Conversion from Corn to Grassland Provides Economic and Environmental Benefits to a Maryland Beef Farm

Beef producers must consider management strategies and technologies for reducing potential adverse environmental effects of their farms while maintaining or improving profit. One choice is between using perennial grassland or corn as the primary crop on the farm for feed production. Perennial grassland production systems are generally regarded as more favorable due to reduced nutrient losses to the environment and potential human health benefits through improvements in meat fatty acid composition. Simulation of an Angus cattle-producing farm of 325 acres in northeastern Maryland illustrated that the conversion of the farm from a corn and permanent pasture system to all perennial grassland with the use of more intensive rotational grazing has provided both environmental and economic benefits. Simulated nitrogen loss through ammonia volatilization was increased 21%, but nitrate leaching was reduced 56%, denitrification loss was reduced 50%, and surface runoff loss of P was reduced 75%. This conversion also increased the annual net return of the farm by $18,800 by eliminating the greater machinery, fuel, seed, fertilizer, and chemical costs incurred in corn production. Introduction Major constraints or challenges to the long-term sustainability of livestock operations are profitability and environmental impact. As the beef industry has adjusted to a more global market, the real price of farm produce has declined relative to most production costs. Thus, farms continue to be driven toward more efficient production to remain profitable. Along with this economic pressure are the growing concerns over the impact of farms on the environment. Governmental guidelines and regulations related to nutrient management are encouraging, and in some cases forcing, producers to consider management changes to meet these concerns. Farm nutrient losses of most concern are N and P. Gaseous emission of N (primarily as ammonia) begins soon after urine and feces are excreted and it continues until that manure is incorporated into soil. Incomplete decomposition through nitrification and denitrification also creates and emits nitrous and nitric oxides into the atmosphere during some manure handling and storage practices and following soil incorporation. These gaseous emissions contribute to environmental problems such as acid rain, over-fertilization of ecosystems, and global warming. Ammonia in the atmosphere also contributes to the formation of very small airborne particles which are a human health concern. Overapplication of N to soil can lead to excessive leaching causing health risks associated with high nitrate levels in groundwater. Runoff losses of P, and sometimes N, contribute to the eutrophication of surface waters which damage aquatic life and increase the processing costs for obtaining potable water. Pasture and cropping practices have an important role in farm management with both economic and environmental implications. Harvested and grazed 19 January 2007 Forage and Grazinglands grassland normally provides a major feed source in beef production. Corn can also be an important feed because of the higher forage yields relative to grassland and the greater energy contents obtained when harvested as either silage or grain. Benoit and Simon (1) found that permanent grassland production resulted in lower nitrate leaching losses than corn silage production. Compared to permanent pastures, annual crops such as corn are prone to nitrate leaching since there is no uptake of residual N from the soil in the fall through early spring period. Furthermore, permanent grassland is associated with the preservation of soil organic matter thus increasing water-holding capacity, improving soil fertility, decreasing soil erosion, and increasing the sequestration of carbon from the atmosphere (4). Studies also indicate that beef produced from pasture may have beneficial consequences for human health due to improvements in meat fatty acid composition (10). There are also disadvantages to grass. Manure applied to grassland cannot be incorporated into the soil, which may increase volatile losses and surface losses of water-soluble nutrients. In pastures, urine and feces are deposited in highly concentrated spots where nutrients are not efficiently recycled in crops and thus are more prone to leaching loss (12). When considering cropping changes, producers and those advising producers must consider the impacts occurring throughout the farm and between the farm and its environment. This process requires the integration of considerable information. Whole-farm simulation provides a tool that can assist in this type of comprehensive assessment by considering all the major components, the most important interactions among these components, and their impacts on farm performance, profitability, and the environment. A simulation study was done to compare the long-term environmental and economic benefits of perennial grasslandand corn-based beef production systems on a farm in the mid-Atlantic region. Specific objectives were to (i) simulate an actual grassland-based Angus beef producing farm in Maryland using a whole-farm model, (ii) verify the model by comparing simulated grassland and beef production data to actual farm records, and (iii) compare simulated long-term nutrient losses and economic performance of this production system to those of a corn-based system previously used on this farm. Farm Production Systems The farm is located in an environmentally sensitive area near the Chesapeake Bay. Many management changes have been made to reduce potential nutrient losses from this farm. The primary change, made in the early 1990s, was the conversion from a corn-based production strategy to all perennial grassland. In the 1970s and 1980s, corn silage and grain produced on the farm provided feed for the herd along with continuously stocked permanent pastures. Now the corn land has been converted to renovated grassland that is rotationally stocked along with the permanent pasture to supply all of the required forage. Since the conversion, the producer has recorded grassland production data, which provides useful information for model calibration and evaluation. The farm consists of 325 acres of grassland on Chester silt loam and Gleneld loam soils. The land is moderately sloping with slopes of 8 to 15%. With the current production system, 110 acres are renovated on about a 10-year cycle and the remainder is in permanent pasture of mostly tall fescue (Table 1). Renovated pastures are seeded in orchard grass or tall fescue interseeded with red clover or alfalfa. The predominant tall fescue cultivar is Kentucky 31. Because of the high proportion of legumes maintained in the pastures, endophyte toxicity has not been a problem. A no-till seeding operation is used to establish pastures at a cost of $20/acre. Up to two thirds of the grassland is harvested in the spring and early summer. About half of this forage is preserved as bale silage with the remainder stored and used as dry hay. Remaining grassland in the spring and summer and all grassland in the fall are rotationally stocked with a portion stockpiled for winter grazing (Fig. 1). 19 January 2007 Forage and Grazinglands Table 1. Description of two production systems simulated on a 325 acre beef cattle farm in northeastern Marylandx. x Farm information obtained through producer interviews and farm records. The herd typically consists of 140 registered pedigree Angus cows and progeny with about 25% of the cows replaced each year (Table 1). Replacement heifers calve in December and cows calve from January to March. Of the 100 stockers maintained on the farm, about 25 are sold each year as breeding bulls with 70 finished at 22 to 24 months of age. Cattle are not subject to implant or ionophore treatments. Most of the feed requirement is met with farm-produced forage, but corn grain is purchased for supplemental energy, primarily during the finishing of cattle. Minerals are also purchased to supplement all cattle. Intensive grassland system Corn and permanent pasture system Land and nitrogen use Permanent grassland area (acre) 215 215 Renovated grassland area (acre) 110 0 Fertilizer applied to grassland (lb N/acre) 20 25 Corn area (acre) 0 110 Fertilizer applied to corn (lb N/acre) 0 120 Spring grazing area (acre) 185 215 Summer grazing area (acre) 285 215 Fall grazing area (acre) 325 215