Chapter 2: Organic Crop Production Systems
Ron Heiniger, Crop Science Extension Specialist, NC State University
Molly Hamilton, Crop Science Extension Assistant, NC State University
Organic production systems are based on management practices that promote and enhance farm biodiversity, biological cycles, and soil biological activity. Organic agriculture strives to minimize use of off-farm inputs and relies on management practices that restore, maintain, and enhance the soil ecology and the farm landscape. Growers considering organic grain crops need to recognize that success will depend on developing a diversified crop management system, including an appropriate rotation plan. Recommendations in this guide were developed to help growers adapt soil health and pest management strategies to their growing conditions.
Components of Organic Production Systems
Table 2-1 lists the key components of an organic production system. The choices made for each component will affect the choices for other components as well as soil fertility and pest management.
Table 2-1. Components of cropping systems.
Harvest and storage
An organic production system begins with selection of the best rotation sequence of production crops and cover crops based on the specific characteristics of the field. This is particularly important in the first few years of an organic production system because the transition period will set the conditions for success. Rotation sequences should be designed to:
- reduce weed pressure by minimizing the amount of weed seed produced and reducing perennial weeds;
- increase the amount of mineralizable nitrogen in the soil;
- reduce the incidence of insect and disease pests by eliminating hosts and interrupting pest life cycles.
This usually requires combinations or rotations of crops that attract or harbor different insects and diseases, fix nitrogen, inhibit weed growth, and enhance the soil. The following crop sequences are recommended for organic grain crop production in North Carolina:
Wheat – Red clover (or other forage legume) – Corn. Wheat and the legume provide continuous ground cover, help break up pest cycles, reduce warm-season weeds through the mowing of clover, and increase available nitrogen. Tilling the clover into the soil makes nitrogen available for the succeeding corn crop. Growing the legume for two seasons rather than one will result in more nitrogen return to the soil and a longer period between corn crops to break pest insect and disease cycles. However, in systems without livestock, the legume cover crop might have little economic value unless it can be cut and sold for hay as an organic forage crop. Cutting for hay will reduce the amount of biomass from residue and may reduce the amount of nitrogen available to subsequent crops.
Wheat – Soybean – Corn. This rotation has many of the same advantages as the above rotation, but the soybean crop can be harvested and marketed. One disadvantage of this rotation is longer soil exposure since soybean is planted after wheat and harvested before corn. Weeds emerging in the soybean crop may be difficult to control, and less nitrogen will be fixed by the soybean crop. However, a cover crop could be incorporated into this rotation to provide ground cover when needed, to expand the rotation beyond two years, or both. A short, two-year rotation will need to be approved by a certification agency.
Farmers who have long-established organic fields usually use a longer rotation of four or five years. A longer crop rotation could rely on one of these sequences:
• Corn – rye cover crop – soybeans – rye or crimson clover cover crop – wheat – cowpea cover crop.
• Corn – wheat – (double cropped) soybeans – crimson clover cover crop – sunflowers or summer cover crop – small grain (oats, barley, triticale).
Legumes or other broadleaf crops should be grown at least two of every five years. A well-developed cropping sequence should result in minimal problems with insects and plant diseases. Weeds are usually the major issue for long-term organic systems, but even weed problems can be managed through suppression by particular cover crops and timely cultivation.
Transitioning to Organic Cropping Systems
A switch to organic production from conventional agriculture requires a 36-month transition period. Experienced grain farmers can use their skills, knowledge, and experience with conventional grains as a base to build new production proficiency with organic crop rotation, cover crops, mechanical weed control, record-keeping for certification, and marketing. Most North Carolina farmers already have rotations that include corn, wheat, and soybeans. Such farms can go organic with little capital investment; however, mechanical weed equipment, separate storage facilities, or both may be needed for organic harvests.
It is advisable to begin transitioning to organic with a relatively small acreage and carefully chosen fields. Fields with low weed, insect, and disease pressures and with relatively good soils give the best chance of success when starting organic production. Fields with more intense pest problems or soil requirements may take more experience with organic production to be successful.
Although crops produced during the transition to organic might be marketed for a premium over conventional crops, return will be less than for certified organic crops. Some grain buyers in the Midwest are looking for nontransgenic (non-GMO) corn and soybeans, which must be used in transitional production. Some livestock producers in North and South Carolina are also looking for nontransgenic grains for feed and are willing to pay a small premium. These markets may be harder to identify than traditional organic markets, but they can provide economic incentives during the transition years required to change from conventional to organic farming. Some of these buyers register with this N.C. State University Web site: www.cropsci.ncsu.edu/organicgrains/marketing/buyers.htm.