Fertilizer levels for intercropping: effects of nitrogen on maize in sole cropping and intercropped with cowpea under soil water deficit

Abstract

The effects of different levels of nitrogen on maize yield, in sole cropping and intercropped with cowpea, were studied during three successive rainy seasons in the semi-and area of Pernambuco State, Brazil, in a low-fertility Red-Yellow Podzolic Planosol (Terra Bruna Estruturada). The experimental design was in randomized complete blocks with four replicates in the first and third years and three in the second year. The treatments were 0, 40, 80, 120 and 160 kg/ha of N. The results showed variations for the three years, apparently as a result of the markedly different seasonal moisture conditions. There was no response to the nitrogen applications and the highest nitrogen levels had a detrimental effect on the yield of sole maize. Intercropped cowpea yields were 30% to 53% lower than in sole cropping. The yield for intercropped maize was very low corresponding to only 1/3 of sols maize. The calculated Land Equivalent Ratio (LER) was less than one for all the nitrogen levels.