GREEN MANURING AND USE OF FERTILISERS.

Otago Witness, Issue 3114, 19 November 1913, Page 15

GREEN MANURING AND USE OF FERTILISERS.

Tlio system of green-manuring to furnish a supply of organic matter, and to collect nitrogen from the air—in the case of the green-manuring crop being leguminous,— can be employed with decided advantage on sandy soil, and 'also on medium soils, for fields to which it may not bo convenient to apply farmyard manure. To get the best results from green manuring it is necessary to supplement ft by tho application of fertilisers. On this subject a distinguished German professor of agriculture has the following observations:— 0 (a) Application of Nitrogen.—The necessity for the addition of nitrogen is dependent on the success of tho green crop and on the requirements of the following crop. I 1 or instance, if the green crop has grown well, potatoes and cex'eals on good or medium soil should not require tho help of any additional artificial nitrogen. Following a poor green crop, it may be advisable to give either potatoes or cereals, especially oats,, the benefit of a top-dressing of lewt nitrate of soda. Mangolds following a green crop will certainly require some quick-acting nitrogen, and should have a dressing of 2cwt to 3cwt nitrate of soda. (h) Phosphate of Lime.-—A small dressing of superphosphate is advisable to increase tho effect of tho green manuring. For roots and potatoes tho soil should receive liewt to 2cwt per acre; cereals a little loss —lewt per acre should suffice. (c) Potash.—The addition of this ingredient plays a very important part with jrreen manuring, especially in root-growingT With cereals it is not so essential. The following exaople serves to show the necessity of applying artificial potash to roots and potatoes grown on green-manured land. . In. experiments at Lachstadt the increase of crop produced by the application of potash with a green crop ploughed under

(peas, beans, and vetches) was six tons of roots and four tons of potatoes. Thus :t appears that roots and potatoes can only make full use of the stuff ploughed under w’hcn the crop has a dressing of potash as well.

(dj Farmyard Manure. —It might be considered superfluous. to apply farmyard manure with green manuring. Such docs not, however, appear to be the case, and in practice good results have been obtained by it. This may be due, not to the actual plant food in the farmyard manure, but to the great activity which it produces in the useful bacteria life, and this increased activity helps to the utility of the green manure. The dressing of farmyard manure should be quite moderate, as a big application would nor be required, and would be wasteful.