Potato/maize intercropping in the Jos Plateau of Nigeria

Abstract

In the short rainy season at Jos, Northern Nigeria, the potato is invariably intercropped with a variety of cereals and legumes. Field experiments were conducted in 1984–1987 at this site to quantify the yield and economic benefits associated with this practice. The four series of experiments determined the population densities of Solanum potato and maize, time of introduction of maize, compatible cultivars of potato, and level of N and P 2 O 5 for optimum yields of produce and revenue in potato/maize intercropping. In Experiment I, three potato populations (33, 24.75, 16.5 × 10 3 stands ha −1 ) and four maize populations (33, 24.75, 16.5 and 8.25 × 10 3 stands ha −1 ) were studied. Total tuber yield of potato, at each potato population, declined with increasing population of maize. Maize yield, however, was not significantly affected by increases in the potato population. Sole potato gave higher net return than either sole maize or any potato/maize combination. Highest net return from potato/maize intercropping was obtained at planting densities of 24.75 × 10 3 potato and 16.5 × 10 3 maize per ha. In Experiment II, maize was introduced into potato at 0,1,2,3, and 4 weeks after planting potato. Potato yields increased with delay in the introduction of maize, while maize yields decreased as its sowing date was delayed. The optimum time for introducing maize into the potato crop was 2 weeks from planting. Experiment III compared the compatibility of two potato cultivars of different maturity ratings and growth habit with maize. Yield of maize was more suppressed by the later-maturing RC 777-3 than by the early-maturing B 9462-1. The results indicate that late-maturing potato varieties with semi-erect growth habit may be unsuitable for intercropping with maize. A complete factorial of 6 levels of N and P 2 O 5 (0,20,60,90,120 and 150 kg ha −1 ) was used in Experiment IV to determine optimum levels of fertilization for the intercrop. For maximum yield of potato (the base crop), calculated levels of N and P 2 O 5 were 97 and 119 kg, respectively. However, for optimum profit, calculated application rates for the nutrients were 98 kg N ha −1 and 72 kg P 2 O 5 ha −1 . The application of these results to similar conditions elsewhere is discussed.