WORK AT ROTHAMSTED.

New Zealand Herald, Volume LXVIII, Issue 20987, 25 September 1931, Page 16

WORK AT ROTHAMSTED.

FIELD AND LABORATORY.

" BALANCE" IN MANURING.

STUDY OF PLANT NUTRIENTS

In the annual report of tlie Pothamsted Experimental Station there is a record of a tremendous amount of detailed work conducted both in the field and in the laboratory. The conclusions of the year's experiments on the effect of fertilisers on farm crops are given and related to tho results obtained in previous years. This section forms for specialists, students, and progressive farmers an authoritative statement of the present position with regard to fertiliser experimentation in England.

As an example of the field work on fertilisers we may take a potato experiment of 1930, in which the point under investigation was the effect of the "balance" of the various nutrients on the yield and composition of the crop. This is one of the most fruitful kinds of experiment, because, although the necessity for the nutrients has been widely demonstrated, there is little information about the proportions necessary to give the best results. This experiment, liko most others, showed the interdependence pf the manures supplying nitrogen, potash arid phosphoric acid. Nitrogen and potash mutually increased each other's effect, while the two together markedly increased tho effectiveness of phosphoric acid. ol Farmyard Manure. The variety of potato planted was "Ally." There were two sets of experiments, both in the same field and with the same variety. In one the maximum yield was 11 tons, in the other, with equally efficient mixtures of artificial fertilisers, it was 7 tons only. The heavyyielding crop had had farmyard manure, tho other had not. In general one would not have expected so marked a difference. But in 1930 the crop receiving farmyard manure continued growing well throughout the latter part of the season, while (he crop without it weakened early and became smothered in weeds, mainly chickweed (Stellnria media). The yield without nitrogen, like.that without potash, was 4 tons per acre. This was raised to 7 by the heaviest dressings of artificials. The number of plants per acre averaged 14,760. In the other set the crop gave a yield of 7.5 tons from farmyarjl manure without any artificials. One cwt. sulphate ot ammonia gave an additional 30cwt. of potatoes as also did I.6cwt. sulphate of potash so long as sufficient superphosphate was given, otherwise the increase was onjy 24cwt. Superphosphate (3ewt. per acre) gave the very satisfactory increase of 36cwt. of potatoes per acre so long as there was sufficient nitrogen and potash; with insufficient quantities the increase was only 11 cwt. ESects of Nitrogen. The potatoes at Woburn (also Ally) yielded even better than at Rothamsted, giving up to 13 tons per acre. The most marked effects were from nitrogenous manuring; phosphatic and potassic fertilisers had less effect, contrary to expectation on this light soil. In another experiment icyanimide and sulphate of ammonia were found equally effective as also were superphosphate and basic slag, compared on the basis of equal amounts of nitrogen and of phosphoric acid respectively. Another experiment indicated, like the one at Rothamsted, that a certain amount of sulphate, in the forms of sulphates of magnesium, potassium and calcium, had been beneficial; larger amounts, however, were not. Similar work x on yield and quality is recorded for barley, sugar beet, forage mixtures and grassland. Next are described two new rotation experiments, started in 1930 and intended to be continued for a period of years. One is designed to test various alternative methods of returning to the soil tho straw grown on the holding and also provides a comparison of rock phosphate with superphosphate. The other, conducted bo<th at Rothamsted and Woburn, brings out season by season the effects on six different crops of a scries of doses of the common nutrients, and will eventually form the basis of the study of the effect of season on fertiliser action. Work in the Laboratory. Work in the field by no means exhausts tho activities of the station. Much of the report deals with tho object and results of thd varied laboratory investigations on plant nutrition and plant. disease. Many of these are highly technical, and are, at present of purely scientific interest. Nevertheless, sue!) work is necessary for the future solution of technical problems. A few of the lines of work which have direct contact with practice may bo mentioned. The results of scientific study of the nodule bacteria of tho lucerne plant has now been carried into practice, and artificial inoculation of lucerne seed according to a technique de vised at Rothamsted is commonly carried out by growers of this crop. Over 4000 acres of lucerne was sown down with inoculated seed during the period covered hy the report. A further application of microbiological research is to be found in the artificial rotting of straw and other vegetable wastes hy' the controlled activities of fungi and bacteria. This is widely used iri the preparation of organic manures at home and in other countries," and the product. is being exhaustively tested in tho field experiments. The course of decomposition is being further studied. Physics Department.

In the Physics Department a systematic study of soil cultivation is being made with the object of putting this costly item in the farmer's expenditure on a scientific footing. A beginning has heen made, with a detailed examination of the effects of rotary cultivation. The physical action of tho treading of sheep, so important on light land farms, is also being studied. In the. Department of Plant Pathology the most extensive investigation is concerned with the so-called virus diseases, which seriously damage a wide range of economic crops. This 1 is a problem of such complexity that systematic research from many points of view will be necessary before practical results can be expected, and a team of specialists is engaged in the work.