The effect of time and rate of application of nitrogen fertilizers on the yield of wheat

Although it is well known that application of nitrogenous fertilizers to wheat often results in considerable increases in yields of grain and straw, and while experiments at Rothamsted and Cambridge have been very valuable not only in demonstrating the magnitude of the yield increases but also in showing how nitrogenous fertilizers bring about these increases, there is singularly little experimental evidence available regarding the increases in yield which may be expected in other parts of the country. Further, there is very little experimental evidence as to the optimum time of application of nitrogen, except at Rothamsted and Cambridge, both of which are in relatively dry districts.