Art. LXII.—Notes on some Experiments with Chemical Manures.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 29, 1896, Page 588

Art. LXII.—Notes on some Experiments with Chemical Manures. By W. F. Worley. [Read before the Nelson Philosophical Society, 8th June, 1996.] For several years I have carried on experiments with chemical manures in the kitchen garden. The results of most of these experiments have been highly satisfactory. The following manures have been used: Lime, gypsum, bonedust, superphosphate, guano, nitrate of potash, sulphate of potash, sulphate of ammonia, chloride of ammonium, liquid ammonia, caustic potash, and sodium-chloride. The best general results were obtained by the use of superphosphate (home made), nitrate of potash, and sulphate of ammonia. The crops grown were such as are usually found in a kitchen garden, and included potatoes, onions, peas, beans, cabbages, lettuces, radishes, celery, cauliflowers, rhubarb, turnips, carrots, parsnips, mustard, strawberries, currants, gooseberries, apples, peaches, plums, apricots, quinces, and tomatoes.

In the experiments, potatoes, onions, turnips, and radishes gave the best results, although all the above-mentioned were benefited by the application of suitable chemical manures. Watering cabbages with a dilute solution of sulphate of ammonia produced astonishing results, and the application of caustic potash and lime to the roots of apple-trees proved highly beneficial. As most of the crops were gathered in small quantities, as required for daily consumption, no exact record was kept of the amount of produce raised. Rows of potatoes, peas, turnips, &c., however, were manured for about two-thirds of their length, the remaining third being left without manure. The improved crop in the manured portion of the rows proved conclusively in most cases that, although somewhat costly, the manuring of them paid well. In some cases the unmanured portion produced nothing, the labour of digging and planting being quite unrewarded, whilst, on the other hand, there was a good crop on the manured part in return for the outlay in chemical manures. Being anxious to prove for the benefit of others the amount of advantage to be gained by the use of chemical manures, I conducted last year the following experiments :— Arrangements were made with the proprietor of a piece of neglected used-up land for the ground to be treated with chemical manures. For this purpose the land was divided into four sections and planted with potatoes. An unproductive potato-crop had been taken from the land the previous year. No. 1 section was manured with bone-superphosphate and nitrate of potash, at a cost equalling £11 10s. per acre; No. 2 section with bone-superphosphate and sulphate of potash, at a cost of £9 15s. per acre; No. 3 section was manured with bone-superphosphate, sulphate of potash, and sulphate of ammonia, at a cost of £10 5s. per acre; and No. 4 section was left unmanured. The yield from the four sections was as follows: No. 1, at the rate of 19½ tons of potatoes per acre; No. 2, 15¾ tons; No. 3, 14¼ tons; No. 4, 11 tons. The potatoes were sold in small quantities at varying prices, but the average price was equal to about £4 per ton. At this price No. 1 section would leave, after deducting the cost of manure, £66 10s. for labour, seed, and interest on capital; No. 2, £53 5s.; No. 3, £46 15s.; No. 4, £44 (there-being no deduction for manure in the latter case). These comparisons are not, however, strictly accurate, since the potatoes on the manured sections, owing to the stimulating effect of the manure, matured early, and consequently realised a better price than those from the unmanured section; and, further, at least 25 per cent, of the manure used on sections 1, 2, and 3 would be left in the soil, available for a second crop.

If the potatoes had only realised £2 per ton, then sections 2 and 3 would have shown a loss by comparison with the unmanured section. On section 2 there would have been an apparent loss of 5s., and on section 3 a loss of £2 15s. Theoretically, section 3 ought to have come out better than section 2. The manure used on section 3 was the same as that used on section 2, plus sulphate of ammonia, which ought still further to have improved the crop. As section 3 was close to the hillside, probably this fact had something to do with the results. Leaving out of calculation No. 3, whilst the use of chemical manures on section 2 showed an apparent loss of 5s. per acre, section 1, even with potatoes at £2 a ton, would show a profit of £5. 10s. per acre—that is to say, an expenditure of £11 10s. per acre in chemical manures produced 8 ½ tons more potatoes than the unmanured section, or, in Other words, an outlay of £11 10s. produced an increase of £17. But at £4 per ton, which is a reasonable price, an expenditure of £11 10s. per acre would result in thirty-seven pounds' worth of extra produce, or a nett increase of £26 10s. These results, though striking, are, I am sure, quite in harmony with the results that I have obtained on my own ground during the last ten or twelve years, and prove conclusively that chemical manures will pay—on some soils at any rate—if the right kinds are used in the right way. The success obtained in these experiments is largely due to the care exercised in the selection of the chemical manures. The superphosphate was made by myself from locally-prepared bone-dust which had been previously analysed to test its purity, and was used quite fresh before it had had time to deteriorate. The nitrate of potash, sulphate of potash, and sulphate of ammonia were also proved to be of good quality before being used. The potatoes were planted in drills, and the chemical manure, well mixed, was scattered around the sets before covering with earth. — — No. 1. No. 2. No. 3. No. 4. Yield of potatoes per acre 19 ½ tons 15 ¾ tons 14 ¼ tons 11 tons. Value of potatoes at £4 per ton £78 0s. £63 0s. £57 0s. £44 0s. Cost of manure per acre 11 10 9 15 10 5 Balance left for seed, labour, and interest £66 10s. £53 5s. £46 15s. £44 0s.