Organic System Design and Management
The purpose of all of the Kerr Center’s on-farm educational projects is identifying and testing sustainable production systems.
Well-designed organic systems are among the most sustainable. They are resilient due to many factors including higher soil organic levels, greater above- and below-ground biodiversity, and reduced dependence on off-farm inputs.
Organic production is not new at the Kerr Center. For much of its 15-year history, the original 20-acre horticultural farm was certified organic through the Oklahoma Department of Agriculture, Food, and Forestry.
In 2008, the Kerr Center began converting about ten acres of pasture to certified organic status. This Cannon Horticulture site is the main demonstration and research area, including about two acres under organic management. The site was certified organic in 2011.
The site features a long-term soil-building rotation based on cover crops, green manures, and modest inputs of compost. There is a greenhouse and a compost area, with two additional hoophouses built in 2011.
Recycling nutrients and building up the soil through natural means has been the goal of many projects over the years. The staff has experimented with cover crops, compost, and crop rotations to build soil fertility. These are old techniques that are often undervalued, yet they work extremely well.
Cover crops can prevent soil erosion, increase organic matter (which in turn enhances biological activity in the soil), and improve soil structure so that water is more available to crops. Leguminous cover crops, such as purple hull peas or crimson clover, can also add nitrogen to the soil. Key elements in the Kerr Center’s organic system design are as follows:
Rotation Plan: The overall strategy of using summer cover crops on a significant portion of the acreage has been very successful in sustainable soil management and weed suppression. From 2008-2010, the Cannon Horticulture Project featured three half-acre plots in rotation, with a fourth half-acre plot used for testing equipment and other purposes. In 2011, that changed to a 4-field system, making all four plots part of a single planned rotation.
A four-field rotation is adequate to control a wide range of crop pests and diseases. Crop diversity and detailed mapping allow the rotation of crop plantings within fields also, effectively creating an eight-year rotation, which is useful in controlling some especially persistent diseases.
In the following diagram, “summer crops” refers to tomatoes, okra, corn, sweet potatoes, etc., that can be planted in late spring and early summer. “Fall crops” refers both to crops that require hotter planting weather, like peanuts and southern peas, and crops like squash and pumpkins that are planted late (after July 1st) for fall harvest.
Segregating crops into these two groups ensures that timing of tillage and mowing operations varies over time on every plot. This aids in long-term weed management. The current plan does not include early spring-planted crops due to past difficulties in working these fields after normally wet winter/early spring weather.
Growing mulch on-farm: This reduces weed introductions and possible pesticide contamination, while working to recycle nutrients on-project. The mulches will be grown primarily on the four fields and also in buffer zones.
Beneficial habitat and trap crops: Additional efforts will be made to incorporate these more efficiently into the cropping plan, so that they double as cover and smother crops as well. In addition, native pollinator habitat plantings are being made, with help from a Conservation Innovation Grant from the USDA Natiural Resource Conservation Service (NRCS), and in partnership with the Xerces Society.
On-farm fertility inputs: 2010 showed great progress in making compost, compost teas, biochar, and vegetation-based foliar fertilizers. Compost and biochar made from on-ranch resources are preferable to industrial chicken litter. (Biochar is a term applied to any organic material or “biomass” that has been burned or charred with limited oxygen, as is done when making commercial charcoal for fuel. Biochar has promise as a soil amendment and a means of stabilizing and sequestering carbon.)
Contact: George Kuepper
Educational Resources
An increasing number of farmers and gardeners in Oklahoma and the South are growing crops organically and need information. Kerr Center offers farmers and gardeners a variety of resources and publications on organic production and transitioning to organic production, certification, and processing. A sampling of these includes:
Organic Resources Page
(production, transition from conventional to organic, certification, marketing).
Kerr Center's Organic Publications
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