Yield intercropping

Intercropping may facilitate weed control if intercrops are more weed competitive than sole crops or are able to suppress weed growth through allelopathy (the weed species is more susceptible to such phytotoxin than crops). If intercrops do not suppress weeds more than sole crops, they should provide yield advantages due to better utilization of resources or by converting resources than in case of sole crops (Liebman and Dyck 1993). 

An example, when intercropping suppressed the weed growth more than sole, is a leek (Allium ampeloprasum var. porrum (L.) J.Gay) - celery (Apium graveo-lens L.) intercrop sown in a row-by-row layout decreased relative soil cover of weeds by 41%, reduced the density and biomass of groundsel (Senecio vulgaris L.) by 58% and 98%, respectively, and increased the total crop yield by 10% (Baumann et al. 2000). Increased weed suppression and the crop yield were also demonstrated in cereal-legume intercrops in many different environments (Ofori et al. 1987). 

Rusinamhodzi L, Murwira CHK, Nyamangara Cl (2006) Cotton-cowpea intercropping and its N2 fixation capacity improves yield of a subsequent maize crop under Zimbabwean rain-fed conditions. Plant Soil 287 327-336... 

Non-crop plants associated with the crop species offer possibilities for allelopathic weed control. In this study Brassica campestris (wild mustard), which is an important weed in Santa Cruz County, and broccoli, a common crop, were intercropped, The allelopathic potential of both species and the changes in this potential throughout their life cycle were demonstrated with experiments in the laboratory. Effects of different planting densities and sowing time of canpestris on the crop yield are analyzed. Preliminary steps to separate the physiologically active compound(s) are described. The possibilities for the use of Brassica campestris in agroecosystem design as a non-crop plant that promotes pest control are described. 

Chemical analysis of sweetgum seedlings treated with fescue leachates showed that growth inhibition was associated with an impaired absorption of phosphorus an nitrogen. Obviously, conditions of decomposition, allelochemical enhancement of disease, the nature of the secondary products from microbial activity, and interactions among allelochemicals are all significant variables in intercrop allelopathy. The uniqueness of the chemical environment for each crop sequence and situation will continue to confound precise analyses of effects on yield. 

O. is thus the highest-yielding oil crop. Planting density should be 8-9 m, with legume intercrop-... 

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