Experiments on the availability of phosphates and potash in soils / by J. Walter Leather.

  • Leather, J. Walter (John Walter), 1860-1934.
Date:
1907
Catalogue details

Licence: In copyright

Credit: Experiments on the availability of phosphates and potash in soils / by J. Walter Leather. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    indicate that there is no such immediate necessity. For root crops, especially turnips, the limit would probably be higher.” (Page 269.) “ In the paper on the Hoos Field barley soils a tentative conclusion was drawn that the percentage of citric-acid-soluble potash in surface soil, indicative of potash hunger for cereals, would probably be below ‘005. On considering the results of the wheat soil analyses and other results obtained in the interim by other workers who have applied the method to other soils known from other experience to be responsive to the influence of potassium salts, the author would now be inclined to modify this conclusion by suggesting that when a soil shows as much as ‘01 per cent, of citric-acid-soluble potash, by this process, it may be regarded as not demanding any special application of potassium salts.” (Page 275.) There is one point which must be referred to here. One of the first questions* raised, after the publication of Dyer’s first paper, was in relation to calcareous soils. Obviously the calcium carbonate present in soils will forthwith react with the citric acid resulting in the formation of calcium citrate and carbonic acid, and the soil is then in contact with a solution of these substances together with any excess of citric acid. In order to illustrate the bearing of this point, the following figures show the quantities of calcium carbonate in a soil which neutralize each tenth part of the citric acid employed ; or since 10 grms. of the acid are employed per 100 grms. of soil, the figures show the percentage of calcium carbonate neutralized by each 1 grm. of the acid. Citric acid. Calcium Carbonate. Grms. Grms. 1 • • • ... T43 2 • • • ... 2'86 3 Ml ... 4-29 4 • • • ... 5-72 5 • • • ... 7'15 6 ... 8'58 7 Ml ... 10-01 8 • • • ... 11-44 9 • • • ... 12-87 10 • • • ... 1430