PRODUCTION MANAGEMENT 4.1 Production Management Overview Production management deals with how farmers combine PRODUCTION MANAGEMENT 4.2 Crop Residue Management Crop residue management (CRM), which calls for fewer Crop residue management (CRM) systems include reduced tillage or conservation tillage practices such as no-till, ridge-till, and mulch-till as well as the use of cover crops and other conservation practices that provide sufficient residue cover to help protect the soil surface from the erosive effects of wind and water (see box, "Crop Residue Management and Tillage Definitions," p. 156). Why Manage Crop Residue? Historically, crop residues were removed from farm 170 technology. CRM can benefit society through an Reduced Erosion. Tillage systems that leave Crop Residue Management (CRM) is a year-round conservation system that usually involves a reduction in the number of passes over the field with tillage implements and/or in the intensity of tillage operations, including the elimination of plowing (inversion of the surface layer of soil). CRM begins with the selection of crops that produce sufficient quantities of residue to reduce wind and water erosion and may include the use of cover crops after low residue-producing crops. CRM includes all field operations that affect residue amounts, orientation, and distribution throughout the period requiring protection. Site specific residue cover amounts needed are usually expressed in percentage but may also be in pounds. Tillage systems included under CRM are conservation tillage (no-till, ridge-till, and mulch-till) and reduced tillage. Conservation Tillage-Any tillage and planting system that covers 30 percent or more of the soil surface with crop residue, after planting, to reduce soil erosion by water. Where soil erosion by wind is the primary concern, any system that maintains at least 1,000 pounds per acre of flat, small grain residue equivalent on the surface throughout the critical wind erosion period. Two key factors influencing crop residue are 1) the type of crop, which establishes the initial residue amount and its fragility, and 2) the type of tillage operations prior to and including planting. Conservation Tillage Systems include: No-till-The soil is left undisturbed from harvest to planting except for nutrient injection. Planting or drilling is accomplished in a narrow seedbed or slot created by coulters, row cleaners, disk openers, in-row chisels, or roto-tillers. Weed control is accomplished primarily with herbicides. Cultivation may be used for emergency weed control. Ridge-till-The soil is left undisturbed from harvest to planting except for nutrient injection. Planting is completed in a seedbed prepared on ridges with sweeps, disk openers, coulters, or row cleaners. Residue is left on the surface between ridges. Weed control is accomplished with herbicides and/or cultivation. Ridges are rebuilt during cultivation. Mulch-till-The soil is disturbed prior to planting. Tillage tools such as chisels, field cultivators, disks, sweeps, or blades are used. Weed control is accomplished with herbicides and/or cultivation. Reduced Tillage (15-30% residue)-Tillage types that leave 15-30 percent residue cover after planting, or 500-1,000 pounds per acre of small grain residue equivalent throughout the critical wind erosion period. Weed control is accomplished with herbicides and/or cultivation. Conventional Tillage (less than 15% residue)-Tillage types that leave less than 15 percent residue cover after planting, or less than 500 pounds per acre of small grain residue equivalent throughout the critical wind erosion period. Generally includes plowing or other intensive tillage. Weed control is accomplished with herbicides and/or cultivation. Conventional Tillage Systems (as defined in the Cropping Practices Survey): Conventional tillage with moldboard plow-Any tillage system that includes the use of a moldboard plow. Conventional tillage without moldboard plow—Any tillage system that has less than 30 percent remaining residue cover and does not use a moldboard plow. Source: USDA, ERS, based on Bull, 1993, and Conservation Tillage Iinformation Center, 1996. natural rainfall on highly erodible land (14 percent slope) have compared erosion rates among tillage systems. Compared with the moldboard plow, no-till reduces soil erosion by as much as 90 percent and mulch-till and ridge-till by up to 70 percent. Cleaner Surface Runoff. Surface residues help intercept nutrients and chemicals and hold them in place until they are used by the crop or degrade into harmless components (Dick and Daniel, 1987; Helling, 1987; Wagenet, 1987). In addition, the filtering action of increased organic matter in the top layer of soil results in cleaner runoff (by reducing contaminants such as sediment and adsorbed or dissolved chemicals), and thus benefits water quality in lakes and streams (Onstad and Voorhees, 1987; Conservation Technology Information Center or CTIC, 1996). Studies under field conditions indicate that while the quantity of water runoff from no-till fields was variable depending on the frequency and intensity of rainfall, clean-tilled soil surfaces produce substantially more runoff (Edwards, 1995). Runoff from no-till and mulch-till fields averaged about 30 and 40 percent of the amounts from moldboard-plowed fields (Baker and Johnson, 1979; Glenn and Angle, 1987; Hall and others, 1984; Sander and others, 1989). Average herbicide runoff losses from treated fields with no-till and mulch-till systems for all products and all years were about 30 percent of the runoff levels from moldboard-plowed fields (Fawcett and others, 1994). Under normal production conditions, the presence of increased crop residue reduces the volume of contaminants associated with runoff to surface waters by constraining sediment losses and enhancing infiltration (Edwards, 1995; Fawcett, 1987). Higher Soil Moisture and Water Infiltration. Crop residues on the soil surface slow water runoff by acting as tiny dams, reduce surface crust formation, and enhance infiltration (Edwards, 1995). The channels (macropores) created by earthworms and old plant roots, when left intact with no-till, improve infiltration to help reduce or eliminate field runoff. This raises the prospect of increased water infiltration carrying agricultural chemicals into the groundwater in specific situations (more discussion later of groundwater effects). Combined with reduced water evaporation from the top few inches of soil and with improved soil characteristics, the higher level of soil moisture can contribute to higher crop yields in many cropping and climatic situations (CTIC, 1996). However, in some areas, soil moisture levels can also be too high for optimal crop growth or leave soils too cool and wet at planting time, thereby reducing yields. Possible Higher Economic Returns. CRM may result in higher economic returns from increased or stable crop yields and lower input costs. CRM systems usually involve fewer trips over a field, resulting in reduced fuel and labor requirements and lower machinery operating costs. Whether CRM in fact reduces total costs of production for farmers depends on the magnitude of the cost savings from reduced tillage operations relative to the other possible costs affected by CRM practices. For example, there may be increased costs associated with the need for specialized equipment to handle high residue on the soil surface, and increased management, labor, and materials to effectively control pest infestations. Moreover, whether CRM results in higher net returns from farming depends on the effects of CRM practices on yields as well as costs. Farmers continually face tradeoffs between advantages and limitations in choosing the tillage system most appropriate for their conditions. Improved Long-Term Soil Productivity. Less intensive tillage reduces the breakdown of crop residues and the loss of soil organic matter. The less a soil is tilled, the more carbon is sequestered in the soil to build organic matter and maintain long-term productivity. No-till improves soil structure (tilth) by increasing soil particle aggregation (small soil clumps), which facilitates water movement through the soil and enables plants to expend less energy to establish roots. No-till can also help to minimize soil compaction through fewer trips over the field and reduced weight and horsepower requirements (CTIC, 1996). Table 4.2.1-National use of crop residue management practices, 1989-961 1 For tillage system definitions, see box "Crop Residue Management and Tillage Definitions," p. 156. 2 Total area planted does not include newly established permanent pastures, fallow, annual conservation use, and Conservation Reserve Program (CRP) acres. However, it does include newly seeded alfalfa and other rotational forage crops in the year they are planted. Source: USDA, ERS, based on Conservation Technology Information Center (CTIC) data from Crop Residue Management Surveys. Reduced Release of Carbon Gases and Air Pollution. Intensive tillage contributes to the conversion of soil carbon to carbon dioxide, which in the atmosphere can combine with other gases to affect global warming. Increased crop residue and reduced tillage enhance the level of naturally occurring carbon in the soil and contribute to lower carbon dioxide emissions. In addition, CRM requires fewer trips across the field and less horsepower, which reduces fossil fuel emissions. Crop residues reduce wind erosion and the generation of dust-caused air pollution (CTIC, 1996). National and Regional CRM Use In 1996, U.S. farmers practiced conservation tillage on almost 104 million acres, up from 72 million acres in 1989 (table 4.2.1). Conservation tillage now accounts for more than 35 percent of U.S. planted crop acreage (fig. 4.2.1). Most of the growth in conservation tillage since 1989 has come from expanded adoption of no-till, which can leave as much as 70 percent or more of the soil surface covered with crop residues. Use of no-till practices increased as farmers implemented conservation compliance plans from 1990 to 1995 as required under the Food Security Act and subsequent farm legislation. The Corn Belt and Northern Plains, with 51 percent of the Nation's planted cropland, accounted for three-fifths of total conservation tillage acres in 1996 (fig. 4.2.2). These regions, plus the Lake States, Mountain region, and Southern Plains, have substantial acreage with 15-30 percent residue cover which, with improved crop residue management, has the potential to qualify as conservation tillage (which requires 30 percent or more surface residue cover). U.S. crop area planted with no-till tripled to almost 43 million acres between 1989 and 1996, while the area planted with clean tillage systems (less than 15 percent residue cover) declined by about one-fifth. Since 1989, no-till's share of conservation tillage acreage has increased while the share with mulch-till and ridge-till has remained fairly stable (fig. 4.2.1). No-till's share of conservation tilled area is greater in the six eastern regions than elsewhere (fig. 4.2.3). The aftereffects of the 1993 Midwest floods resulted in a slight decline during 1994 in acres planted (percent) with conservation tillage, mostly in mulch tillage, in the Corn Belt and Lake States (fig. 4.2.4). |