Crop rotation is the practice of planting different crops in succession on the same piece of land?
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Crop rotation is defined as a “system of growing different kinds of crops in recurrent succession on the same land” (Martin et al., 1976). Rotating different crops year after year adds various economic and environmental benefits. In addition, crop rotation is helpful in long-term soil and farm management.Crop Rotations in Row Crops
Crop rotation is defined as a “system of growing different kinds of crops in recurrent succession on the same land” (Martin et al., 1976). Rotating different crops year after year adds various economic and environmental benefits. In addition, crop rotation is helpful in long-term soil and farm management. Rotating different crops can break pest cycles and add extra nutrients to the soil. Crop rotations build soil fertility, preserve the environment, control weeds, diseases, and insects, and add to crop and market diversity (Baldwin, 2006). Some examples of crop rotations include: corn-soybean (Glycine max L.)-wheat/red clover (Trifolium pretense L.), corn–soybean, corn–soybean–winter wheat, rice–wheat, and other potential rotations. However, these crop rotations are not universally common, rather they depend on different environmental and soils conditions. In the Midwest United States, corn–soybean is the dominating biannual crop rotation (Plourde et al., 2013), whereas, in Asia, rice–wheat is the dominating rotation (Mishra and Singh, 2012). The rice–wheat crop rotation occupies about 18 million hectare area in Asia, of which 75% are in the Indo-Gangetic Plains of India (10 million ha), Pakistan (2.2 million ha), Bangladesh (0.8 million ha), and Nepal (0.5 million ha) (Mishra and Singh, 2012). Both rice and wheat crops feed about 20% of the world population (Mishra and Singh, 2012). Soybean and corn summer crops are widely grown in rotation with Italian ryegrass (Lolium multiflorum Lam) in the subtropical South American regions of Brazil, Argentina, Uruguay, and Paraguay (Neto et al., 2014). In Europe, planting of wheat after rapeseed (Brassica oleracea L.), and wheat after small-grain cereals is very common (Peyraud et al., 2014). Small-grain cereals, grain and forage maize, rapeseed, and sunflower (Helianthus annus L.) accounted for 75% of crops preceding wheat in 2001 (Peyraud et al., 2014).
The use of long-term diverse rotations helps in improving grain yield as well. Baldwin (2006) documented that the grain producers of the United States believe that the use of 2- and 3-year crop rotations produce higher crop yields compared to those grown as monoculture. In Africa, the sole cropping system, crop rotation, and intercropping of legumes and cereals are the dominant cultural practices, and crop rotation has been indicated as the most superior, followed by monoculture, and lastly the intercropping system. Consequently, rotational cropping involving legumes and cereals were reported to be a more sustainable system for increasing food production in Africa than intercropping (Dakora and Keya, 1997).
Mixed cropping systems are favored because they reduce the risk of crop failure caused by unfavorable rainfall patterns as well as pests and disease pressures. There are various benefits to soil health in a diversified cropping system (Sauerborn et al., 2000). Most notably is the improvement of water use efficiency especially in arid and semiarid areas such as West Asia and North Africa. The latter region covers almost about 1.7 billion ha (Kassam, 1981) and is recognized as dryland with a rainfall range of 100–600 mm year−1 (Dennett, 1987). The effectiveness of crop rotation has been studied in another arid area, Saudi Arabia, where rotations of cereals and alfalfa crops managed with center pivot systems showed an improvement in soil hydrological properties and subsequent yield improvement (Al-Rumikhani, 2002). Another long-term study in Syria conducted by Jones and Singh (2000) showed increase in crop yield of a barley-legume rotation compared to continuous barley. A recent study in Egypt showed the ability of crop rotation in decreasing nematode population in the root zone (Ahlam et al., 2015). Therefore, based on the studies conducted across different parts of the world, it has been demonstrated that rotating crops every other year has various economic and environmental benefits.