RESULTS OF EXPERIMENTS.

Otago Witness, Issue 3099, 6 August 1913, Page 16

RESULTS OF EXPERIMENTS.

—Partial Sterilisation of Soils.— In .a second report on their experiments in the partial sterilisation of soils, Messrs E. J. Russell and H. B. Hutchinson, of the Rotharnsted Experiment Station, confirm tile conclusions of their first report, and give further detail. The increase of fertility resulting from sterilising, by steam or by antiseptic fumigants, is attributed to the destruction of protozoa which prey upon the beneficial bacteria of .the soil, with the consequent increase of the latter. At present the authors have not given such details as the quantities of soil fumigants to be applied to a given space, and we believe that their experiments have not yet extended to open fields; nor has the subject of expense been clearly worked out. Of course, the partial sterilisation of fields by steam or any other method of heating is out of the question, and what needs to bo decided is the cheapest soil fumigant with due regard to efficiency. It may prove that the cost of the fumigants fend the ploughing or digging of them in will bo greater than that of a liberal dressing of nitrogenous manure. This, indeed, seems highly probable. ■ —Nitrogenous Manures for Mangolds.— Experiments were carried out in two seasons by the Northumberland County Council to 'test the relative results of different kinds of nitrogenous manure for mangolds, including the two manures derived from the nitrogen of the atmosphere. Four plots each received 2cwt basic slag, 301 b sulphate of potash, and 2< wt salt per acre. Then 5161 b of nitrate of soda per acre was added for one nlo.t, 6161 b nitrate of lime for the second, 4001 b nitrolirn for the third, and 4001 b sulphate of ammonia for the fourth. All four dressings contained 801 b of nitrogen per acre. The yields of the plots receiving nitrate of soda and nitrate of lime were practically equal in one season, wliile the fatter came out first in the other; but it cost u little extra. (Sulphate of ammonia came out third, and nitrolirn fourth. —Manures for Potatoes.— A report from the Irish Depart merit of Agriculture gives the average results of experiments at 353 centres for H years. Where no manure was used the average yield was four tons per acre. The application of 15 tons of farmyard manure increased the yield to 8 tons 4ewt, while 20 tons of the manure increased it to 9 tons 2cwt. Where lewt of sulphate of ammonia was added to 15 tons of farmyard manure the average yield was 9 tons 3cwt. The further addition of 4cwt oi superphosphate brought the yield up to 9 tons 19cwt, and yet further addition of lewt of muriate of potash brought it up to the maximum of 10 tons I7cwt. 'Valuing potatoes of largo or fair size at only £2 per ton and small at only £l. the profit from the use of the last-named mixture of manures was £8 8s 7d per acre. This was the greatest profit, comparing results with those of the uiimanurcd plots; and deducting the cost of the manures. —Sprouted Seed Potatoes.— The average gain in the yield of maincrop notatoes from sprouting the seed tubers* during 10 years, and in 1352 tests in Ireland, was 1 ton 19cwt per acre. —Manures for Mangolds.— The average results of 127 experiments carried out during six years by the Irish Department of Agriculture encourage even more liberal manuring than that which has been recommended in a preceding' paragraph for the mangold crop. The greatest yield and profit resulted from the use of 20 tons of farmyard manure, 4cwt of (superphosphate, 2cwt of sulphate of ammonia, and 4cwr of common sa't per acre. The yield was 33 tons 19owt. as compared with 9 tons 9cwt from the unmanurrd plots. When nitrate of soda was used at the rate

of 2cwt per acre instead of 2cwt of sulphate of ammonia, the yield was reduced by llcwt per acre; but this was probably because it was not applied till after the plants were thinned. Other experiments have indicated that the best results follow application in the drills. Besides, 2cwt of nitrate of soda cost considerably less than the same quantity of sulphate of ammonia, and the profit shown was only Gd per acre less for the former than for the latter. Lastly, in the drier climate of England nitrate of soda more frequently proves superior to sulphate of ammonia than it docs, in rainy Ireland.