In India , as many as 84 different crops are used in mixed cropping, but seldom do we find more than four at a time, and a relatively simple mixture of only two or three crops is most common. The main consideration for mixing crops together is to reduce the risk of failure. The farmer reasons that if several crops are grown at the same time, at least one will survive to harvest. But there are other reasons too. This helps spread labour needs more evenly.
Food crops are usually mixed with cash crops to help ensure both sustenance and disposable income.
Cereals and legumes are often mixed, probably more for dietary reasons than for any beneficial effect that the nitrogen-fixing powers of the legumes convey to the associated cereal crop or to a subsequent one. The crops may be grown as random mixtures, but in India they are generally grown as intercrops with a few rows of one component regularly interspersed with a few rows of another. Although research on intercropping may have started to provide an understanding of why the farmer used such mixtures, and to help improve his productivity in ways relevant to his practice, it has now been shown that intercropping may have several advantages over sole cropping. It appears to make better use of the natural resources of sunlight, land, and water. It may have some beneficial effects on pest and disease problems, although the overall results are somewhat inconclusive.