Effects of fertilizers and dung on potatoes

Abstract

Field experiments were carried out in north-east Scotland on potatoes to measure the responses to, and the two-factor interactions between, nitrogen, phosphate, potash and dung, and have given the following results:1. The responses to nitrogen, phosphate and potash are quite variable from centre to centre, but the mean results show moderately large increases to all three nutrients.2. The mean responses to both nitrogen and phosphate are the same in the presence as in the absence of dung. The response to potash is reduced by two-thirds in the presence of dung.3. There is a general trend for both nitrogen and potash to increase the linear component of the response to phosphate and vice versa. Nitrogen and potash show practically no interaction effects.4. Dung produces a considerably larger increase in yield in the absence than in the presence of fertilizers.5. The nitrogen and potassium contents of the tubers show appreciable effects of the nitrogen, potash and dung treatments.6. Suitable fertilizer dressings are suggested for potatoes grown in the absence and presence of dung.