The investigation bears out the conclusion of the Rothamsted experiments that leaching out may occur any time throughout the winter up to March, or rarely April.

The loss of nitrates is directly limited by the amount of drainage and so is indirectly determined by the rainfall, and by temperature—as it affects the rate of evaporation.

All three nitrogenous fertilisers are shown to lose well over 50 per cent, of a normal dressing by leaching out during the winter, but the loss is greatest in the case of sulphate of ammonia, least in the case of rape dust, calcium cyanamide being intermediate.

The writers wish to express their indebtedness to Miss N. Sugg who carried out the experimental work in the first winter.