|By goGreen | September 22, 2011|
Multiple cropping, simply defined, is the growing of two or more crops on the same field during the same year. When the crops are grown one after another the term “sequential cropping” is applied. If the second or later crops are the result of regrowth of the first crop, then the term “ratoon cropping” is used. Sugar cane (Saccharum spp.), sorghum (Sorghum spp.), and even rice (Oryza sativa L.) can be ratoon cropped. Crops that produce no regrowth, as in the case of most annuals, cannot be ratoon cropped.
When two or more crops are grown simultaneously on the same plot of land the term “intercropping” is appropriate. Such crops may be mixed planted, that is, the plants of different crops are intermingled; or they may be sole (pure stand) planted in alternating rows, that is, the plants of each crop are grown in separate rows or strips (wide rows). When one crop is interplanted with a second crop as the first crop approaches maturity, the practice is termed “relay cropping.” All of these cropping practices come under the general heading of multiple cropping.
All forms of multiple cropping have the potential to utilize the soil more efficiently, resulting in greater production from a given unit of land. This is especially true in tropical or subtropical areas of the world with wet and dry seasons. Where water for irrigation is available, exploitation of the abundant solar energy in the dry season is possible. Double, triple, and even quadruple cropping has dramatically increased food production in some countries–making them exporters instead of importers of food crops. Less dramatic increases can also result from other forms of multicropping. Beans (Phaseolus vulgaris L.), for example, can complete their life cycle in dry periods, if fertilized and relay planted in corn or maize (Zea mays L.) toward the end of the wet season.
The exploding world population continues to place a severe strain on existing land resources and their ability to provide enough food. Any technology that can result in increased food production from present land holdings has great potential for easing hunger around the world. Some researchers consider multiple cropping the most important of today’s agricultural practices. Both high and low technology societies can profit from greater use of multiple cropping.
Multicropping is not a new agricultural technique. Evidence of the practice has been found in Egypt dating back to 300 B.C. The Maya Indians in Central America and the Incas in South America practiced both sequential and intercropping.
SYSTEMS OF MULTIPLE CROPPING
Sequential cropping, to be used most effectively, requires the use of fertilizers, high yielding plant varieties, pest control, high planting rates, mechanization, and, where appropriate, irrigation. Sequential cropping of plants with relatively short growing seasons offers better total annual use of land than does a single crop system. It is particularly important to use the improved, early maturing, high yielding varieties. Unlike traditional varieties, these improved types do not lodge, or fall over to the ground, when heavily fertilized and also produce more grain per unit of fertilizer applied. Pest control, as well as irrigation and fertilizers, allows them to yield more nearly at their full potential.
Mechanization, or the use of appropriate mechanical equipment, allows the farmer to perform promptly all the operations of soil preparation–planting, pest control, and harvesting–so that the next crop in sequence is not delayed and a portion of the growing season wasted. In the United States and other more temperate regions of the world where growing seasons are shorter, notillage planting is widely used. With the use of specially designed equipment and early maturing varieties, crops can be planted in the stubble of a previous crop without any further soil preparation. This ensures a minimum of delay and full use of the available growing season. Leaving the stubble in place also minimizes water and wind erosion and affords protection for the newly emerging seedlings.
The use of day-neutral varieties–those not requiring a specific day length to flower and set seed–allows the farmer to grow them at any time of the year, regardless of latitude, if growing conditions are favorable. The availability of water for irrigation permits full use of the dry season.
Early maturing varieties may also suffer less damage from pests. As a general rule, the most serious crop loss due to weeds occurs during the first third of the life cycle. An exception occurs where late maturing varieties compete better with barnyard grass (Echinochloa crusgalli L. Beauv.). Although crop rotation with different crops will generally result in better pest control, it may be feasible to rotate different varieties of the same crop having different disease and insect resistance and better ability to compete with weeds. Sometimes natural predators of pests (biological control) build up to more effective levels when same crop follows same crop. The buildup of the pests with continuous cropping is perhaps more likely to happen, however, and thus rotation with different crops is preferred.
The principles involved in ratoon cropping, a form of sequential cropping, are different from other types of multiple cropping because of such factors as the presence of a well developed root system, earlier maturity, and the perennial nature of the plant. Although the term may be applied to perennial pasture plants, it is considered more appropriately used with respect to field crops such as sugar cane, sorghum, banana (Musa sapientum, M. caven-dishii), cotton, kodra millet (Paspalum scrobiculatum), pineapple (Ananas comosa), and rice.
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