Stimulating Plant Growth

Sun (Auckland), Volume III, Issue 756, 31 August 1929, Page 35

Stimulating Plant Growth

Value of Nitrogen ‘ THE dairy produce output of the Morriusville district for 1 the season just ended is greater than that from the Uaihi goldmine in its palmiest year. Railway freight - c tut ns for fertilisers show an increase of over ten per cent, on those of the previous year.”—Recent news item. Mornnsville is not the only district to register a big increase in production following the judicious use of fertilisers. The experience is common to manv districts of New Zealan d.

The most progressive farmer now realises that the soil has certain very clearly defined wants; that the most satisfactory plant growth can only be expected from a soil fed with fertilisers balanced to meet its separate requirements. The qvestion of cost is not first today; the man who gets 1 he best results is he who uses fertilisers which have been specially prepared by experts who understand local needs and conditions. That is why the product of New Zealand manufacturers 'will always have a big lead over importations. A soil ingredient which is receiving more attention in these days of increasing is n !i —'gen. As a plant food and a stimulant it will promote growth in the cold weathei and will cause grass to grow so quickly as to make it necessary to increase the number of stock to keep it down. It stands to reason, however, that if the grass is going to register a faster rate of growth, apart from using up more nitrogen it will use more of the other essential plant foods, phosphate and potash. A very important point arises here and that is that there must not only be on hand a supply of phosphoric acid and potash to keep pace with applied nitrogen, but the phosphoric acid and potash must be offered to the plant in just as tempting and readily digestible a form as the nitrogen. The average phosphate application of many New Zealand farmers is probably high enough to balance that amount of nitrogen necessary under the new system. Just what the ratio between nitrogen and phosphoric acid should be. has never been exactly determined, but indications so far point to equal parts as a suitable ratio for grass—i.e., a ratio of 1 to 1, with a minimum for New’ Zealand pastures

of from 3cwt to 4cwt an acre of a 20 per cent, phosphoric acid fertiliser.

Nobody can yet say how much potash is required to balance a given quantity of nitrogen. The farmer can only endeavour to make sure that there is at least a sufficiency available in the soil. Heavy soils, e.g., clay soils, usually contain a large percentage of potash, but not necessarily in an available form, although it may be made available by the application of sufficient quantities of lime. Therefore, don’t attempt to stimulate grass with nitrogen on heavy soils unless you either—(a) lime sufficiently; (b) apply some available potash. The safest course to follow is to do both. Light soils do not usually contain much natural potash, and therefore, no amount of lime or gypsum can free it. The only solution in this case is to apply potash. Therefore, to adopt the new treatment of grassland with nitrogen involves special attention to certain points. Among other things, such as a different management of the pastures it involves; (1) Expenditure of money for nitrogen, the dearest plant food; (2) the application of at least as much phosphoric acid as nitrogen; (3) liberal liming on heavy lands and potash applications on light lands. The application of the various plant foods may be made in several ways; it remains for the farrnei to choose the most economical and that which he considers likely to be the most efficient. Separate applications may be made as follow;- —Phosphates in any of the well-known forms in spring or autumn, or both; potash.—a little on heavy lands, increasing as the land becomes lighter—say, once or twice a year; nitrogen—in the form of a purely nitrogenous manure like urea sul-

phate of ammonia, three or four times a year. N.8.—(1) Nitrogen must be applied more often than need be the other two plant foods, because it is not only applied more in the nature of a stimulant, but is apt to leech and be lost after a few months have elapsed. (2) The various sources of the separate plant foods may be mixed at the factory or on the farm, and distributed together, thus reducing the number of applications from, say, seven or eight to three or four. (3) Two or three plant foods may be applied together in the form of a complete fertiliser, such as leunaphos IG and nitrophoska IG; the former contains nitrogen and phophoric acid in equal parts, and the latter, the three plant foods in tlie ratio nitrogen, phosphoric acid, and potash—--1:1: I}. The last-named method not only has the advantages which the second offers, namely, of halving the number of applications, but it avoids mixing costs, and as these two synthetic fertilisers are relatively highly concentrated, the method saves freight and cartage. The last tw r o methods have a further advantage, and that is, that the two or three plant foods are applied actually together, and thus there is less danger of the grass or plant suffering through its inability to obtain sufficient of any one of the plant foods to balance the stimulation due to the others.