ACTION OF MANURES

Wairarapa Times-Age, 23 May 1938, Page 3

ACTION OF MANURES

CULTIVATION BENEFICIAL It is well known that nitrogen works quickly and, if not taken up almost at once, may readily be washed down and out. Phosphates and potash are held in the soil, but it a little disconcerting to be told by the scientist that relatively little of what we apply of these ingredients is ever recovered by the plant. Sir John Russell says that the most he has ever found in the crop is 25 per cent. The phosphate and, to a less extent, the potash, remain in the soil, but undergo a change so as to become unavailable to the plant. Sir John believes in direct applications of manure to each crop according to its requirements, and appears not to have much faith in residual values. However that may be, it is undoubtedly possible for fertility to accumulate, and clovers are not the only agents concerned. Perhaps some of the locked-up phosphate and potash would be released by cultivations —one reason for not leaving grass down indefinitely.