Crops rotations

Biology and Chemistry of Jerusalem Artichoke Helianthus tuberosus L. 

Four-year rotations established in France in the 1920s alternated Jerusalem artichoke in the first year with oats in the second, clover in the third, and wheat in the fourth. By the time the wheat was grown, no Jerusalem artichoke remained in the fields. The mid-summer harvesting of oats and clover helps to destroy developing Jerusalem artichoke volunteers. This type of rotation effectively clears the ground of Jerusalem artichoke (Shoemaker, 1927). 

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Nonchemical or traditional practices, such as weed seed removal, optimal crop seeding rates, crop selection, enhanced crop competitiveness, crop rotation, and mechanical weed control are all important components of an effective weed management program (458,459). In the context of modern intensive chemical herbicide appHcation, nonchemical practices may even represent an innovative approach to weed management and should receive careful consideration. 

Crop Rotations and Diversification. For thousands of years farmers have known that planting their crops in a new location about every 2 years helped reduce Insect, disease, and weed problems. Indeed, crop rotations are effective in reducing many pest problems and are often highly cost effective (15, 16). Unfortunately for many crops, the trend has been toward abandonment of rotations and increased monocultures. Where rotations are not practiced, certain pests tend to multiply as the crops are cultured on the same land year after year (23). As a result, the density of pest populations increases to levels that necessitate heavy pesticide applications. 

A practice somewhat related to crop rotation is crop diversification or polyculture (36). This approach involves planting selected combinations of crops, like corn and beans. 

Most biological and cultural pest controls return greater profits than pesticides. For example, biological pest controls are reported to return from 30 to 300 per dollar invested in control (16). Various cultural controls like host plant resistance, crop rotations, and tillage, also return 30 to 300 per dollar Invested in pest control (16). 

West, T. O. and Post, W. M. (2002). Soil organic carbon sequestration rates by tillage and crop rotation. A global data analysis. Soil Sci. Soc. Am. J. 66,1930-1946. 

N. Z. Lupwayi, W. A. Rice, and G. W. Clayton, Soil microbial diversity and community structure under wheat as influenced by tillage and crop rotation. Soil Biol. Biochem. 30 1733 (1998). 

Pesticides used on crops grown on the test site in previous seasons may also have an impact on the outcome of a field residue trial. Carryover of prior pesticide applications could contaminate samples in a new trial, complicate the growth of the crop in a trial, or cause interference with procedures in the analytical laboratory. For this reason, an accurate history of what has transpired at the potential test site must be obtained before the trial is actually installed. The protocol should identify any chemicals of concern. If questions arise when the history is obtained, they should be reviewed with the Study Director prior to proceeding with the test site. In most annual crop trials, this will not be a significant issue owing to crop rotations in the normal production practices, because the use of short residual pesticides and different chemical classes is often required for each respective crop in the rotation. However, in many perennial crops (tree, vines, alfalfa, etc.) and monoculture row crops (cotton, sugarcane, etc.), the crop pesticide history will play a significant role in trial site selection. 

A sound crop rotational system is of basic importance to the organic farmer. It reduces the risk of diseases and pests associated with monoculture, gives better control of weeds, spreads the labour requirements more evenly over the year, reduces the financial risk if one crop yields or sells badly and provides more interest for the farmer. For instance, take-all is a disease that cannot even be controlled chemically. Winter crops are more susceptible to take-all than spring sown crops and wheat is more susceptible than barley, so the safest position for winter wheat is immediately after a break crop. 

Olesen, J.E., Rasmussen, I.A. Askegaard, M. (2000) Crop rotations for grain production. Proceedings of the 13th International IFOAM Scientific Conference, Basel, Switzerland, p. 145. 

Elimination of Demand for the Slashing and Burning of Forests through Maintenance of Soil Fertility (e.g., through crop rotation, irrigation). 

Crop rotations are important in rice, especially where weedy/red rice is problematic and difficult to control during rice cropping seasons. In order to suppress weedy rice, nearly all rice in Louisiana is grown either in a 1 1 rotation with soybean or a 1 1 1 rotation where crawfish (Procambarus clarkia) are double-cropped following rice, with soybean produced the following season [34]. In 2012, greater than 70% of Arkansas rice was produced in rotation with soybean, with most of the remaining production in a rice-rice rotation [39]. In California, approximately 70% of rice is produced in a rice-fallow or rice-rice rotation [40],... 

Indian mustard (Brassica juncea Czern L.), tall fescue (Festuca arundinacae), birds foot trefoil (Lotus corniculatus), and kenaf (Hibiscus cannibinus) have been used to reduce soil Se levels near Los Banos, California. Total Se concentrations in soil depths from 0 to 60 cm were lower in all cropped plots than in the bare plots after four years (Banuelos, 2000). The efficiency of Se lost from the soil after four years for each of the four crop rotations was in the range of 17-60% (Banuelos, 2000). The cropped plots with only tall fescue had 25% lower soil Se concentrations after four... 

Describe (where possible) the production system components (e.g. crop or livestock health management practices, soil fertilisation methods, crop rotation designs, livestock feeding and husbandry regimes, crop varieties/livestock breeds used) responsible for differences in food quality and safety between production systems ... 

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