The effects of different levels of N, P and K on the yields, nitrogen content and kernel weights of malting barley (var. Proctor)

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Abstract
SUMMARY The effects of N, P and K applied broadcast on yields, percentage nitrogen and kernel weights of barley were studied over two seasons. The average yield increase over thirteen sites was 5·1 cwt and 8·2 cwt from applications of 35 lb and 70 lb/acre of fertilizer N respectively. A mean yield increase of 4·4 cwt/acre was obtained from 27 lb P at four sites where the soil phosphorus test did not exceed 2 ppm P. Potassium applied at rates varying from 0 to 168 lb K/acre increased yields at one site only and decreased them at another site. The mean grain nitrogen percent without fertilizer N was 1·47 and applications of 35 and 70 lb N/acre gave increases of 0·06 and 0·19% respectively. The overall effects of P and K on the percent nitrogen in the grain were small. Applications of 35 and 70 lb N/acre increased the mean 1000 kernel weights by 0·7 and 1·0 g respectively. When lodging occurred kernel weights were decreased. Fertilizer P and K had little effect on the kernel weights. The significance of these data are discussed in relation to previous cropping and rainfall during the growing season and during the previous winter.