Page:Notes on five years' experiments on hop manuring conducted at Golden Green, Hadlow, Tonbridge.djvu/7

5 As I have also before pointed out, another source of distrust of nitrate of soda is no doubt the fact that it has been frequently applied too late in the season, with the result of delaying the ripening period, a result which, in many seasons, is, as hop-growers well know, highly undesirable.

That nitrate of soda possesses any specific direct influence on the hop plant, apart from what is due to its ready availability and concentration, is an idea for which there would seem to be no foundation. Ultimately all other forms of nitrogenous manure are converted into nitrate in the soil. Some—such as woollen rags, horn shavings, or hoof-parings—are only converted into nitrate after a considerable time; fish guano, rape dust, and dried blood require less time; and sulphate of ammonia, and the ammonia salts in guano, require still less, being chemically much nearer to the nitrate stage. In warm and moist weather these latter are converted into nitrate with fair rapidity, and there is no chemical difference between them and nitrate when they actually reach that stage of plant food.

It would seem, therefore, that if nitrate of soda has in some hands proved hurtful, it is (1) because it has been applied without a proper quantity of phosphates or potash, or (2) because it has been applied too abundantly, or (3) because it has been applied at the wrong time.

In the experiments at Hadlow, we have been endeavouring to solve the question as to the extent to which it is possible to profitably apply nitrate of soda to hops, and when it is best applied. For this purpose, it has been necessary to make the experiments as simple and as free from complication as possible, and no attempt has been made to compare the results obtained from nitrate of soda with those which would