INTERCROP PERFORMANCE OF PEARL-MILLET, AMARANTH, COWPEA, SOYBEAN, ANDGUAR 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 th is study was to apply intercropping principles to alternative and trad itional crops in the USA under mechanized conditions, Although these c rops hare been examined in intercropping systems, in most cases studie s were not conducted with improved varieties found in the USA or in st rip widths that can accommodate machinery. A field study was conducted at two central Missouri locations in 1991 and 1992 to determine the e ffect of intercropping on grain yields of pearl millet [Pennisetum gla ucum (L.) R. Br.], amaranth (Amaranthus hypochondriacus L. x A, hybrid us L.), cowpea [Vigna unguiculata (L.) Walp.], guar [Cyamopsis tetrago noloba (L.) Taub.], and soybean [Glycine max (L.) Merrill], Treatments were assigned in an incomplete factorial design and consisted of plan ting 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, soybea n, or guar) and a nonlegume (pearl millet or amaranth). In the strip i ntercrops, only cowpea showed a consistent yield response to planting pattern, with the narrow strip arrangement with amaranth yielding 53 a nd 39% lower than its monocrop in two environments. Land equivalent ra tios of amaranth and pearl millet groan 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 u pon 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.