Mixed cropping is growing of two or more crops simultaneously on the same piece of land. It is also known as multiple cropping. This type of cropping leads to an improvement in the fertility of the soil and increases in crop yield. The products and refuse from one crop plant help in the growth of the other crop plant and vice-versa. Mixed cropping is an insurance against crop failure in abnormal weather conditions.It also helps the farmer to improve its yield and economy and avoid crop failure which was very common in India and Asian countries.
By planting one line of one crop, then a line of another crop, both crops can get better. In one line a legume and in another line the main crop. So, if the main crop takes the nitrogen from the soil, the legume fixes the soil. Nitrogen is fixed in the root nodules of the leguminous plants in the form of nitrates (soluble form of nitrogen) and keeps the soil fertile. This helps the farmers to produce more and more crops without the nitrogen being depleted from the soil.
Mixed cropping is not the same as crop rotation. In crop rotation you plant different crops in the same field in different years. Some plants add nitrogen to the soil, some take it out. If you would plant the same crop year after year, you wear out your soil.
Multiple-cropping patterns are described by the number of crops per year and the intensity of crop overlap. Double cropping or triple cropping signifies systems with two or three crops planted sequentially with no overlap in growth cycle. Intercropping indicates that two or more crops are planted at the same time, or at least planted so that significant parts of their growth cycles overlap. Relay cropping describes the planting of a second crop after the first crop has flowered; in this system there still may be some competition for water or nutrients. When a crop is harvested and allowed to regrow from the crowns or root systems, the term ratoon cropping is used. Sugarcane, alfalfa, and sudangrass are commonly produced in this way, while the potential exists for such tropical cereals as sorghum and rice. Mixed cropping, strip cropping, associated cropping, and alternative cropping represent variations of these systems. See also Agriculture; Agronomy.
Another simple definition of mixed cropping:
Mixed cropping is a type of agriculture that involves planting two or more of plants simultaneously in the same field. In general, the theory is that planting multiple crops at once will allow the crops to work together. Possible benefits of mixed cropping are to balance input and outgo of soil nutrients, to keep down weeds and insect pests, to resist climate extremes (wet, dry, hot, cold), to suppress plant diseases, to increase overall productivity and to use scarce resources to the fullest degree. Agronomists studying mixed crops have had mixed results determining if yield differences can be achieved with mixed versus crops that are singularly cultivated. If a combination of say, wheat and chickpeas works in one part of the world, it might not work in another. But, overall it appears that measurably good effects result, when the right combination of crops are cropped together.
The classic example of mixed cropping is that of the American "three sisters", maize, beans, and cucurbits (squash and pumpkins). These three plants, domesticated at different times, were together an important component of Native American agriculture, historically documented by the Seneca and Iroquois, and probably beginning sometime after 1000 AD. All three seeds are planted in the same hole. The maize provides a stalk for the beans to climb on, the beans are nutrient-rich to offset that taken out by the maize, and the squash grows low to the ground to keep weeds down and water from evaporating from the soil in the heat.