THE SOIL.

Nelson Evening Mail, Volume XLVII, Issue XLVII, 4 March 1912, Page 6

THE SOIL.

POTASH SALTS. The demand for potash salts, especially for kainit, is enormous at the present time throughout Europe. The factories and depot at Stassfurt are so pressed with orders, both for home consumption ■and export, that there is difficulty in dealing promptly with the rush of business. It 16 now generally recognised that kainit, in order to get the best results from its use, should be applied quite early, late in autumn, or during the winter. The more concentrate * salts, sulphate of potash, can be anplied in the spring, although with them, it has been noticed that the benefit i 6 most marked when they are put in the soil a. month, before the seeds are sown. Potash salts are the supplement of nitrogen and phosphoric acid. To employ these two latter plant foods year after year, and to neglect- potash, is to run the risk that the crop may suifer. There is an equilibrium between the three plant foods —nitrogen, phosphoric acid, and potash—and unless this balance is maintained it is not possible to obtain the maximum crops and the profit which should accrue from a proper system, of intensive cultivation.

There is lime and lime—lime properly adapted for agricultural purposes and lime not suitable for application to the land. A recent Journal of the British Board of Agriculture has a paragraph on the subject. A case lately came to the notice of the Board in which a grey lime was sold for agricultural purposes which proved on analysis to contain, in addition to 68 per cent of lime and 1.33 per cent of magnesia, as much as 16.6 per cent of insoluble siliceous matter. While such a lime would be suitable for building purposes ,it would be quite unsuitable for use on the land, as. on being wetted, it would tend to set like cement. It is doubtless unusual for lime having so large a content of silica to be sold for agricultural use, as purchasers would readily detect its unsuitability for slaking, but farmers would be well advised when buying this material to ask for a statement as to the amount of siliceous matter present. In purchasing burnt lime, quicklime, lime shells, or caustic lime (all terms for one and the same materi. al), a guarantee should be obtained that it contains not less than 85 per cent of pure lime and not more than 4 per cent of magnesia. It may be noted in this connection that the expression pure lime, oxide of lime, oxide of calcium or calcic oxide, sometimes made use of by sellers of lime, all have the same meaning. Ground lime consists of burnt lime ground to a fine powder, and should" be similar in quality to quicklime. Ground limestone, an the other hand, is limestone rock —that is, more or less pure carbonate of lime —ground to a fine powder. Wheal tho purer limestones are used for this purpose the percentage of carbonate of lime may b c expected to exceed 95 per cent.

An experiment which shows the efficacy of whitewash as a. remedy for t-hrips has been made by Earl L. Morris, horticultural commissioner of Santa Clara County, in the pear orchard of W. C. Bogen. of San Jose. A solution of simple whitewash was sprayed upon two rows of trees, and the third row left without spraying. This treatment was carried out on a sufficiently large proportion of the orchard, so that none of the results obtained could be attributed to differences of light or soil. The result was an overwhelming demonstration of the value of whitewash as a remedv for this fruit pest. When the fruit was picked last week it was lound that the sprayed trees produced eight times as much as those which had not been treated, and thb fruit was larger and free from blemish. The snrav is composed of 801bs of lime to 100 eallons of water, and is applied liberally to the trees 'ust as the thrips begin to appear. This point of applying at the proper time is the main essential of success. The treatment has also been aoplied to prunes with good results.