Page:Notes on five years' experiments on hop manuring conducted at Golden Green, Hadlow, Tonbridge.djvu/6

4 hop-growers, who regularly used a variety of more or less concentrated nitrogenous manures, chiefly of a slowly-acting kind, such as shoddy, woollen rags, hoof and horn-parings, feathers, fur trimmings, and the like, have systematically neglected the use of phosphatic manure. Those who used rape dust, fish guano, and purchased dung have, indeed, in the form of these manures, been applying phosphates to their land, but still in quantities quite insufficient to balance the nitrogen contained in the fertilisers used; and it is, comparatively speaking, only in recent years that the use of really phosphatic manures, such as superphosphate, dissolved bones, Peruvian guano, bone dust, or basic slag, has tended to become at all general among hop growers.

For years past the supply of nitrogen, being excessive in relation to the supply of phosphates, was limited in its utility; and though, when it was in the form of such slowly-acting manures as those above enumerated, the excess might often do little harm, yet, if the excessive quantity of nitrogen, unaccompanied by phosphates, were supplied in the more active form of sulphate of ammonia, or in the still more active form of nitrate of soda, the plant would naturally be encouraged by the abundance of soluble nitrogenous food to make a rapid growth that was incapable of being carried to a proper conclusion, on account of the lack of mineral food. Such spasmodic and irrational manuring might naturally be expected to produce a forced overgrowth of bine and inferior hops. Such cases, however, are in no way applicable as precedents in considering the action of soluble manures like nitrate of soda and sulphate of ammonia, when applied in conjunction with proper quantities of phosphates, potash, and, if necessary, lime.