Intercrop Performance of Pearl Millet, Amaranth, Cowpea, Soybean, and Guar in Response to Planting Pattern and Nitrogen Fertilization

Intercropping is a common practice in developing countries because it may produce higher total yields than monocropping. The objective of this study was to apply intercropping principles to alternative and traditional crops in the USA under mechanized conditions. Although these crops have been examined in intercropping systems, in most cases studies were not conducted with improved varieties found in the USA or in strip widths that can accommodate machinery. A Held study was conducted at two central Missouri locations in 1991 and 1992 to determine the effect of intercropping on grain yields of pearl millet [Pennisetum glaucum (L.) R. Br.], amaranth (Amaranthus hypochondriacus L. × A. hybridus L.), cowpea [Vigna unguiculata (L.) Walp.], guar [Cyamopsis tetragonoloba (L.) Taub.], and soybean [Glycine max (L.) Merrill]. Treatments were assigned in an incomplete factorial design and consisted of planting pattern (monocrops, narrow and wide row strips, and alternate row intercrops), N fertilizer (0, 56, or 112 kg N ha⁻¹), and component crop combination. Each intercrop consisted of a legume (cowpea, soybean, or guar) and a nonlegume (pearl millet or amaranth). In the strip intercrops, only cowpea showed a consistent yield response to planting pattern, with the narrow strip arrangement with amaranth yielding 53 and 39% lower than its monocrop in two environments. Land equivalent ratios of amaranth and pearl millet grown in alternate rows with cowpea were not significantly different from their monocrops. At the Columbia site, yields of alternate row intercrops generally did not increase upon addition of N and in 1992, amaranth yield at 0 kg N ha⁻¹ was 25% higher in the alternate row intercrop than it was at the same N rate in the monocrop. In general, grain yields were similar in the various intercrops compared with monocrops. Contribution of the Missouri Agric. Exp. Stn. Journal Series no. 11,862.