BASIC-SEPERPHOSPHATE.

Southland Times, Issue 20526, 30 June 1928, Page 14 (Supplement)

BASIC-SEPERPHOSPHATE.

A USEFUL FERTILIZER. MIXING PROCESS OUTLINED. (Written for the Southland Times.) A number of years ago when, owing to disturbed financial conditions, fertilizers were selling at an exorbitant price, some farmers commenced to make their own fertilizer mixtures. Some mixtures were good, and others could be correctly described as diluted mixtures, as some sellers of proprietary mixtures described them. A large proportion of lime or of carbonate of lime was used, and farmers who were ignorant of fertilizer analyses mixed as much as fifty per cent, of carbonate of lime with fifty per cent, of superphosphate, and made no allowance for dilution when the application was made to the crop, and I have heard that in the north a similar mixture had been sold at the price of superphosphate. If that is a fact, the buyer ignored the analysis, and he had no clear idea of the function of superphosphate. Some people think that one cannot have too much of a good thing, but the good things in fertilizers are nitrogen, phosphoric acid and potash. These are the plant foods that we need to apply, and it is because phosphoric acid is the scarcest plant food and the one that is most largely removed in ' seeds, meat and milk that farmers have to use more of the phosphatic than of the nitrogenous and potassic fertilizers. Lime in any form is certainly very important, but our soils have enough naturally to supply the very small amount that is required by crops and pasture plants as food. Lime is used to improve the condition of the soil, and is therefore described as a soil improver. The importance of buying fertilizers according to analyses can be shown in this way. A 36-38 per cent, superphosphate contains 16.49, a genuine basic superphosphate 14.01, and a mixture of equal parts of superphosphate and carbonate of lime 8.21 per cent, of phosphoric acid respectively. A unit of phosphoric acid in superphosphate costs just now about 5/6, and it will readily be seen that these mixtures vary a good deal in value per ton. The values are approximately £4 10/6, £3 17/-, and £2 12/- respectively, including in the cost of the last named seven shillings worth of carbonate of lime. The quantities required per acre for, say, a 25-ton crop of turnips would be about 2cwt., 2^cwt. and 4 cwt. respectively. The object in making basic-superphos-phate is to remove the acidity caused by the sulphuric acid, and no more lime should be used than is required for that purpose. Basic-superphosphate costs more than plain superphosphate owing to the additional labour connected with its preparation, and I think that it is now generally held that basic super is not required where lime in any form is applied either before or during the application of super. At the time (1901) that Hughes, an English agricultural chemist, introduced basic-superphosphate it was believed that superphosphate was an acid manure, but few authorities hold that opinion now. Wrightson and Newsham, in their work on "Agriculture,” published in 1919. say that the "the neturalization of soluble monobasic phosphate in the soil ought to be sufficient answer to those who blame the ‘acidity’ of superphosphate as the cause of finger and toe and other ailments in root crops. All fertile soils are alkaline in reaction. An acid fertile soil is scarcely imaginable. . . It therefore seems improbable that a dressing of superphosphate, which is instantly rendered alkaline and converted into dibasic phosphate, can exert any corroding or injurious effect on a growing crop.”

In making basic superphosphate, or basic super for short, the first process is the slaking of the lime. Lime is slaked on a wooden or concrete floor with one-third of its weight of water. It should be turned over a few times with a shovel. After about, four hours it is cool enough for handling, and should then be riddled with a one-fourth inch mesh riddle in order to remove the underburned limestone, which may amount to five per cent, or more. The material then exists in a fine dry powder like flour and is ready for use, or it may be bagged and kept for future use. Slaked lime does not damage the bags. The next process is mixing on a wooden or concrete floor 151bs of slaked bme with 851 b of super, that is 3301 b slaked lime and 19101 b of suner to the ton. The materials should be mixed with the shovel till the mass is of uniform colour, and left on the shed floor at least 24 hours to cure. It is then ready for use, or for bagging and storing for future use.

Inferior mixtures of so-called basic super are made with various amounts of ground lime or of ground carbonate of lime. The important thing to remember is that basic super made with either of these forms of lime in large proportions are “diluted mixtures” worth much less than the genuine article.

Some ground North African rock phosphates are called “basic phosphates” because they contain lime in excess of that which goes to make up the phosphate compound, 142 parts phosphoric acid and 168 parts of lime. The rock phosphates, guanos and bones supply the same plant food as super., but not in the immediately available form. They are, however, when finely ground available in a reasonable time and there is economy in their use mixed with super for the short-lived crops and mixed or separatelv for the longer lived pasture plants. Bones contain, in addition, some nitrogen. BABY BEEF. POSSIBILITIES ON LONDON MARKET. AN EXPERTS VIEWS. It is the opinion of Lieut.-Colonel T. D. Young (veterinary inspector for the City of London), who is visiting the Dominion at the invitation of the New Zealand Government, that a mistake is being made by producers of the Dominion in withholding their cattle from the market until they reach four or five years of age. In Argentina, he states, it is customary to send cattle to the market when about two years and six months to two year and nine months of age. What is wanted is a small bullock,, small boned with plenty of meat on its carcase, and fat distributed equally over the carcase, such as the Polled Angus type. The animal should possess a useful carcase, and be not too big or fat. It would pay a producer better if he could put two animals on the market in the same time as he now puts one. he states.

Colonel Vouny stressed the necessity of dehorning cattle for export, such as had been done for years in the Argentine. In the North Island, he said, he had seen a great amount of damage done to carcases through bruising from cattle that were not dehorned. He had, in fact, been shocked to see how greatly some of the carcases had been knocked about in this respect. Asked what he thought of the stock he had seen so far in the Dominion, Colonel Young said that he was unfortunate in that his visit to the Addington yards was made at a time when only the culls of the season were being offered for sale, and consequently did not see the best representatives of the lambs produced here. He had, however, seen some very fine lambs in the North Island, and there was no doubt that better lambs were produced in the Dominion than in the Argentine or Australia. He thought that a lamb bred from a Romney ewe and a Southdown ram was the best that could be produced. An English Leicester ram and a suitable

also lent themselves to the production of a good type of lamb. Colonel Young considers that more care should be taken by the men working on the carcases than is done in New Zealand works. They should endeavour to dress them better than is done for marketing purposes. He believes that the New Zealander engaged in such work is a good man, but is inclined to rush his work too much in this respect, instead of taking the time over it that is taken in South American works. He states that if he were employed in the Argentine and did similar work there he would soon have his services dispensed with.

Colonel Young stated that the most modern works he had seen in the Dominion were in the North Island, the improvements which were being effected at the Tomoana works (Hastings) striking him as being designed to bring them right up to date. The Gear Company’s works, Wellington, were also fairly modern. But there was no comparison between the works in the Dominion and those in the Argentine. This was easy to understand, for in South America the works had been erected more recently than those in operation in New Zealand, and it had also to be remembered that there was no seasonal killings there as was the case in New Zealand. At the Union Cold Storage Company’s works at Buenos Aires, for instance, there was provision for killing as many as 4,000 cattle, 5,000 to 6,000 sheep, and 1,000 pigs per day.