FRUIT GROWING

Wanganui Chronicle, Volume 74, Issue 144, 20 June 1931, Page 8 (Supplement)

FRUIT GROWING

MANURIAL TRIALS

EFFECT ON PLANT FOODS YIELD AND QUALITY The question of quality in fruit is an important one, for of all classes of primary production, fruitgrowing is definitely the class in which it is essential and profitable to grow' a quality product. An English writer recently told of experimental work carried out at Long Ashton, the Rothamsted of the fruit world. Briefly summarised the article laid stress upon the importance of the amount and the balance of the potash and the nitrogen supplied to fruit trees. It was shown that, although the nitrogen supply must be maintained, excess of this material as compared with potash prevents the fruit from colouring up well and also lowers its ability to withstand cold storage. Excess of potash over nitrogen gives a fruit of excellent colour and flavour, of good keeping qualities in cold storage, but of relatively lowered keeping qualities at ordinary temperatures. Balance Between Ingredients. The lesson taught by this work is one that must bo learned by all agriculturists, namely, that the secret of plant feeding is one of balance between the ingredients. This fact has been demonstrated in a striking manner at the Cawthron Institute, Nelson, and while the work there has been of more local application, the recommendation of the institute for growers in Nelson province should be studied by fruitgrowers all over the Dominion. In one orchard, there was an annual application of about 6cwt. per acre of a fertiliser mixture containing 12J per cent, phosphoric acid (as superphosphate), 6 per cent, potash (as sulphate), and 3 per cent, nitrogen (as sulphate of ammonia). Additional nitrogen was supplied by the growth of blue lupins iu January, which received half the superphosphate used. The total production of apples represented an increase from 175 bushels an acre in 1926 to 352 bushels an acre last year. This was on a fair type of sand loam. Yield and Quality Improved. On a typically poor Moutere Hills soil, the result of a progressive manurial plan has been to increase the production from 187 bushels to 300 bushels an acre. In this case the dressing an acre was higher, consisting of a total of about 14cwt. an acre of a mixture containing 10 per cent, phosphate, 61 per cent, potash and 74 per cent, nitrogen (half blood and half sulphate of ammonia). Even assuming that this

mixture would cost as much as £lO an acre applied, the increase in yield alone (113 bushels an acre) would show a handsome profit, but it is also reported that the quality was improved to as marked an extent as was the yield. On soils of higher fertility the type of mixture varied slightly. The Stoke country —typical orchard soil not very different from the Central Otago country —the recommendation was for about 7cwt. per acre of a mixture containing about 8 per cent, each phosphoric acid, potash and nitrogen. The contrast between these mixtures and mixtures of the type regularly sold in New Zealand as orchard mixture -is striking. One taken at random from 20 price-lists has the one-sided formula of 20 per cent, phosphoric acid, 2.85 per cent, potash and 1.5 nitrogen. All Plant Foods Needed. Phosphoric acid is admittedly the predominant plant-food requirement for the average crop on the average soil in New Zealand. Fruit is, however, so sensitive a crop that even though the natural supplies of nitrogen and potash in the soil are higher than the natural phosphate, the addition of large amounts of available phosphate without corresponding additions of potash and nitrogen may lead to a lowering of yield on quality. Dr. A. Jacob, a well-known German agronomist, points out that “although phosphoric acid is so important to the formation of flower-buds, their early development cannot be induced by applications of phosphatie fertilisers alone, but only when sufficient nitrogen and potash are also present.-” The moral of this is obvious. A progressive manurial plan must be adopted and adhered to. This must aim at supplying the tree with an adequate amount of each plant food. Feed the tree well and generously and, in yield and quality of fruit, the tree will repay.