MANURES AND MANURING

Taranaki Daily News, 7 May 1934, Page 11

MANURES AND MANURING

ADDRESS BY MR. J. M. SMITH. RESULTS GLEANED FROM PRACTICE Manures and manuring formed the subject of en address, illustrated by slides, given by Mr. J. M. Smith to a representative gathering of farmers at Leppertdn on Saturday night, from observations gleaned from experimental plots, and farm practice in Taranaki. Mr. Smith explained the reasons for manuring, pointing OUt that the natural fertility of the soil, Which had been depleted to' a large extent by farming Operations, had to be replaced as far as possible by, artificial means. It was Nature’s intention that each year the fertility. df the soil should be increased, but man in his wisdom and with progressive ideas had with the axe, the fire stick and the.plough brought about a set Of conditions whereby the fertility Was becoming, exhausted. In an. acre of soil a foot deep, which weighed approximately 140 tons, there wore 15051 b. of potash and 3761 b. of phosphates. There were three essential plant elements—potash, phosphate and nitrogen. .There were other elements, but they would hot be exhausted for several generations. Soil analysis would not give an ihdication of the amount of the necessary elements in the soil that was available for plant use, though at times soil analysis was valuable in determining local outstanding problems. It also determined the acidity of the soil, which was a good guide to ascertain the amount of lime required to counteract that sourness.

Mangolds, sWedes and Other root crops depleted the natural soil fertility much more rapidly than did the growing of wheat and Oats. Dairying, too, depleted the soil much more quickly than did grazing. There was a. drain on the potash element in the soil, which explained the necessity for adding fertility. Soil fertility depended on three things—the mechanical, Chemical and biological condition of fhe soil. The last-named referred to whether dr not the bacteria was working actively and beneficially to make the plant food available, and he showed hoW nitrogen was made available. Some fertilisers stimulated the bacteria. Warm and sweet conditions were required for beneficial bacterial action, and that Was Why acid conditions in Soil were not desired. Improvement in the plant soil could be expected by the addition of substances containing plant food or of substances that would liberate plant food and make it available to the plant. In phOSphatic manures the phosphoric acid content was what Counted, and that amounted to 5-llthS of the total phosphates. High-grade slag had about the Same percentage of phosphoric acid as had superphosphate. The latter, however, Was 100 per cent, soluble in soil water, While 92 per cent. of basic slag was so soluble. The soil water must be slightly acid or plants could not flourish. Two per cent, of citric acid was adopted as the international basis for the solubility of phosphates in soils. PERCENTAGE OF LIME. The percentage of lime in the soil depended on how much of the phosphate reverted and became slowly soluble. That was the. reaton why if superphosphate was used heavily lime must be used Once every three Or four years to prevent the super being too quickly soluble in the soil, so that it could not be used by the plant, in which case it was wasted. Lime must be used to ensure that the phosphate was held. in the soil and became slowly available to the plant. He..eXplained at length the manufacture of superphosphate and the average analysis of high-grade superphosphate which formed the basis of 'the majority of proprietary mixtures, every one of which had to be registered. They iVere all analysed. The Government was there- [ fore ensuring that a high standard of fertiliser Was supplied to the farmer. Slag manufactured in England on the I Open hearth system Was Of lower grade than that manufactured on the Bessemer system in Belgium. The principal ingredients of slag were lime and phosphoric acid. A certain percentage of the lime was free. There was also iron oxide and Other minerals in slag, and it Was probably one Of those other ingredients that accounted for the suc-

cess that followed the use of slag in North Taranaki, as the excessive rainfall could not account for all the difference as compared, say, with South Taranaki and Waikato. It might be said that the use of slag stimulated the clovers at the expense of the other grasses, but he did not consider that with the use of good strains Of rye, etc., there was any need to fear that the continued use of slag Would unbalance a pasture, Grinding of phosphatic rock did not increase the percentage of the potash that was soluble, but it did make the percentage that was soluble available the more rapidly for the plant. Mr. Smith thought bone dust and green bone were manures that Could be safely used, as they were good foundation manures Containing slow-acting soluble phosphate, which fed the plant a long time. The lecturer then explained the Various potassic manures, stating that sulphate of potash, while twice the price of 30 per Cent, potash, did not contain twice the available potash. In North Taranaki the position had been reached where there was a d.ire necessity 'for potash. Dairying took considerable potash from the soil, and while phosphates had been replaced for Some years, potash had not been applied. NITROGENOUS MANURES. • There were several nitrogenous manures, continued Mr. Smith. These included sodium nitrate, sulphate of ammonia, calcium cyanamide, nitrate of lime, blood and bone and nitto chalk. He considered calcium cyanamide Would become popular. However, there would be no need to worry about nitrogenous manures aS long as the’clover content of the pasture was kept up. Rain also brought nitrogen to the soil. Nitrogenous manures would assist in bringing grass along out of season. Several highly-concentrated manure mixtures were made on the Continent. There were certain basic principles in the mixing, of manures. Super could be miked with any manure except Slag, and it could even' be used with the latter, providing that it was used at once, Any manure with lime in it should not be mixed with sulphate of ammonia, but nitrate of Soda could be mixed With any manure.

Farmyard manure was the nearest to nature atld Was the most neglected, remarked Mr. Smith, who stressed the necessity for the proper Utilisation, of animal manure. At the present time when finance was tight and it was difficult to secure artificial fertiliser a lot could be done to utilise droppings by harrowing the pastures, Animal nitrogen was very Valuable to the soil.

Sowing the best Strains of rye, clover, etc., would enable a dairy farmer to obtain an ideal pasture, but such' a pasture required fertilising to maintain it. Poor pasture poOrly fertilised would cost mdre to produce a pound of butterfat than would a good pasture well fertilised. The programme for fertilising should be to endeavour to have the pastures growing evenly throughout the year, but as that dairy farmer’s Utopia Was not possible, fertilising must be carried out so as to produce grass a little earlier in the spring and to carry it on a little later into the winter. Fertilising in April and May, also in the summer or early autumn, was therefore advisable.

Experimental plots in various districts showed What manures should be used, in what quantities and when they should be used in those districts. There were 50 or 60 plots at present in Taranaki, and those were being increased, So that in time if Would be possible to draw up a comprehensive map of Taranaki and its fertiliser requirements. Super and slag each had their advantages, but at present prices he considered the Use of Super Would prove the more economical. Palatibility of pastures following manuring was an important feature, aS it affected utilisation. For growing early, nitrogenous manures Were Valuable. In using fertilisers a general principle to follow Was that for root crops or grain phosphates should dominate the mixture, whereas for green food nitrogenous manures should dominate. No manuring would make up for lack of cultivation in connection with root crops. Mr. Smith exhibited a series of slides showing tabulated results gleaned from the recent competitions in regard to the benefit of the various manures used and their quantities. Subsequently a discussion' took ■ place, numerous questions being answered by

Mr. Smith. Mr. Smith was accorded a vote of thanks, the chairman stating that his lectures were always interesting and contained a lot Of new matter. Prior to the address the monthly meeting was held, when two new members were elected—-Messrs. R. Cortriett and L McDonald, the latter being a junior member. Several entries were received for the pasture competition.