Area Harvests Equivalency Ratio for Measuring Efficiency in Multiseason Intercropping

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Abstract
Both area and time factors have to be considered to quantify resource‐use efficiency in multiseason intercropping. The land equivalent ratio (LER), commonly used as an indicator of efficiency, is not suitable because it considers only the area factor to estimate intercrop advantages. The area time equivalency ratio (ATER) unrealistically assumes continuous crop growth throughout the year, thus it underestimates the advantages of intercrops. To avoid these problems, some authors used the mean value of LER + ATER as an arbitrary compromise. This paper proposes a new concept called area harvests equivalency ratio (AHER). This ratio incorporates the time factor in the form of number of possible harvests of each component crop in a system that could be obtained during the full intercrop period, if each component was monocropped. Four cases of intercrops were used to compare the above concepts. The AHER has proved to be a better efficiency indicator than others, except when a component species occupies the land for one season plus a fraction of the succeeding season (l.5, 2.5 seasons). In this particular case, other concepts are also disappointing. The problem with any attempt to quantify resource‐use efficiency is that there is no “true value” for yield advantages in intercrops. However, intuitively, AHER does seem to be nearer to the “true value” than others.