Manure and Fertiliser Requirements of Potatoes on Acid Soils

Abstract

3²' confounded factorial trial was laid down at Gituamba Substation, altitude 2,130 m, in the Long Rains 1979 in order to determine manure and fertilizer requirements of potatoes on acid soils. Nitrogen at 50, 100 and 150 kg/ha N as calcium nitrate, phosphate at 100, 200 and 300 kg I ha P205 as single superphosphate, potash at 0, 100 and 200 kg/ha K2O as sulphate of potash and farmyard manure at 0, 5 and 10 t/ha dry matter were applied at planting in the presence of a blanket dressing of 1 that lime in the form of Magmax. In the first season the total yield of potatoes was equivalent to 17.27 t/ha and only manure had a significant effect on yield, mean plot yields at 0, 5 and 10 t/ha being equivalent ,to 13, 20 and 21 t/ha. In the Short Rains 1979 a residual maize crop which yielded the equivalent of 3.6 t/ha showed significant effects of manure, potash and phosphate in descending order. Potatoes replanted in the Long Rains 1980 with reapplication of all treatments gave a total yield equivalent to 16.22 t/ha. Manure and potash had significant main effects on yield and there was a significant positive KF interaction. The treatments increased available nutrients in the soil and uptake of nutrients by the plants. The results showed that farmyard manure is the best treatment for potatoes grown on acid soils but may be supplemented by mineral fertilizers where insufficient amounts are available.