Recent ERS Reports on Crop Residue Management "Conservation Tillage Gaining Ground," AO-232, August 1996 (Carmen Sandretto and Len Bull). This special article discusses recent trends in conservation tillage practice adoption and describes some of the benefits and limitations associated with their use on major field crops. Conservation tillage practices such as no-till, ridge-till, and mulch-till were expected to be used on a record-high 103 million acres in 1996 (more than one-third of U.S. planted cropland), with most of the growth due to rapid expansion in the adoption of no-till which nearly tripled between 1989 and 1995 to almost 41 million acres. Expanded use of no-till has been greater for row crops such as corn and soybeans than for small grains or sorghum. Crop Residue Management and Tillage System Trends, SB-930, August 1996 (Len Bull and Carmen Sandretto). Trends in national and regional use of crop residue management show that conservation tillage use expanded from 72 million acres in 1989 to more than 99 million acres in 1994. Tillage systems use on major field crops is presented for 1988-94 and by surveyed States for 1994. Soil Erosion and Conservation in the United States: An Overview, AIB-718, September 1995 (Richard Magleby, Carmen Sandretto, William Crosswhite, and C. Tim Osborn). This report provides background information on soil use, erosion, and conservation policies and programs; summarizes assessments of economic and environmental effects of erosion; and discusses policies and programs as well as options for their improvement. "Analysis of Pesticide Use by Tillage System in 1990, 1991, and 1992 Corn and Soybeans," AR-32, October 1993 (Len Bull, Herman Delvo, Carmen Sandretto, and Bill Lindamood). This special article examines the relationship between pesticide use and tillage systems in the production of corn and soybeans in 1990, 1991, and 1992. Little difference between tillage systems was observed in the percentage of acres treated or in the number of herbicide treatments. Average pounds of herbicide active ingredients applied did not exhibit a consistent pattern across tillage systems over the three year period. Among tillage systems, about 40-50 percent of the herbicide acre-treatments were combination mixes of more than one active ingredient, but no-till was the exception with about 50-60 percent being combination mixes. Corn insecticide applications were not significantly different between tillage systems, although no-till acreage received lower application amounts for each year. "Water Quality Effects of Crop Residue Management," AR-30, May 1993 (Carmen Sandretto). This special supplement points out that crop residue management in combination with other appropriate management strategies and the proper selection and use of chemicals can play a crucial role in protecting water quality. The movement of agricultural chemicals from the point of application to ground or surface waters depends on a complex set of interactions between a variety of site specific factors ranging from the climate and the hydrologic, geologic, and topographic characteristics of the land surface, and the chemical carriers-sediment, surface runoff, and subsurface drainage water-and the respective properties of the active ingredients of the applied chemicals, such as their adsorption, persistence, solubility, and volatility characteristics. son, J. L. Baker, and M. R. Overcash [eds.] Effects of Conservation Tillage on Groundwater Quality: Nitrates and Pesticides. Lewis Pub., Chelsea, MI, pp. 205-215. Wauchope, R. D.,T. M. Buttler, A. G. Hornsby, P. W. M. Weber, J. B. and R. L. Warren (1993). "Herbicide Behavior in Soils: A Pesticide/Soil Ranking System for Minimizing Ground Water Contamination." Proceedings of the Northeastern Weed Science Society, 47. Weersink, A., M. Walker, C. Swanton and F.E. Shaw (1992). "Costs of Conventional and Conservation Tillage Systems." Journal of Soil and Water Conservation. Vol. 47, No. 4. Young, Douglas L., Tae-Jin Kwon, and Frank L. Young PRODUCTION MANAGEMENT 4.3 Cropping Management Rotating crops can help maintain soil fertility and reduce the wheat-fallow-wheat, while monoculture is the most common otating crops to help maintain soil fertility, reduce soil erosion, and control insects and diseases (by disrupting the life cycle of insect pests, weeds, and plant pathogens) was much more common before the mid-1950s, when farmers increased their reliance on insecticides, herbicides, and fungicides, and commercial fertilizers as a means of sustaining or increasing yields. More recently, public concerns about the hazards of these chemicals in the food chain and in ground and surface water have prompted policy makers, universities, and other private sector decision makers to examine ways to reduce the use of these chemicals in agricultural production. Consequently, farmers are increasingly considering production alternatives, including crop rotation, to reduce adverse environmental consequences. Farmers choose between crop rotation (planting different crops successively in the same field) and monoculture (or continuous cropping) based on agro-climatic and economic factors. This choice, in turn, frequently affects the use of fertilizers and pesticides. The Cropping Practices Survey, which collects a 3-year cropping history, indicates various 176 177 179 cropping patterns and how they affect input use in the production of corn, soybeans, cotton, and wheat-the four major commercial crops (see box, "Cropping Pattern Definitions"). Environmental Benefits of Crop Rotations The potential benefits of crop rotation include Crop rotations improve soil conditions so that in most cases yields of grain crops will increase beyond those achieved with continuous cropping (Heichel, 1987; Power, 1987). Corn following wheat, which is not a Cropping Pattern Definitions The following definitions were applied to 3-year crop sequence data reported in the Cropping Practices Survey to represent a cropping pattern for each sample field. The data were limited to the current year's crop plus the crops planted the previous 2 years on the sample field. Monoculture or continuous same crop-A crop sequence where the same crop is planted for 3 consecutive years. Small grains (wheat, oats, barley, flax, rye, etc.) or other close-grown crops may be planted in the fall as a cover crop. The rotation excludes soybeans double-cropped with winter wheat. Continuous row crops—A crop sequence, excluding continuous same crop, where only row crops (corn, sorghum, soybeans, cotton, peanuts, vegetables, etc.) are planted for 3 consecutive years. Small grains or close-grown crops may be planted in the fall as a cover crop. Mix of row crops and small grains—A crop sequence where some combination of row crops and small grains are planted over the 3-year period. The rotation excludes soybeans double-cropped with winter wheat. Hay, pasture, or other use in rotation—A crop sequence that includes hay, pasture, or other use in lor more previous years. The rotation excludes any of the above rotations and any area that was idle or fallow in one of the previous years. Idle or fallow in rotation-A crop sequence that includes idle, diverted, or fallowed land in 1 or more of the previous years. Double-cropped soybeans—A crop sequence, limited to soybean acreage, where winter wheat was planted the previous fall. legume, produces a greater yield than continuous corn when the same amount of fertilizer is applied (Power, 1987). Yields following legumes are often 10 to 20 percent higher than continuous grain regardless of the amount of fertilizer applied (National Research Council, 1989). Crop rotations can also control insects, diseases, and weeds, particularly those pests that attack plant roots. Crop rotations aid in insect management by replacing a susceptible crop with a non-host crop. Rotating corn with soybeans may reduce soil population of corn rootworm larvae and thereby reduce the need for insecticide treatment. In the southern United States, when peanuts are rotated with cotton and corn, the nematode population drops. If cotton is rotated with corn or grown continuously, then the sting nematode can build up to devastating levels in a few years. Crop rotations can also help control soil erosion. Closely sown field grain crops such as wheat, barley, and oats, as well as most hay and forage crops, provide additional vegetative cover to reduce soil erosion. In addition, these crops also compete with broadleaf weeds and may help control the weed infestation in subsequent crops since they are usually harvested before weeds reach maturity and produce seed. Finally, all rotations promote diversification and can provide an economic buffer against price fluctuations for crops and production inputs. Diversification also helps reduce the vagaries of weather and disease and pest infestations. Cropping Patterns on Land Producing Major Crops Corn. Cropping Practices Survey data (see appendix for a description of the survey) indicate that for most areas of the United States, farmers varied the crops planted from year to year. In the 17 major corn growing States, about 63 percent of the corn acreage in 1995 was in rotation with soybeans or other row crops (table 4.3.1, fig. 4.3.1). Twenty-one percent was in continuous corn. Only 9 percent of corn acreage was in rotation with small grains, hay, or pasture and the remaining 7 percent was idle for at least 1 of the 2 preceding years. Over 1991-95, corn monoculturing appears to have declined slightly, while continuous row cropping has slowly but steadily increased (fig. 4.3.1). Soybeans. Nearly three-fourths of soybean acreage in 14 major producing States in 1995 was reported in rotation with corn or other row crops (fig. 4.3.1, table 4.3.1). Continuous soybeans (monoculture) occurred on only 10 percent of the acreage. Farmers in the Table 4.3.1-Cropping patterns and associated chemical use in major producing States, 19951 Id = Insufficient data. n/a = Not applicable. For States included, see "Cropping Practices Survey" in the appendix. 2 See box, "Cropping Pattern Definitions." Source: USDA, ERS, Cropping Practices Survey data. |