HUMUS AND ITS MAKING.

King Country Chronicle, Volume VIII, Issue 706, 23 September 1914, Page 6

HUMUS AND ITS MAKING.

GREEN MANURING AND LIME^j No subject ia of creator importance to the horticulturist than that of providing hiß soil with sufficient humuH, which is vegetable or organic mattor in process of decay. Without humus soil is unablo to retain moisture; it quickly runs together and cakes after rain, and it gives minimum results from the use of commercial fertilisers. Market gardeners and others who carry on their operations in the vicinity of towns obtain their supuly of humus from stable manure; but the crchardist, who, as a rule, can got but little oC this material, hr.s to resort to manuring—that is to a suitable crop grown on the ground and ploughed under where it | stands. There is some difference of opinion as to whether the cover crop should he turned under green or dry, and whether or not repeated green manuring sours the ground. It will bo interesting, therefore, to read the reply of Professor C. B. Lipman, of the University of California to correspndent who puts a series of questions on the subject. "I may Hay," writes the professor, that thus far wo have carried out one experiment; of tho amounts of humus produced from green manures, and we find that about half of the dry weight of the clover material which was used in nur experiments was transformed into humus, as 'determined by the Hilgard method. We find that in a season of about six months, with sufficient moisture in the soil, all organic matter added to the soil is humified or oxidised, so that no recognisable cell tissue remains behind. Most of it is transformed into humus in three months, and more than half of it in six weeks. Vegetable matter is more readily changed to humus whnn turned over mot the soil in the green state than when plouged under dry; at least tiie very scant experimental data which we have on this subject to date justifies us in making that sattement. There is a slight danger of rendering soil which h neutral in reaction acid by repeated gmen manuring. In any case, soil should be kept in a slightly alkaline con lition by the addition of lime, and, especially were green manuring is practised, the use of one to two tons of lime to the acre once in fivo or six years on neutral soil will bo necessary for good crop Ding. In a soil of neutral character, decided benefit in total yield of crops may bo obtained by trie application of ground limestone at the rate of one to two tons to the acre. Such applications do not always manifest the benefit accruing from them by the outward appearance of the crop, but the total weight and nitrogen-content are always affected by the application of lime. Unless a soil under such conditions is well supplied with organic matter, a very finley ground limestone should be employed.