PASTURE FERTILIZERS

Wanganui Chronicle, Volume 71, Issue 237, 6 October 1928, Page 26 (Supplement)

PASTURE FERTILIZERS

Lecture to Brunswick Farmers by Mr. L. J. Wild

Valuable information on the subject of topdrecsing of pastures was given farmers at Brunswick recently, by Mr L. J. Wild, director of the Feilding Agricultural College. The meeting was convened by the Brunswick branch of the Farmers’ Union, and was presided over by the diairman, Mr T. Currie.

At the outset Mr Wild said that in the supply of fertilisers for plant food three main constituents were considered—nitrogen, potash and phosphate. In New Zealand phosphatic manures were in greatest demand, although in Britain, fertilisers containing nitrogen were used extensively in the late winter or early spring when the process of making nitrates was going on rather slowly on account of the cold weather. As far as potash was concerned, it might be said generally that these manures did not pay in New Zealand. However, he thought that in parts of this district the time was arriving when some potash would pay. Potash was in some favour in the Taihape- district, but after a personal inspection he was rather sceptical as to the results. Nauru Phosphate. Dealing with Nauru phosphate, Mr Wild pointed out that this product was insoluble in water. That did not mean that it was useless in the soil because the water in the soil had acid properties which enabled the fertiliser to be made available as plant food. It became available fairly slowly. Another way of dealing with Nauru phosphate was to turn it into superphosphate by treating it with its own weight of sulphuric acid. Superphosphate did dissolve in pure water and that was why it became available quickly when applied to the land. Under certain conditions in New Zealand superphosphate did not become available, but this was no because it was being washed out of the soil.

The speaker referred to experiments carried out at Feilding on mangold plots. Applications of Nauru and superphosphate to respective mangold plots brought increased yields, but the application of a mixture of both brought the best results. That brought to mind a theory he

'hnd formed as the result of analytical work he had carried out in Canterbury. In New Zealand where most of the soils were deficient in lime, there was a danger of superphosphate combining in the soil with something else and so becoming not available as plant food. In a district where soil was derived from shell rock there was no doubt that there would be a sufficiency of lime, and in such an area superphosphate would give the best results. That would probably apply to the Wanganui district. Fashion In Fertilisers. Basic slag had had a wonderful vogue iu New Zealand, and in some districts it was getting a great run this season. However, he was afraid that as far as this fertiliser was concerned there was a bit of the “fashion” touch about it. It did not compare well as regards price, with the other materials available. It was a waste product from the manufacture of steel and used to be dumped into the North Sea in large quantities until its value as a fertiliser was discovered. The question arose, i which is the best?’’ It was something like the battle of the breeds, and usually the rnan who laid down one particular kind was speaking from a limited knowledge of the subject. “If Nauru can be said to be as good as slag, then it is better than slag,” said Mr Wild. Nauru was 80 per cent, phosphate, and the slag sent to this country was about 17 per cent phosphoric acid. . The latter figure multiplied by 21-5 gave the corresponding value which was 40 per cent, as against 80 per cent, phosphate. If soil was deficient in lime, and the farmer had taken the precaution to apply limo, probably there could be nothing better than super. However, the only place the speaker knew of where liming was done thoroughly (2 tons to the acre) was in Otago and Southland.