SOIL FERTILITY MAY BE INCREASED BY DAIRY FARMING

Bay of Plenty Beacon, Volume 14, Issue 61, 9 November 1949, Page 5

SOIL FERTILITY MAY BE INCREASED BY DAIRY FARMING

(By W. H. Manaeno, Consulting Officer, N.Z. Dairy Board) The harvesting season emphasises the problems of fertility maintenance which is basic to highly productive and profitable farming. Generally speaking dairy farming may be regarded as a method of increasing fertility of the soil. This depends on careful management and maintenance of the cycle, wherein the organic and mineral products of the soil are used and returned to the soil.

Fertility is dependant on many factors. Rainfall, temperature, and topography cannot be greatly altered by farmers, but most other factors may be adjusted by a good farmer. Exc ?ss moisture may be dealt with by drainage, light soils respond to consolidation and such physical difficulties are easily dealt with. On many of our New Zealand soils there are chemical deficiencies—in fact very few areas in the country are capable of high yields without the addition of a mineral which may be deficient. Stock Lick Controversy

The recent controversy regarding the use of complicated and expensive stock licks should have warned farmers of the waste involved in unnecessary purchase of such minerals as are not necessary in most areas. The various research departments in the/ country are working, for the benefit of the country as a' whole and have considerable financial support from the taxpayers. They are therefore able to give advice to v farmers as a result of extensive research by men accepted throughout the world for their proven ability and academic qualifications. Even so, there are problems yet unsolved and qualified men are the first to admit such limitations, whilst others may mix scientific “truth, half truth, and untruth,” to justify expensive experiments by the farmer himself.

The Fields Instructors of the De* partment of Agriculture are appointed to advise on the mineral requirements of soils in their areas so that farmers when considering the limiting factors to fertilityshould make use of such a service—even though the demand overtaxes the ability of an officer to visit all farms. After successful establishment of pasture it is important to maintain’ high production. It is becoming more and more evident from work done at the Grasslands Research Station at Palmerston North that continued high yield from a pasture depends on the farmer’s management of his stock. It is important to realise the draw off of minerals on the dairy farm which are practically the same on milk or cream supplying farms when it is considered that the value of the skim milk is usually concentrated in the piggery. In pounds per annum of common fertiliser the output per acre of the important minerals where a farm is producing at about 1501bs butterfat per acre is as follows: Ground limestone 161bs, 30 per cent potash salts (except for leaching etc.) from a yearly turnover represented by .a pasture producing 9,000 pounds of dry matter per acre per year. The loss is small in comparison with the manurial value of the yearly grass crop which is expressed in hundred weights as follows: Ground limestone I.scwt., Potash Salts Ilcwt., Super 4cwt., Sulph. Amm. 18cwt. Manure Need Decreases It can readily be seen that the maintenance of the full cycle to ensure the full return of this rich manurial shower has high priority on the farm. Once land has be<m raised to high fertility the need for continued heavy dressings of manure decreases. On farms that had reached such fertility levels before the war the manure rationing did not have such serious effect as on farms in the process of fertility building. , High pressure selling and unskilled use of nitrogenous manures near-, ly 20 years ago has put New Zealand off their use as much as the realisation of the role played by clover root bacteria in free provision of this essential plant food. It nevertheless remains the key to successful farming. Unless nitrogen is present for the initial establishment of grasses it is probable that phosphatic dressings are of little value unless the later developing clovers are able to supply some nitrogen stimulation. The “No. 1” white clover developed by Grasslands Research gives the most active bacterial fixation of nitrogen and the value of clover is twofold. First the total yield of a pasture is greatly increased by the clover growth and also higher yields from the grasses are obtained due to the fact that better grasses can grow in association with clover than without it. Secondly the protein content of the sward is much higher

making the feed of far greater value for milk production. It was found that in comparing a pure grass with a clover and grass sward nitrogen as expressed in pounds of sulphate of ammonia was obtained in three ways:— Animal Manure Value That available to the grass from the soil apart from the clover—l7o lbs; that transferred from the clover root bacteria to the grass—4oolbs that yielded in the body of the clov 7 er itself—l,4oolbs. This shows up the very important point that the grazing animal is essential to take the fertility fixed in the clover plant and make it available to the grasses in the manurial shower. This animal topdressing is responsible for one quarter of pasture yield on high producing pasture, but it doubles production on a poor grass sward. This should be sufficient indication of the necessity to feed out hay and silage where it is cut unless the fertility of the paddock is very high when its manurial value can be profitably transferred to poorer pastures. Similarly a young sward requires a few seasons of the-building up cycle before it is cut and thus deprived of a quick return of stimulant. When hay is bought the farm gains in fertility. The value of hay as manure (sometimes its sole virtue) thus varies according to the sward on which it is fed.