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 soil ecology and the farm landscape. Growers considering organic production for commodity crops should 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 tailor soil health and pest management strategies to fit their specific conditions.

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.

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 as the transition period will set the conditions for success. Rotation sequences should be designed to do the following:

• 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

These usually require combinations or rotations of crops that do not harbor the same insects and diseases, fix nitrogen, inhibit weed growth, and enhance the soil. While supplying enough nitrogen is usually a challenge in organic systems, organic flue-cured tobacco crop rotations present a minor departure from these rotation sequences. Because this crop requires relatively low levels of nitrogen early in the season, rotations should be developed that supply the crop with its nitrogen needs without excess, as this can negatively affect leaf quality. The following crop sequences are some examples of strong rotations for organic commodity 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 will result in more nitrogen returned 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.

Wheat–Soybean–Corn

This classic rotation is also utilized by organic farmers. Traditionally, both double-cropped and full-season soybeans are used in the rotation in roughly equal proportion. Some organic farmers are emphasizing more double-cropping for a variety of reasons from economic to agronomic. The main reason is that soybeans planted after wheat usually suffer less pigweed competition. The first flush of pigweed emergence is larger than subsequent flushes of growth and occurs in May. Double-cropped soybeans planted in June have to contend with fewer emerging pigweeds. To successfully double-crop more often, consider alternatives to wheat as a winter crop. Disease build-up can occur in wheat when wheat is grown on a field too frequently. Both barley and canola have proven to be profitable winter crops. Barley is a preferred feed grain for dairies, often commanding prices similar to corn.

Wheat–Corn–High Value Crop

The acreage of organic tobacco, sweetpotato, and other wholesale vegetable crops has continued to increase. Wheat and corn have provided valuable rotations, both economically and for managing pests. Soybeans are sometimes included in this rotation but concerns over inadequate weed management leading to increasing the weed seed bank have limited enthusiasm in some regions.

Tobacco–Summer Cover Crop–Sweetpotato

The relatively high profit margins for organic tobacco and sweetpotato allow for this sequence to use a growing season to plant a summer annual cover crop. Sunn hemp and sorghum-sudangrass are typically grown either as a monoculture or biculture as the summer cover crop. These cover crops have the benefit of breaking up weed and pest cycles while also fixing nitrogen (sunn hemp) and producing abundant residue (sorghum-sudangrass). While this system works for many, caution should be taken when following sweetpotato with a grass crop as wireworm populations can increase. Further discussion on this rotation can be found in chapter 8.

A switch to organic production from conventional agriculture requires a 36-month transition period. That is to say, there must be 36 months between the last application of a prohibited substance and organic certification. Experienced grain farmers can use their skills, knowledge, and experience with conventional crops grains as a base to build new proficiency with crop rotation, cover crops, mechanical weed control, record-keeping for certification, and marketing of organic crops. Most North Carolina farmers can go organic with little capital investment; however, mechanical weed equipment, separate storage facilities, or both may be needed.

It is advisable to begin transitioning to organic with 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 with organic production. Fields with more intense pest problems or soil requirements may require 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 North Carolina and 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. A list of buyers who have expressed interest in buying North Carolina organic grain can be found on the NC State Extension Organic Commodities website.

Acknowledgment of Previous Contributing Authors

Molly Hamilton, Crop Science Extension Assistant, NC State University