THE FARM.

Marlborough Express, Volume XLI, Issue 135, 10 June 1907, Page 6

THE FARM.

CARROTS AS A FIELD CROP. A good crop of carrots is always an acceptable field crop. They are most useful in more ways than one. There is always a brisk demand for them at a higher price than any other root that ■is grown on the farm, and as stock food in health or sickness there is none better. For sickly animals, and those disposed to reject other foods, carrots are always an excellent change. There is never a cry of too many,but a shortage is often very much felt. Ihe crop is not one I would advise on heavy, stiff land. The roots must penetrate and develop into clean specimens, and when forked and twisted they are not good, neither are the roots that are perforated with worms, and precautions must be taken to prohibit their depredations. A sandy soil is best for carrot-rgrow-ing, and those with such would do well to^devote a few acres to them, both for home use and selling. Early in April is the best time to sow the seed The soil must be deeply cultivated, and no lono- manure should be used, bhort material is admissible, but if the soil is m good heart, this too should be left out. Useful fertilisers are _ 4cwt of superphosphates, 2cwt of kainit, and 3owt of soot per acre, all sown broadcast a-n£ deeply harrowed in. All should be drilled in rows about 20m apart and 2in deep. They should be drilled as thin as possible, and it the seeds cling together, as sometimes is the case, rub them apart before putting in the drill. After sowing, and when the surface is dry, it should be rolled firmly, They can be hand or horse hoed when a few inches high, and must be thinned out to 6m apart before they become crowded. PHOSPHATE OF LIME. This substance is known under several names—as mono-calcium phosphate or one-lime phosphate, acid phosphate, superphosphate. The process of treating rock phosphate or bones with sulphuric aoid is, as stated, for the purpose of converting the triealcium phosphate in these materials into the soluble mono-dalcium phosphate. By this process the sulpnurie acid combines with two parts of lime, forming-sulphate of lime or gypsum; the water .of the acid taking the place of the lime which has been removfed. This gives a compound which contains one part of lime and two parts of water, in combination with the one part of phosphoric acid which was contained in the tri-calcium phosphate. This substance is very soluble in water, and readily diffuses in the soil. In making this material the whole of the insoluble phosphate is not acted upon, for to render all of it soluble ■would require the addition of an excess of sulphuric acid, which would prove injurious to plant life. The tri-cal-cium phosphate which. remains after the treatment with acid when left in contact with a comparatively large amount of soluble phosphate causes a reversion of some of the soluble material, which gives more or less of the other form of phosphate called "reverted " or . " gone-back " phosphate. The quantity- of soluble phosphate present in acid phosphate varies somewhat,but it should contain from 13 to 16 per cent., the amount depending chiefly upon the materials, from which it has Jbeen made. Acid phosphate carries; a" considerable quantity of gypsum; eaoh 100 pounds containing usually between 50 and 60 pounds. This material has some value as an indirect fertilising material, and its presence in the phosphate should not be neglected, especially by those who often think it necessary to use gypsum in making different complete fertiliser mixtures, or in making complete fertilisers which contain acid phosphate. The soluble phosphate, being very soluble, and therefore readily diffused ■in the soil, is the most valuable form of phosphate for plant food. Although it is easily dissolved by the soil water, it is not leached out as several constituents of the soil, such as humus, lime, iron, and aluminium compounds, have the power of fixing and retaining it for the use of plants.