Fertiliser requirements of potatoes in relation to kind of soil and soil analysis

Responses of maincrop potatoes to N, P and K fertilisers were measured in 119 experiments done by Soil Scientists of the National Agricultural Advisory Service in the years 1955‐62. The experimental sites were spread over 13 soil groups, most of which corresponded to particular soil series.

Average crop responses to P and K are given for each soil group. The amount of response was related to soil texture and to content of soluble P or K in the soil. For a given content of soluble P in the soil, crops on loamy sand and sandy loam soils gave a larger response to the first level of P fertiliser (0.5 cwt P2O5 per acre) than did those on silty loams, clay loams and clays; but the additional response to the second level of P fertiliser and, consequently to the optimum dressings of P, was greater for crops grown on the heavier‐textured soils. P response was also related to depth of freely drained soil, sites with impeded drainage giving larger responses to P than freely drained sites.

The proportion of soils poor in K, crop responses to K and optimum dressings of K fertiliser were all greater for the loamy sands and sandy loams than for the silty loam, clay loam and clay soils.

The optimum dressings of N and K for almost all the soil groups were less than the average amounts currently used on maincrop potatoes in Great Britain; however, the seasons seem to have been relatively unfavourable to N and K responses. For P, the average amounts used were less than the optimum for most of the silty loam, clay loam and clay soils but more than the optimum for most soils of lighter texture.
RESP-5555