Crop Rotations on Organic Farms

sequentially in rotations. In thispublication, we will discuss crop rotationsas key strategies that farmers can use tobuild the soil, manage pests, and increaseyields. Our discussion will be organizedaround the following topics:• A historical perspective. We willdescribe how crop rotations fit into thehistory of farming in America,particularly in the South, and howmodern conventional farming methodshave altered the way some farmerspractice crop rotations.• <strong>Crop</strong> rotations versus continuouscropping. We will summarize theresults of several scientific studies thathave compared the impacts of longandshort-term rotations andcontinuous cropping, or monoculture, onsoil properties. These studies indicatethat using crop rotations can lead todramatic increases in soil fertility, helpto optimize nutrient and water use bycrops, and improve our soil resources.• <strong>Crop</strong> rotations and soil fertility. Wewill describe the use of crop rotations toimprove fertility.• <strong>Crop</strong> rotations and pest management.We will describe the use of croprotations to manage pests, includingdiseases, weeds, and insects.Continuous <strong>Crop</strong>pingIn the South, continuous cropping thatincorporates organic matter is better thanfallow periods for the soil. During fallowperiods, biomass additions are not made tothe soil. However, mineralization of organicmatter in the soil continues during fallowperiods, thus leading to reductions in organicmatter.A HISTORICAL PERSPECTIVEThere was a time in America when the useof long-term crop rotations figuredprominently in every farmer’s plans toboost soil fertility and control crop pestsand diseases. But since the 1950s, farmersincreasingly have replaced crop rotationswith modern practices, such as usingsynthetic fertilizers to supply annual cropnutrients, applying agri-chemicals tocontrol pests and diseases, and selectingimproved crop varieties for increased yields.Many farmers still use crop rotations, but inmuch shorter cycles. For instance,approximately 80 percent of the U.S. corncrop is now grown in two-year rotationswith soybeans or three-year rotations withsoybeans and wheat. These short, two- tothree-year rotations rarely include pastures,cover crops, or green manures. Thesemodern cropping systems have allowedAmerican farmers to benefit fromeconomies of scale by specializing theiroperations and marketing crops in volume.And these systems require fewer pieces ofequipment because the crops grown are lessdiverse.Such modern farming practices have helpedU.S. farmers to produce remarkable cropyields. Nevertheless, the use of intensivecropping for the past 50 years has causedsome negative impacts on ourenvironment, especially on our farm soils.Today, the biggest risks for farmers aredeclining soil quality and increasingenvironmental degradation. As a result,researchers are once again focusing on croprotations as a primary way to attainsustainable crop production, improvedyields, and the economic returns thatsupport a diversified rural economy.Organic Production—<strong>Crop</strong> <strong>Rotations</strong> on Organic Farms 2