Introduction to crop rotation in organic agriculture
Crop rotation is a structure of designing how to cycle a parcel of land through various crops, reducing the reliance on chemical fertilizers, herbicides, and pesticides. It is how successful farmers nurtured their land over generations, and remains important for farmers today wanting to feed their local environment with healthy food. A basic principle of crop rotation in organic farming is not to grow the same thing in the same place two years running. Actually, the larger the gap between a crop occupying the same piece of ground the better. In this article we also discuss below topics;
- Why is crop rotation important for organic farming
- What is crop rotation in agriculture
- Organic crop rotation examples
- Role of crop rotation in organic farming
- The principle of crop rotation in agriculture
A step by step guide to crop rotation in organic agriculture
Crop rotation is planting a different crop on a specific piece of land each growing season, is essential in organic crop production because it is such a useful tool in preventing soil diseases, weed problems, insect pests, and for building healthy soils. Plants exude a spectrum of photosynthates into the soil that is unique to each plant species. These root exudates influence the soil microbial biodiversity, which, in turn, supports soil function and plant health. Crop rotations it with the farm’s production system, equipment, labor, and market demand for the farm’s crops. With so many variables to consider, developing a good plan is as much an art as it is a science. Itis important to develop a plan for bed preparation that includes row-spacing considerations for future rotations, as this will increase crop rotation options and reduce labor. Crop rotation is the predetermined sequence of crops that one grows in a certain field.
To grow vegetables organically, it’s important to plan what to grow and when known as crop rotation. Changing where you grow each vegetable from year to year helps keep good soil structure, ensures sufficient nutrients, helps to control weeds, and also prevents a build-up of pests and diseases. Crop rotation in organic agriculture is a system of designing how to cycle a parcel of land through various crops, reducing the reliance on chemical fertilizers, pesticides, and herbicides. It is the practice of planting different types of crops sequentially on the same plot of land to improve soil health, optimize nutrients in the soil, and combat pest and weed pressure. For example, say a farmer planted a field of corn. When the corn harvest is finished, and plant beans, since corn consumes a lot of nitrogen and beans return nitrogen to the soil.A simple rotation might involve 2 or 3 crops, and complex rotations might incorporate a dozen or more.
Typically, producers use cropping systems on their farms that include fields containing different rotations to give a diversity of crops in any given year. The benefits of a well-planned crop rotation include lower disease and insect risk, improved soil structure and fertility, increased biological activity in the soil, and better economic risk management. Other unknown rotation effects can increase the yield of subsequent crops. Organic producers are required under the National Organic Program (NOP) rules to select crop rotations that protect and improve the soil and provide pest and nutrient management. Not only does one need to consider the factors above, but also that rotation required to be tailored to a specific site, as well as to an individual’s skills and equipment availability, time management, and the economics and market for specific crops in an area. Organic farmers are not able to use many of the strategies like those involving synthetic chemicals available to conventional farmers. Though, they still have one of the strongest management tool rotation, which can address a variety of issues. A diverse rotation will lead to fewer insect, disease, and weed problems and, with the inclusion of legumes and perennials, increase fertility and soil health. Rotation diversification is a key strategy to reduce production and financial risk.
Advantages of crop rotation in organic agriculture
Well-designed crop rotation makes land both more productive and environmentally sustainable. It helps organic farmers preserve soil quality and avoid monoculture. Crop rotation improves the financial viability of a farm by increasing productivity whilst reducing chemical input costs. Key advantages of crop rotation are;
1. Improved soil fertility and structure – Crop rotation improves the physical and chemical conditions of soil and improves the overall fertility. Nitrogen-fixing legumes that are soybeans and alfalfa in crop rotations fix atmospheric nitrogen into the soil through root nodules. This nitrogen is then obtainable for subsequent crops. Deep-rooted cover crops can draw up nutrients like phosphorus and potassium from deep in the soil, making these nutrients obtainable for subsequent shallow-rooted cash crops.
2. Disease control – Crop rotation will help to control common root and stem diseases that affect row crops. It is highly effective against diseases whose pathogens have a small host range and require soil or crop residue to overwinter. For such diseases, rotating a non-host crop after a host crop prevents the pathogen from reproducing. The pathogen inoculum, ordinarily preserved in crop debris, does not have the essential conditions for its survival, and the disease spread is controlled. For example, soybean cyst nematode populations could be cut in half by rotating soybean with wheat and corn.
3. Increased soil organic matter – Crop rotation will add more crop residues, green manures, and plant debris to the soil. It also requires less intensive tillage, which means that soil organic matter does not degrade as quickly. Increased soil organic matter improves soil infiltration and water holding capacity, and this enables water to be absorbed into the soil. Also, an increase in soil organic matter improves the overall soil structure and the chemical and biological properties of the soil. To maintain or increase organic matter in the soil, include sod-forming crops like perennial grasses (rye) and legumes (alfalfa). Due to their extensive root system, sod crops in rotation build soil organic matter whether they are used as green manures. Also, include green manure crops to add organic matter and nutrients to the soil.
4. Erosion control – It helps control the erosion of soil from water and wind by improving the soil structure and reducing the amount of soil that is exposed to water and wind. Crop rotation supports reduced or no-till farming, which ensures even better protection against erosion. To prevent soil erosion, contain cover crops in the rotation to help provide continuous soil cover. Then, use a mix of crops and cultural practices that minimizes the amount of time that soil is bare.
5. Crop rotation improves the biodiversity of the soil in the organic agriculture – Through crop rotation, the rooting pattern in the soil and the crop residue is also changed. Then, this improves the biodiversity and the fertility of the soil. The planting of different crops on the same piece of land enables the soil to support several organisms that improve the plant health and fertility of the soil.
6. Increased yield – Crop rotation can help increase crop yield. Corn and soybean that is rotated with another crop yield about 10% more than when the same crop is grown continuously. The increased yield is the effect of all of the individual soil and plant health benefits from crop rotation.
7. Provide pest management – To suppress insect pests, diseases, and weeds include crops in different families to break up pest and disease cycles. If diseases exist in the field, then planting less susceptible crops must be included in the crop rotation. Following a cool-season crop with a warm-season crop allows the grower to alternate tillage thus affecting weed germination.
8. Manage deficient or excess plant nutrients – To manage deficient or excess plant nutrients include a green manure crop in the rotation. Alternate nitrogen-fixing crops (e.g., legumes such as peas, soybeans, alfalfa, clovers) followed by high nitrogen demanding crops such as corn, winter wheat, and vegetables.
Considerations for rotating with cover crops
Species selection will depend on when the cover is planted cool season or warm season. How the cover crop will be terminated must be part of the planning process as well. One creative and inexpensive method to transition conventional ground to organic production is to allow a year 1 cover crop planted with organic seed to go to seed so a second cover crop is grown with little seed cost. The first-year cover crop can be rolled in the fall and will give an excellent mulch for the second year’s cover crop, in addition to providing free seeds. Depending on the goals of the farmer, the 2nd year’s cover crop can be disked, rolled, and even harvested. To qualify as organic, any subsequent cash crops planted into this system will need a full three years from the time of application of the last prohibited substance to the time of harvest for the cash crop (the cash crop can be planted before the full 3 years transition, but should be harvested after the 3-year transitional time frame).
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Crop rotation on organic farms
Organic producers are required under the National Organic Program (NOP) rules to select crop rotations on the farm whether they grow field crops, vegetables, hay, cover crops, and all of the above. The crop rotation under NOP defines the practice of alternating the annual crops grown on a specific field in a planned pattern or sequence in successive crop years so crops of the same species are not grown repeatedly without interruption in the same field. Long-term three to seven-year rotations provide the benefit, but short-term rotations may also be compliant. Though crop rotation is part of the rule and is an integral part of the Organic System Plan (which is considered incomplete without a plan), there is no one right method to create a compliant and successful crop rotation plan. Simply including a fallow period can be a start, but a sustainable rotation will require more diversity over the long run. Organic production systems will have difficulty meeting crop nutrition needs if crops that need high levels of fertility are grown frequently. Heavy feeders (e.g., lettuces, tomatoes, peppers, and corn, etc.) produce more when rotated with light feeders (e.g., carrots, turnips, radishes, and beets, etc.) and nitrogen-fixing legumes.
How to introduce a successful crop rotation in the organic agriculture
Different farms have their management constraints to deal with, general rules for crop rotation are below. In all these things, strike a balance between cash and non-cash crops. Then, this creates a profitable and sustainable crop rotation system.
- Deep-rooted plants must be grown alternately with shallow-rooted crops. This type of rotation combination improves soil structure. For example, the alternate combination of corn with cabbage is a good crop rotation combination for the physical properties of the soil.
- Nitrogen-demanding crops must be grown immediately after nitrogen-fixing plants. For example, soybeans must be followed by corn.
- Plants with high biomass of roots can be grown alternately with plants with low biomass of plant roots. Legumes such as red clover and orchard grass having high root biomass can be grown alternately with low root biomass crops that are soybeans and corn.
- Very fast-growing crops such as buckwheat, sun hemp, and radishes should be grown alternately with slow-growing crops like winter wheat and red clover.
- Slow-growing crops are vulnerable to weeds. Therefore, in a rotation system, they must be grown immediately after weed-suppressing crops such as winter rye.
- Crop rotation can alternate between Autumn and Spring crop plantings; this strategy is effective in reducing weather risk, spreading work pressure, and suppressing weeds.
- Try to cover the soil with crops as much as possible and alternate leafy crops with straw crops to aid in weed suppression.
Planning crop rotations in organic agriculture
Crop rotations are designed to maintain crop and also soil health to ensure long-term sustainability. Though, crop sequences deal with the effects of previous crops on current crop choice. A successful crop rotation encompasses many management components in the organic farming system such as economics, fertility, erosion protection, soil biology, insect, disease, and weed considerations. Realistically, most farms face numerous logistical constraints and end up with cropping plans that do not perfectly achieve these objectives. In these cases, farms should set priorities and design a cropping system to address critical issues first, while achieving acceptable results in other areas, balancing long- and short-term goals. For example, lengthy perennial forage rotations will preserve soil health, but conflict with a dairy herd’s corn silage needs. The following addresses some of the key issues when planning crop rotations.
Organic Matter Contribution – A well-planned rotation of crops and cover crops ensures diverse sources of organic matter, and it is an important strategy for increasing overall organic matter content of the soil. Low carbon-to-nitrogen (C: N) ratio materials, such as legume residues, decompose quickly because they have relatively large amounts of nitrogen, but they contribute very little to the building of humus.
Crop Nutrient Demands – Crop nutrient requirements are very important when planning crop rotation. Organic vegetable growers base their crop rotations on whether various plants in the rotational line-up are light or heavy feeders since crops differ in their ability to extract water and nutrients from the soil. As a general rule heavy-feeding crop must follow a medium-feeder and one or two years of light-feeders or a soil-building cover crop like hairy vetch.
Crop Rooting Depth – Organic farmers base their crop rotations on whether various plants in the rotational line-up are shallow-rooted or deep-rooted. This is particularly important for nitrogen, particularly in lighter soils since it can be leached below the rooting depth of some crops.
Crop Rotation Periods – As previously mentioned, susceptible crops must be rotated at intervals to inhibit the build-up of specific pests. Flexibility can be built into longer rotations. For example, rotation periods of several years can be required to suppress soil-borne pathogens. Longer rotations allow the addition of perennial crops that are grass or legume hay, resulting in healthier soil by building organic matter and improving soil aggregation.
Limitations of crop rotation in the organic agriculture
Certain crops require specific types of equipment, so farmers may have to invest in different types of machinery, which means higher initial costs.
May Require More Knowledge and Skills
Aside from different types of machinery, crop rotation requires a deeper set of skills and knowledge.
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