Conservation Tillage Systems in the Southeast

Principles and Practices of Conservation Tillage Systems

Overview

While each conservation tillage system is designed based on local conditions, there are some general principles and practices born out of research and experience from around the world over the past few decades. All of these are applicable to crop production in the Southeast. They reflect the different agronomic, climatological, ecological, economic and social factors that affect the adoption and performance of conservation tillage systems.

Reduce Tillage

While no-till is preferred to reduce soil compaction, it is not always possible. Soil compaction occurs due to equipment traffic or through natural processes. In-row subsoiling may be required to loosen compacted zones below the planted row [25]. The management objective is to minimize surface disturbance in order to leave crop residues evenly distributed. Use of other conservation practices, such as deep-rooting cover crops, provides tillage benefits through “natural” means and reduces the need to disturb the surface residue with subsoiling [27]. Another method to control soil compaction and minimize the need for tillage is synchronizing operations and machinery to use the same paths through the field, referred to as traffic control [28]. A potential added benefit of controlling traffic using automatic guidance systems is improved crop yields and increased crop profitability [26].

Use Crop Rotations

Crop rotations are planned to enhance cash crop returns, improve soil conditions and fertility, minimize pest pressures and reduce risk. A diverse crop rotation can enhance conservation tillage systems, but diversification must be economical [8]. Bare soil is avoided in conservation tillage systems. Using cover crops or heavy-residue cash crops in crop rotations increases soil-surface coverage and provides significant soil and economic benefits [21, 30]. Sod-based rotations (see Chapter 8) allow for improved integration of livestock into cropping systems and provide another innovative way to enhance crop rotations [13]. Other considerations include the use of legume crops and crops that reduce pest pressures (see chapters 5 and 7).

Maintain Biomass on the Soil Surface

Lal [15] argues that the next step after getting conservation tillage working on a farm is to use cover crops to maximize residue coverage on the soil surface. Cover crops can also be utilized in cropping systems without conservation tillage, but conservation tillage further enhances benefits from retaining the biomass on the soil surface. Derpsch [8] states that “almost all advantages of the no-till system come from the permanent cover of the soil and only a few from not tilling the soil.” Thirty percent residue cover is not the goal but the minimum to reduce erosion. Complete coverage of the soil across the field with as much biomass as can be managed is the best scenario. Selecting heavy-residue cover crops, for example cereal rye, when cash crops produce little to no crop residues is important to garner the maximum benefits from a cover crop and conservation tillage system. Maximizing cover-crop biomass, and therefore residue levels, improves the economic benefits of a conservation tillage system [21].

Manage Equipment

Equipment needs and modifications for use in conservation tillage systems will usually be site-specific and will depend on soil, climate, crop, size of the farm and other factors [28]. Equipment modifications may include (1) row cleaners, down pressure springs, spoke closing wheels, seed firmers and drag chains for planters; and (2) splitter points, polyshields and row cleaners for subsoilers [1]. Additional equipment needs may include the purchase of a no-till grain drill or planter, a subsoiler rig (for example a ripper, Paratill, or terra-till) or a roller/crimper [14]. Additional equipment costs may be offset by selling unused or under-utilized equipment. For example, intensive tillage implements such as a moldboard plow would no longer be used. As the number of trips across the field and the need for powerful equipment declines, under-utilized tractors can be sold.

Manage Carbon

Don Reicosky, an agricultural researcher, has said “true soil conservation is carbon management [29].” Soil organic matter is a key indicator of soil quality, and it is largely composed of organic carbon. Soil organic carbon is a significant determinant of soil biology, aggregation and structural stability. This in turn affects soil fauna and microorganisms, infiltration rates, available water-holding capacity, susceptibility to erosion and bioavailability of plant nutrients. Improving these characteristics improves farm productivity. Managing carbon through conservation tillage systems increases carbon sequestration, resulting in improved soil productivity and farm profitability. A significant step in carbon and soil organic matter management is soil testing. Proper soil testing is critical for transitioning to and properly managing conservation tillage systems [8].

Reduce Off-Site Impacts

Conservation tillage systems help minimize off-site environmental impacts. Conservation tillage systems improve soil quality, especially systems that maximize soil coverage with crop residues. This reduces nutrient leaching, nutrient runoff and pesticide runoff into bodies of water off the farm. Additional complementary practices that further minimize off-site impact include integrated pest management and split applications of fertilizer [9].

Profitability and Sustainability

Farmers seek to maximize profits since profitability is critical to farm viability. For society, sustainability is critical for food, fiber, feed and fuel production needs. Achieving harmony between these two objectives is the goal [24].

Conservation tillage systems can reduce costs for machinery, fuel, labor, herbicides and fertilizer but increase other costs such as for planting and managing cover crops. Whether or not the cost reductions offset increased costs will affect farm profitability [2, 11]. Studies have shown conservation tillage systems with cover crops can reduce input costs for the cash crop, but this may not be enough to offset the increased expense for the cover crop [19]. Crop yields must be enhanced to provide a positive economic benefit. Management is the key! Successful outcomes from conservation tillage systems depend on proper and innovative management, which is addressed in this book.

Another consideration is that conservation tillage systems, especially heavy-residue systems, may stabilize crop yields over time from reduced soil erosion and improved soil productivity. Several studies show these systems can significantly reduce crop losses during drought [2, 11, 30]. Sustainability occurs in the long term, and farmers must have a long-term view. The benefits of conservation tillage systems will increase over time. Although farmers need to respond to short-term shocks, such as changes in crop prices, adhering to long-term conservation goals will maintain the benefits of conservation systems. A decision to implement intensive tillage for short-term gain can undo years of conservation-tillage improvements.

Manage Risks

Most farmers try to minimize risk. There is a certain amount of risk in investing in conservation, primarily due to the lack of certainty about the outcome. This lack of certainty is due to weather variability, time availability, market variability and uncertain profitability of different combinations of practices. Net returns might be less during the transition, though not all farms see a reduction in net returns. A farmer can reduce uncertainty through education, skills development and experience. Research shows that the use of conservation tillage practices may be less risky than conventional intensive-tillage practices [11]. In addition, conservation tillage systems with cover crops, especially legumes, can reduce production risks [12, 16, 17].

Lifelong Learning

It has been said, “No-tillage is not a farming practice; it is a concept of the mind. If you don’t believe in it you will fail [4].” A farmer’s mindset can be a significant obstacle to the adoption and success of conservation tillage systems. To overcome this, farmers and their technical support, such as Extension personnel, agricultural consultants and researchers, will have to become familiar with conservation tillage systems and not just individual conservation practices. They must be familiar with the different aspects of a conservation tillage system to be able to address the issues and problems that arise when transitioning to or managing a system [7].

The most significant hurdle when learning new skills and practices is on-farm implementation. An important strategy is trialing or experimenting with new practices on a small part of the farm. Rolph Derpsch, a well-known conservation tillage consultant in South America, suggests starting by adopting a particular practice or system on 10 percent or less of the farm’s cropped land [8]. Before implementation of a new practice or system, gather as much information as possible. You can find information on local practices from researchers, peers, no-till alliances, conservation agencies and organizations, federal agencies, local agricultural colleges and Cooperative Extension. Successful managers are lifelong learners and keep up with new developments, technologies and information. That is, farmers must get involved [7].

Conservation Programs and Resources

Federal and state governments have conservation programs to help farmers establish conservation practices. NRCS administers a number of conservation programs, including the Environmental Quality Incentives Program and the Conservation Stewardship Program (formerly, the Conservation Security Program; search for NRCS on the web for more information). These programs are voluntary with farmers entering into contracts with NRCS to meet conservation guidelines on their land. In turn, the farmer earns monetary incentives, usually in the form of cost-share assistance, to establish and maintain the practices. These incentives can make conservation practices affordable, for example heavy-residue cover crops, as the farmer transitions and builds experience. They allow the farmer to test particular practices to see if they are suitable to their operation. Taking advantage of these programs can increase the likelihood of farm-wide adoption and can act as a buffer for the farmer if they feel the practices are too risky [3].

Download the table from Chapter 1.

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