9
the residue of the dung applied in 1895 must have been the sources drawn upon, though for two years previously these had sufficed to produce but little more than half a crop. The phenomenon observed on this one-sixth of an acre is no doubt due to the same natural causes that produced the abnormally heavy crop in 1899 over a large area in Kent and Sussex; and it is of great interest to inquire what these causes may have been.
One of our plots which, without chemical fertilisers, has every year received thirty loads of London dung per acre, had given in 1897 and 1898—when the summers were very dry—almost as bad an account of itself as the plot altogether destitute of nitrogenous manure, producing quite a paltry crop compared with that produced by phosphates, potash, and nitrate. In 1899, however, this dunged plot behaved in an altogether exceptional manner, and did as well for quantity as any of our plots, producing 24½ cwt. of hops per acre, though, as we shall see, the quality was poor compared with that of the nitrated and phosphated hops. The same natural influences, therefore, that produced the extraordinary yield of over a ton per acre on the nitrogen-starved plot produced still more marked results on the dunged plot.
I think that much light is thrown on the matter by going back to 1898, and considering the weather then experienced. We had in 1898 a very hot summer, followed by an unusually warm autumn, affording a long and favourable time for the natural nitrification of the organic nitrogen of the soil, so that the land must have been unusually well supplied with natural nitrates by the time that winter arrived, if, indeed, the term winter can properly be applied to such mild weather as was experienced during the calendar winter months of 1898-99.
