Leopold Center Completed Grant Reports Leopold Center for Sustainable Agriculture 1995 High-intensity, year-round rotational grazing James R. Russell Iowa State University, [email protected] Follow this and additional works at: http://lib.dr.iastate.edu/leopold_grantreports Part of the Agricultural Science Commons, Agriculture Commons, Agronomy and Crop Sciences Commons, and the Animal Sciences Commons Recommended Citation Russell, James R., "High-intensity, year-round rotational grazing" (1995). Leopold Center Completed Grant Reports. 77. http://lib.dr.iastate.edu/leopold_grantreports/77 This Article is brought to you for free and open access by the Leopold Center for Sustainable Agriculture at Iowa State University Digital Repository. It has been accepted for inclusion in Leopold Center Completed Grant Reports by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. High-intensity, year-round rotational grazing Abstract Compared to row crops, most forage crops reduce water runoff, therefore limiting soil erosion. Forage systems also require less chemical pest control than row crops. Because legume forage species fix nitrogen in the soil, they seldom require nitrogen fertilization. Despite these advantages, profitability limitations have kept forage use from expanding. Keywords Animal management and forage, Soils and agronomy, Agronomy, Animal Science Disciplines Agricultural Science | Agriculture | Agronomy and Crop Sciences | Animal Sciences This article is available at Iowa State University Digital Repository: http://lib.dr.iastate.edu/leopold_grantreports/77 ISSUE TEAM Leopold Center REPORT LEOPOLD CENTER FOR SUSTAINABLE AGRICULTURE Animal Management High-intensity, year-round rotational grazing Background Prior to the team's establishment, informa­ Compared to row crops, most forage crops tion specific to Iowa was lacking on how reduce water runoff, therefore limiting soil rotational grazing affected plant and animal erosion. Forage systems also require less productivity. Because nutrient deficiencies chemical pest control than row crops. Because may reduce cow rebreeding rates, it was legume forage species fix nitrogen in the soil, necessary to determine the extent to which they seldom require nitrogen fertilization. the stocking rate (of cattle) may be increased Despite these advantages, profitability limita­ in an intensive rotational grazing system tions have kept forage use from expanding. without adversely influencing reproductive efficiency. In addition, because more than Although legume forage species offer higher one-third of the costs of beef cow-calf pro­ yield and nutritive value, their persistence duction in Iowa involves feeding stored feeds, when grazed is uncertain, and reseeding re­ the team has worked on improving the prof­ duces their economic advantages. The Animal itability of such enterprises by extending the Management interdisciplinary research issue grazing season to minimize the amount of team recognized when it formed in 1990 that stored feed needed. One approach they have economic returns from summer pastures could investigated is the grazing of corn-crop resi­ be improved by modifying a pasture's botani­ dues (including systems for extending corn- cal composition, its grazing management, or residue grazing and evaluating its economic both. Rotational grazing increases animal value). In addition, the work has considered production per acre by increasing forage yield the effects of this grazing on soil properties. and harvest efficiency while encouraging the persistence of these valuable forage legumes. Leader: TEAM MEMBERS Mark S. Honeyman, Daryl Strohbehn, Farmers: James R. Russell, Scientists: Outlying Research Animal Science Tom Graham, Department of Dordt College: System Darrell Busby, South­ Grinnell Animal Science, Duane Bajema, John Lawrence, west Area Livestock Ralph Neill, Iowa State Univer­ Agriculture Economics Extension Specialist Corning sity John Olthoff, Agrioul­ Daniel D. Loy, Animal Ann Cowen, Model Conservationists: ture Science Farms Forage Project Robert Dayton, Iowa State University: Kenneth J. Moore, Coordinator, Chariton Soil Gonserva­ Stephen K. Barnhart, Agronomy Alan Teel, County tion Service, Agronomy Daniel G, Morrical, Extension Education Des Moines Michael R. Brasche, Animal Science Director, Osceola James Ranum, Animal Science Ron Orth, Animal E. C. Berry, USDA Soil Conserva­ J. Ronald George, Science National Soil Tilth tion Service, Agronomy Joan G. Hopper, Laboratory West Union J. Arne Hallam, Laboratory Animal Jerry Radke, USDA Ubbo Agena, Economics Resources National Soil Tilth Iowa Depart­ Kenneth H. Holscher, Allen Trenkle, Animal Laboratory ment of Natural Entomology Science Resources 8 Volume 4 (1995) The team also conducted the first evaluation of high-intensity rotational system over the con­ stock-piled forage grazing in Iowa. Because tinuous system were quite robust; they re­ summer and winter feed management plays a mained greater even at considerably lower vital role in determining a cow's ability to rebreeding rates. Grazing in a rotational sys­ rebreed, all these approaches are being consid­ tem at the same stocking rate produced no ered as parts of an overall system. greater amounts of calf per acre, but it did increase rebreeding rates. The increased The Animal Management team's goals are to rebreeding rate from the low-intensity rota­ develop and demonstrate profitable forage- tional stocking system resulted from greater based beef production systems that sustain or amounts of live forage per cow. enhance environmental quality. Toward these goals, the team has evaluated Even at the highest stocking rate, amounts of (1) summer systems that utilize legume for­ available forage per cow exceeded demand in age species and intensive rotational graz­ late May and early June of every year, even ing to optimize long-term animal produc­ though forage was deficient later in the sum­ tion per acre while reducing inputs of mer. Thus, hay production or lead-grazing of fertilizer and herbicides, and younger stock in May and June is necessary for (2) winter systems that minimize costs of us­ optimum forage utilization. Although rota­ ing stored feeds by extending the grazing tional grazing tended to improve alfalfa per­ season via crop residues and/or stock­ sistence compared to continuous grazing, losses piled hay crop forages. of alfalfa from these eight-year-old stands were considerable under the wet conditions in Findings 1990, regardless of grazing system. For this Evaluation of legume forage species: Sum­ reason, an extra pasture is necessary for plac­ mer grazing systems have been evaluated at ing animals during extremely wet weather if two locations. At the Iowa State University alfalfa pastures are grazed. Beef Nutrition Research Center located near Ames, replicated alfalfa-smooth bromegrass­ In addition to evaluating grazing systems in orchardgrass and smooth bromegrass pastures this experiment, the team developed and cali­ were grazed by continuous (0.6 cow-calf units brated a falling plane meter for estimating per acre) or high-intensity rotational (1.0 cow- forage yield from the sward height (see Fig. calf units/ac) stocking systems in 1990 and 1). This instrument has proven useful for 1991. In addition, replicated alfalfa-smooth estimating live forage yield and therefore for bromegrass-orchardgrass pastures were grazed calculating the carrying capacity of a paddock. by a low-intensity rotational (0.6 cow-calf The meter is also being used to relate the sward units/ac) system. When grazed by similar height to forage intake by cows. stocking system, cows grazing pastures con­ taining alfalfa produced 15% greater calf Fig. 1. This plexiglass "sward stick" was weight gains than cows grazing nitrogen-fer- developed as a quick, tilized smooth bromegrass and, therefore, had easy, and relatively a greater profit than cows on smooth brome­ accurate method to grass pastures when compared in economic estimate forage yield models, even if pastures had to be reseeded in summer pastures. Instructions for with alfalfa every five years. Pastures grazed fabricating this tool by a high-intensity rotational system stocked are available from at a rate 66% greater than the continuously team leader Jim stocked pastures had 44% greater calf produc­ Russell. tion. However, the rebreeding rates of cows grazing pastures in a high-intensity rotational system were 12 percentage points less than in continuously stocked pastures. Because of the higher stocking rates, the greater profits of the Leopold Center Progress Reports 9 In evaluating soil compaction caused by cool-season grass pasture. However, the lower grazing, the team determined that compaction rebreeding rates of cows grazing birdsfoot was related to the distance from watering points trefoil is a concern warranting further study. and cow paths and the moisture level of the soil Grazing in a rotational-stocking system allows when cow travel occurred. The presence of a 40% higher stocking rate without an adverse forage increased infiltration considerably. effect on subsequent reproduction. The second evaluation of summer grazing Lower forage allowances associated with rota­ systems, conducted at the McNay Outlying tional stocking at a higher rate reduced calf Research Farm near Chariton from 1991 weight gains, but total calf production was through 1993, compared continuous stocking 26.4% greater than that from continuously (0.5