A comparison of the effect of rainfall on spring- and autumn-dressed wheat at Rothamsted Experimental Station, Harpenden (With Five Text-figures.)

Abstract

The effect of rainfall on the wheat crop grown on Broadbalk has been investigated, special attention being paid to the time of application of the nitrogenous manures.In the years 1854–77, when plots were manured solely in the autumn, the average decrease in yield caused by each additional inch of rain is greater than the average decrease from 1854–1918. The difference in this case cannot be ascribed to the change in manurial treatment.The period of 24 years was too short to allow seasonal variation in the effect of rain to appear, as it was only possible to compare such seasonal variation with that of 1854–1918 in the case of one plot. In this case it was observed that summer rainfall was more detrimental to autumn-dressed than to spring-dressed plots; this result was confirmed by studies of the effect of rain on the difference in yield of two plots which differed only in the time of application of their manures.