MANURING THE WHEAT CROP.

Otago Witness, Issue 3031, 17 April 1912, Page 14

MANURING THE WHEAT CROP.

When wheat is .sown after the root crop it should not be necessary to use any manure whatever, particularly if farmyard manure had been used liberally with the previous crop, and the ground had been well worked. But the wheat crop delights in a firm bottom, and steps should be taken in cultivating green crop ground to give it that either by ploughing a very light furrow if the ground is clean, of by consolidating the ground before sowing. If in the spring the plant is tillering out badly in good green crop ground, or if a severe wire worm attack has been experienced, then one hundredweight of nitrate of soda per acre may be profitably applied. But. this should only be necessary to controvert the disastrous effect of a bad season, or some well-de-fined cause of that sort. With a second crop on succession on the same land, the positon is a different one altogether, and an application of two hundredweight of superphosphate per acre might be well repaid. If the land is light the crop will also require the addition of potash, and even then need stimulating in the spring with nitrogenous manure to produce a full second crop. The question would then resolve itself into whether or not it will pay to grow wheat on light land. In his work on " The Feeding of Crops and btock," Mr A. D. Hall says that " wherever the land is not naturally rich, and the markets are such that the farmer cannot obtain a large return per acre, he must cut his expenditure down to low limits, and only indulge in purchased fertilisers to a very limited extent. He must follow a conservative system of farming, being content with low yields, the material for which has in the main been derived from the soil. For every farm there is a sort of level of expenditure on materials like fertilisers, and the more profitable and the richer the land and the more valuable the crops that can he sold the higher will this level become. Bearing this fact in mind, we find that in Britain the wheat crop rarely receives any fertiliser, except, perhaps, a small top-dressing of nitrate of soda or soot in the early spring." The three factors that mainly contribute to the success of the wheat crop are good tillage (which is the most important), pure seedd, and a proper system of manuring when required. One of the principal German papers points out that the chief requirements of all cereal crops is nitrogen and nitrate of soda. Applied in the spring is the best form, and then it does most excellent work ; but it should not be applied late in the season, as it would impede the ripening of the grain. On light, warm soils sulphate of ammonia should he substituted for nitrate, as it is not so liable to be washed out, and its action is more continuous. As regards phosphatic manures, the Germans use super and slag extensively, the former on heavy soils and the latter on soils rich in humus. Dr Dyer, in his book, "Fertilisers and Feeding Stuffs," suggests that a heavy crop of clover is not only good in itself, but is the best preparation for a crop of wheat. By heavily manuring the clover we do double g<xjd,

and if the soil is a fair " -wheat " soil, no autumn-dressing need generally be given. The spring is the critical time for feeding the wheat crop, and the best ai-ent is nitrate of soda. In rainy districts and on loose, open soils it is wise to divide the nitrate into two dressings. When a second crop is taken the autumn phosphatic dressing should certainly not be omitted. M. Donon, French Professor of Agriculture, strongly recommends the application of superphosphate and potash in the autumn. As these artificials "furnish to the roots the assimilable food which is required to assure the normal development of the whole plant," In about two months' time, he says, "after vegetation has started in the spring, the wheat plant which occupies the ground nine months has absorbed 69 per cent, of its requirements of nitrogen and phosphoric acid, 81 per cent, of its lime, and 94 per cent of its potash. At this, early period of its development the plant has absorbed all the potash required while it continues, although more slowly, to draw up the nitrogen and phosphoric acid for its nutrition." A. B. Griffiths says: "Let the farmer bear in mind (1) that wheat and oats require more nitrogen than rye and _ barley; (2) that a dry, light soil requires more nitrogen and'potash than a damp, heavv one ; (3) that organic soils, or those rich in humus, require more phosphoric acid and less nitrogen than soils poor in organic matter; (4) that if the previous crop was a nitrogen-gatherer (clover, tares, lucerne, beans, peas, and leguminous crops generally), a less quantity of nitrogen is required for the next crop ; (5) that if the previous crop was a nitrogen-consumer (cereals, potatoes, beetroots, etc.), a maximum quantity of'nitrogen is essential to keep the land in a fertile condition; (6) that soil rich in lime requires more superphosphate than one jwor in lime." These are the opinions of some of the best authorities we have. The New Zealand wheat-grower on the heavy river flats does not have at present to trouble his head much about the use of fertilisers, but in some places he ought to: it would pay him to do so. At present he trusts to the rich productive power of his land to nourish the wheat plant, his main anxiety being for favourable seasons and good prices. But there is already much wheat land not yielding the crop 3 periodically reaped formerly from them, and it is just as well that'the principles underlying the fertilisation of this crop should be understood.