SOIL FERTILISATION

Southland Times, Issue 17656, 14 February 1916, Page 6

SOIL FERTILISATION

LECTURE BY MR D. L. FREEMAN. THE LIME CONTROVERSY. There was a good attendance of farmers at Limehiils on Thursday evening last, when Mr D. 1.. Freeman, the Southland Education Board’s agricultural instructor, delivered a lecture on soil fertilisation. Mr W. A. Cox, provincial president of the Southland Farmers’ Union, presided. In the course of his remarks, Mr Freeman said that one of the most urgent requirements of the Southland farmer was a better knowledge of artificial fertilisers. Considering that in the main the farmer relied on their use, it was essential that lie acquired the requisite information. There were, he said, ten plant food elements which the plant required before it could mature. These were:—-Carbon, hydrogen, oxygen, nitrogen, phosphorus, lime, iron magnesium, and potassium. He referred to the, main services of these elements, and said that sulphur had been applied to crops with good results, and that iron was sometimes applied also in the form of fertiliser by the fruitgrower, particularly to stone fruits, and with good results. There was sufficient lime present in most soils to enable crops to roach maturity. Lime was valued more for its indirect effects. It was found ttiat nitrogen, phosphorus and potassium were usually most deficient in soils, and this had resulted in concentrated manures being placed on tHe market. These v. ore knownfs artificial fertilisers. Those supplying nitrogen were Known as nitrogenous fertiliser; those supplying phosphorus as phosphatic fertilisers; and those supplying potassium as potassic fertilisers. He then dealt with the different NIT BOG lONOUS FERTILISERS. Those included nitrate of soda, sulphate of ammonia, dried blood, calcium cyanamide, and calcium nitrate. Nitrate of soda contained 1 5 y 2 per cent, of nitrogen, i.e., 'lit Vj lbs per 100 lbs of fertiliser. Sulphate of ammonia contained 20 per cent.; dried blood, 10 to 13 per cent., and calcium nitrate, 13 per cent. The two latter were new manures, the nitrogen contained in them being derived from the atmosphere. Nitrogenous fertilisers had a tendency to promote the growth of leaf, stem and root, at the expense of the seed. Comparing nitrate of soda and sulphate of ammonia the farmer, lie said, was the quickest in action, and .should ho applied as a top dressing when the plant commences to grow vigorously. Tire effect could he seen within a few days. The main plant food it contained was in a form in which it could easily be assimilated by the plant, while that in sulphate of ammonia had to undergo changes before the plant could make use of it. This fertiliser should be applied at the time of sowing the seed. Nitrate of soda applied tr. grass lands encouraged the growth of deep-rooted and coarser grasses at the expense of the finer. In most seasons nitrate of soda would give the pest results. It v. as considered by some that sulphate of ammonia would be better in a wet season, hut that was not always - found to be the ease. Nitrate of soda in a diw - season would diffuse more readily in the soil, and would bo effective in encouraging deeper rooting. Dried I>l nod was a slower acting manure, r ml would produce good quality pro--1 ncr. Of the TWO NEW MANURES, caic’imi cyaiKiinhie compared favourahly wilh sulphate of ammonia in regard to its effects upon tin. - crop. Calcium nitrate was about as quick acting as nitrate of soda. Regarding phosphatic fertilisers, those which concerned the Southland farmer included superhphosphato, basic superphosphate, basic slag, bonodust, steamed bone flour, and phosphatic gun nos. Superphosphate was prepared by treating phosphatic rock with acid. For land containing sufficient lime this was the Pest kind to apply. The fertilising innjor:.a I contained in it was in a readily avtvilablc form. Basic phosphate was prepared in 1901 by adding sufficient lime to superphosphate to change the

mouscaicic, or one lime phosphate, to dicalcis, or two lime phosphate. It was claimed that it was more effective on sour land. Air Freeman considered it the better plan to lime the land and use superphosphate. Of the lime fertilisers ho recommended the use of steamed bone flour, as it was free from fat. and, therefore. was more readily acted upon and made available. Unlike nitrogenous fertilisers phosphatic fertdisers had a tendency to hasten ripening, establish a good root system, and consequently it had had the effect of promoting deep rooting and earlier ripening on the wheat crops in Australia. Of the potassic fertilisers sulphate of potash, muriate of potash, kainit. and MO per cent, of potash salts were the most important. The effect of potash fertilisers on a crop was important in connection with earlier assimilation of the plant, in strengthening the plant tissue, and in rendering the plant more immune from disease. In many soils it aws unnnecessary to apply potasslc fertilisers, especially ricli heavy soils, and land on which timber had been recently burnt off, Snnrly and gravelly soils required most potash. In average soils sufticicnt could be liberated by the applied t.on of lime, and of nitrate of soda. This dispensed with the purchase of expensive potassic fertilisers. Referring to THE PURCHASE OF FERTILISERS.

Mr Freeman said that they were valued on what was known as the unit system. He demonstrated on a blackboard how to determine the values of nitrogenous, phosphatic, and potassic fertilisers. Before artificial fertilisers could exorcise their full influence, certain conditions had to be fulfilled. It was necessary, he said, that land .should he well drained, and that it contained sufficient l:me and decayed vegetable matter. He referred to some beneficial effects resulting from drainage, and said that decayed vegetable matter was the last fertiliser of all. It supplied all the food necessary for good crop production. It also improved the texture of soils, making them easier to cultivate, and enabling a better seedbed to be produced at a less cost. Another important condition to be fulfilled before fertilisers could produce the’r full effects was that of sufficient lime content of tho soil. Lime was continually being lost from the soil to the subsoil in the forms of chloride, sulphate nitrate, and bicarbonate of lime. Soils benefitting most from applications of lime were heavy soils, those containing an abundance of vegetable matter, e.g., peaty soils. Newly drained soils required liming, also newly reclaimed lands and pastures where white clover is absent. Besides being a plant food itself, lime liberated other plant foods in tho soil. It liberated potash and nitrogon,\and was useful in regard to phosphates. it prevented the formation of the insoluble iron and aluminium phosphates. It might even bo instrumental in bringing aluminium and iron phosphates, if already formed, back into tho form of the more soluble and MORE READILY' AVAILABLE limo phosphate. Lime corrected sourness in soils, assisted bacterial action, and was useful in regard to plant diseases. Lme also rendered certain harmful forms of iron and copper compounds harmless. Of the different kinds of lime on the market, burnt lime in tho lump and ground forms, and ground limestone most concerned tho Southland farmer. Two tons of burnt lime contained as much lime as 3V6 tons of ground limestone., Taking the casp of a hill of limestone containing 3500 tons, this when burnt was concentrated, and 1500 tons of carbon dioxide gas was driven off. Thus 2000 tons of burnt lime would result. Both kinds of limo carried out similar work, but the burnt product was more energetic in its action. Assuming that farmers in a district used burnt lime in preference to the unburnt product, instead of carting on to their land 3500 tons at a cost of £3500, they would cart 3000 tons only at a cost of only £2OOO, ami they would still have the amount of lime. Two thousand tons of burnt lime when applied to the soil would absorb 1500 tons of carbon dioxide, and form 3500 tons of carbonate of lime in tho soil. QUESTIONS. Replying to questions, Mr Freeman said that it was more economical to apply lime in small dressings annually. For Southland land which had been limed, a substantial dressing should at first be given. He advocated distributing by means of tho lime spreader. The advent of white clover on grass land, to which nitrate of soda had been applied, lie attributed to the liberation by tie nitrate of soda of soil potash. Mr Freeman was accorded a very hearty vote of thanks for his interesting and informative lecture.