Effects of high levels of fertilizer on yield of potatoes grown for ware

Abstract

SUMMARYNine experiments in the East of Scotland were completed in the years 1966, 1967 and 1968 to test the response of potatoes grown for ware to five levels of a 15½–15½–21 fertilizer applied at rates of 0, 4, 8, 12, 16 and 20 cwt per acre.1. Mean yield of ware tubers increased up to the highest fertilizer level.2. Mean yield of small tubers increased only up to the 8 cwt per acre level and then declined.3. Dry matter content of ware tubers decreased with increasing levels of fertilizer.4. Increasing fertilizer levels lowered soil pH. At one site this was associated with a significant reduction of common scab on the tubers.