crop greatly increased in ■weight, but its feeding * value also is enhanced in a marked degree, as has been proved particularly in the Cockle Park experiments originated by Professor SomerviHe. Much of the success of slag i> no doubt due to the fact that not only is its phosphate non-acid, but strictly alkaline, and also to the fact that the slag has about 45 pei cent, of available lime in its composition. These characteristics give to slag a value much greater than is as yet generally recognised, and ■ render it the 'most efficient' phosphate manure for swedes, turnips, mangolds, and potatoes, as well as foi pastures, i Roots with which slag has been applied at sowing are sometimes a little slow of growth in the early stages, but they soon overtake and often pa.°s those which receive different manurial treatment, and often the roots' are smaller, but they weigh heavier in proportion to bulk, and are of more solid and finer texture and eat sweeter, while they are more free from disease and keep sound much longer. Basic slag has lately had a great vogue in New ''Zealand, and has generally figured well in comparative experiments, both with grass and with roots. It has been the most successful manure for worn- , out pastures in the Agricultural Department's experiments as well as on the experimental plots on the Government farms, arM it exercises its qualities over ; a very wide range of soils and climate. The Agricultural Department should soon have available some precise information on the subject of manuring, from the tests made by farmers on their own farms as well as from the longer-con-tinued experimental fai-m tests. The warning seems to be still necessary to j obtain a guarantee when purchasing the slag.