Productivity and risk evaluation in constrasting intercropping systems

Abstract

Four contrasting intercropping systems, sorghum (Sorghum bicolor (L.) Moench)/pigeonpea (Cajanus cajan (L.) Millsp.), groundnut (Archis hypogaea L.)/pigeonpea, sorghum/pearl millet (Pennisetum americanum (L.) Leeke), and groundnut/pearl millet, were evaluated along with sole crops from 1979 to 1982, each year in nine different situations spread over different soil types and agronomic managements, with the objective of analysing the productivity and risk associated with these systems. Productivity of intercrops was closely related to the diversity of the crops involved. The two pigeonpea-based systems, with an interval of about 3 months between harvests of the crops, showed a large and consistent advantage over the respective sole crops. On the basis of land productivity, sorghum/pigeonpea averaged 49% and pigeonpea/groundnut 53% advantage over their respective sole-crop yields. In economic terms, these intercrops were also more profitable than the respective sole crops. The other two systems, with only 2–4 weeks' difference between harvests of the components, showed a much lower and less-consistent advantage. The groundnut/millet recorded 18% advantage and the sorghum/millet 7% over their respective sole crops. Risk was measured by calculating the probability of success or failure of intercrops in satisfying specified quantities of yields or income in comparison with an optimal shared sole system having some of both sole crops. Pigeonpea-based intercropping systems were less risky than shared (or optimal) sole crops over a wide range of expected yields or income. There was no advantage for the sorghum/millet intercropping compared with the shared sole crops at lower expectation, and for higher expectations sole sorghum should be preferred to the intercrop. Risk from groundnut/millet was less than from the shared sole system only in limited situations. Reduced risk of pigeonpea-based intercrops was associated with higher productivity and lower variability of combined intercrop yields or income. The methods employed in this study can be extended for risk evaluation in other intercropping and mixed systems.