Intercropping cereals with N-fixing legume species: a method for conserving soil resources in low-input systems

The natural resources of the developing world are becoming increasingly threatened as the agricultural sector intensifies. A major resource being lost is the topsoil. Low levels of soil organic matter and the incomplete ground cover commonly associated with intensive cultivation are two of the major factors leading to accelerated soil erosion (Brady 1974). In the medium-term, soil fertility may be maintained with the application of inorganic nutrients. Intercropping with species that can help to control soil erosion (Langdale et al. 1992), and/or utilize symbiotically fixed nitrogen instead of inorganic sources (Tomar et al. 1988, Danso and Papastylianou 1992), may be a more sustainable approach to the problem. This study examined the benefits of intercropping wheat and barley with N-fixing legume when soil resources are both scarce and unstable. High altitude, rainfed environments, such as subsistence communities in countries of the high Andes or the Himalayas (Weismantel 1992), are frequently characterized by fragile, highly leached soils and a lack of infrastructure precluding the use of external inputs. Most of the current work was conducted on the Central Altiplano of Mexico, where wheat and barley are grown with relatively low inputs, under rainfed conditions, and at a mean altitude of 2250 masl (Byerlee and Longmire 1986). When intercropped, both crops generally yield lower than they do in monoculture, although the land equivalent ratio is often higher in comparison to the monocrop (Papadakis 1941, Ofori and Stern 1987). We tested the hypothesis that, for barley and wheat growing at suboptimal levels of nitrogen fertility, unused radiation can be absorbed by an N-fixing intercrop without detriment to the main crop. Furthennore, we wished to demonstrate that the legume could provide a number of alternative benefits: extra ground cover, a source of animal forage, a source of grain-legume for human consumption and/or a substantial input of organic matter and nitrogen to the soil, either as a green manure crop or indirectly in the fonn of crop residues or animal wastes.

Bibliographic Details

Main Authors:	Reynolds, M.P., Sayre, K.D., Vivar, H.
Format:	Research Report biblioteca
Language:	English
Published:	CIMMYT 1993
Subjects:	AGRICULTURAL SCIENCES AND BIOTECHNOLOGY, CEREALS, LEGUMES, SOIL CONSERVATION, SOIL MANAGEMENT,
Online Access:	http://hdl.handle.net/10883/1178
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