POTASH MANURE.

New Zealand Graphic, Volume XLVIII, Issue 16, 16 October 1912, Page 39

POTASH MANURE.

It is well known to cultivators that both garden and farm crops have to be supplied with manures in some form that contain nitrogen or ammonia, phosphate and potash; and that, 'if any one of these is deficient, the results will be more or less unsatisfactory. It is also o'enerally known that there are various sources of nitrogen and phosphate, but that in the case of potash the only sources of importance are the deposits at Stassfurt, in Germany. Notwithstanding the last-named fact, potash 'is a common and widely-distributed substance and it has been estimated that it forms about 2.8 per cent of the crust of the earth. The whole of the potash can be traced back to the original rocks — granite and others of a similar composition —and to the mote recent rocks of volcanic origin. Usually the minerals containing potash are associated with such large proportions of quartz that the percentage of potash is very small. There are, however, in various parts of the world large deposits of rocks and minerals containing much higher percentages. It is essential, in forming an estimate of the value of a material as i, potassic manure, to know not only the percentage of potash, but the condition in which it exists. The importance of this will be understood when it is stated that potash in a soil or manure may be in an available stat ' in wh'ich the plant can take it up at once, or in such condition that some years’ exposure is necessary to convert it into an available state. The availability of the potash is an important factor, as shown by the fact that a clay soil may contain 2 per cent of potash, and that, owing to it not being in a condition for the plant to utilise it, a dressing of soluble potash manure may be necessary to ensure a satisfactory crop. Potassic manures usually employed are kainit. sulphate, ami muriate of potash, and these are so readily soluble in water that the plants can make use of them at once. It is of some practical importance to know that, notwithstanding their solubility, there is, owing to the absorbent properties of the soil very little risk of loss through drainage.—“ Gardeners’ Magazine.”