Crop Rotation

Crop rotation involves the planting of different kinds of crops, in a time and space sequence, given the differential attributes of the crops, whereby a number of agronomic benefits are obtained. Although crop rotation is an age-old practice, it generally went out of practice in the late 20th century with the widespread introduction of agrochemicals and advanced technologies in agriculture, although some observers advocate a return to crop rotation on ecological grounds. In most countries, including those of the developing world, crop rotation had been a response to the growing population pressure on land resources, allowing lesser and lesser room for leaving the land fallow for a set number of years. Fallowing (leaving cultivated land unseeded and unplowed for one or more growing seasons), practiced since the earliest years of crop cultivation, allowed the soil to recuperate and also break the life cycle of crop pests and diseases. Allowing vegetation to grow on the fallow land allows for the accumulation of organic matter and other kinds of nutrients for the next cropping.

Crop rotation is a complex operation. It has a cultural context and is specific to agricultural systems. It should also be tailored to the social, economic, and environmental attributes of a place. Sorting of the crops grown in a particular area for the purpose of rotation also poses a challenge. Crops should be grouped, for instance, as grass crops or leguminous crops; those with shallow or deep roots; those with dense or light foliage; those with fibrous or large roots; those with allelopathic or nonallelopathic properties; those that need lesser or greater amounts of light, water, nutrients, and space; and those with susceptibility to the same pest or disease.

As chemical fertilizers, herbicides (weed killers), insecticides (pest exterminators), and treatments for plant diseases became more readily available, it became more attractive to use such convenient technologies in place of going through the drudgeries of rotating crops. The honeymoon with high-input farming did not last long. The skyrocketing prices of agricultural inputs (e.g., chemical fertilizers, herbicides, and insecticides) for the past 20-plus years have put crop farmers in a difficult situation. The resistance of some weeds, diseases, and pests to chemicals has posed a serious challenge to their effectiveness. Moreover, the environmental effects of the use of agrochemicals have also been reaching disastrous proportions. Although many farmers have continued to use agrochemicals, unimpressed by the looming environmental threats, there is an urgent need to revert to old and environmentally friendly farming practices, such as organic farming (which relies on crop rotation) and integrated pest management. A complete or partial shift to crop rotation could ensure agricultural sustainability as well as environmental sustainability.

The technological challenges that discourage the return to crop rotation are not limited to the relative ease in the use of artificial inputs. Most farming technologies are fit for monocropping and the application of chemical inputs. A return to crop rotation may involve redesigning of farm machines and implements. Even more intractable in this regard are the government policies and institutional arrangements, which are geared to high-input agriculture.

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