This is the fourth in a short soil of a Shanghai garden, by Bz. Mond & Ca. (China), Ltd, series of articles on preparing. the Birdwood of Motes, Brunnen, Another method of improving soil is by burning it. This means building up a cairn of earth, scooping out a small hole in the middle at the bottom, stuffing the hole with in-
charcoal, ete., setting it alight, and flammable straw, then walling it in. Combustion will go on slowly until there is nothing more to combust—in theory. Actually this is what you will find farmers doing in certain parts of England, making the most unpromising ma terial burn, and burn thoroughly. One explanation at present popular with certain soil savanta is that the heat destroys harmful organisms bat has little or no effect on the The harmful gentry, certain protozoa, are of a higher order in the micro-social scale than their prey, the useful soil bacteria, who make up for their fatal succulence'by a greater immunity to high temperatures, is assumed of course that the layer or heap of earth is of sufficient thickness to give protection from naked flames, and that the burning is slow and' not fierce. In any case, it is a fact that fired earth, with no fertilizer of any kind added, will show an increase in fertility. for small quantities of earth to be used for potting and greenhouse work.
Green manuring is a most beneficial proceeding for the relief of heavy and impoverished soils. Its drawback is that the ground. fs useless for other purposes while the green crop is in possession unless you are reckoning to sell your seed. Soil deficient in nitrogen, which is the most easily lost of all plant foods, improves to a remarkable degree if a crop of beans be sown and dug in when fully grown, The amount of nitrogen which, for instance, a crop of soya beans can add to one acreshas_ been reckoned! as about 1 cwt, a very large. amount, if it is recollected: that. 6 cent, of sulphate, of ammonia, or 64 cwt. of chile nitrate, or about 7 tons of farm yard manure would be needed to supply the same amounts It is interesting to pull up a fully grown bean plant and study the small nodules on the roots where the nitrogen industry is in full swing, each nodule possessing a quota' of nitrifying bacteria very. much in excess of the population of our largest. manufacturing contres.
The Balanced Diet The foregoing articles have dealt with conditioning processes. which have combined mechanical with nutritive improvement. It now remains to discuss methods of putting plant food into the soil, a branch of "preparation" that appeals to intensive gardeners, A soil which is mechanically cultivated and kept in good condition will ale ways grow stut, bat for a first class show a carefully chosen, con centrated balanced food diet is necessary, This process cannot, of course, be repeated indefinitely, for assuming that the useful soil' bacteria are thereby allowed to increase checked, the soil materials which they attack and break down for the it food will need than they otherwise would.
Tt is not suggested that Shanghai gardeners should make burnt offerings of their neat~ ly kept flower beds and lawns, but the above method is recommended There are several ways of me creasing the food supply in the soil without the addition of bulk, am-angst, the best known concentrated fertilizers being sulphate of am-bonita, nitrate of soda, superphosphoto,' sulphate and muriate potash, dri addition there is a cone stantly increasing range of s0-callod' Dalanced mixtures which are a8 0 rule balanced for only one crop and table for any other. ily follow, because different species need different pro~ portions of the three principal food elements, nitrogen, phosphoric acid and potash. A horticulturist who really knows his job will always want to mix his fertilizers himself, tat the same time there are very few. people with sufficient time to acquire this thorough knowledge and who will therefore do better to get their fertilizers ready mixed from a relia ble firm who state exactly for what purpose the mixture is intended, In two concluding articles the the various functions of the above three elements, nitrogen, phosphoric acid and potash will be discussed from the point of view of sell preparation, with special reference to the application of artificial op chemical fertilizers—C. T. Brno wood.
Text read from the printed page and cleaned; old type leaves the occasional error.