Land Equivalent Ratio

It means one unit of intercropped land produces the same yields of its component crops as 1.4 units of land would under sole cropping. Equivalently, the intercrop saves 40 percent of the land needed to grow the same amounts of each crop separately. The 1.4 is built by adding each crop's intercrop yield divided by its sole-crop yield, so a value above one signals a land-use advantage and the amount above one quantifies it. A value of one means no advantage, and below one means the mixture is less land-efficient than sole crops.

Because the components of an intercrop usually have very different absolute yields and units — a cereal grain versus a legume, for instance — so they cannot simply be added together. Dividing each crop's mixture yield by its own sole-crop yield converts every component to a dimensionless relative yield, the land fraction it would occupy alone to match its mixture output. These relative yields are commensurable and can be summed. This normalization is the heart of the LER, and it is why the choice of an appropriate, like-for-like sole-crop benchmark is so important.

Not necessarily. The LER measures biological land-use efficiency only; it weights all yields by their sole-crop benchmarks, not by their market value. A mixture can have an LER above one yet be less profitable if it shifts production toward a low-value crop, or be economically attractive despite a modest LER if it favors a high-value component. For economic decisions the LER should be complemented by gross-margin or partial-budget analysis that prices the actual yields, so biological and economic advantage are assessed separately and then weighed together.