Environmental – Economic Impacts of Management-Intensive Grazing on Dairy Farms
Profitability and lifestyle quality can rise dramatically for dairy farmers who successfully switch from the confined-feeding system to the production system based on management-intensive grazing (MIG). Furthermore, because MIG systems improve profitability without increasing milk production either per farm or per cow, they offer an alternative to the higher production-lower price treadmill that dairy farming has been on for decades. The literature also suggests that adoption of the MIG system allows farmers to better conserve their soil resources. Few practices improve soil quality and protect against soil erosion as well as permanent grass vegetation. However, research in several locations, including the Northeast, has questioned the environmental impact of some MIG systems with regard to their potential losses of nitrogen and phosphorus to ground water.
Such questions about environmental impacts could serve as a major roadblock to acceptance of MIG systems as best management practices (BMPs) by regulatory agencies and thus, a roadblock to the adoption of such systems by more dairy farmers. The project will collect data on the environmental and economic performance of three well-managed farms in central Maryland — two grazing-based and one confined feeding-based farms. The project will use piezometer wells and stream sampling to measure year-around nutrient losses by leaching in two small watersheds on each of the three farms. The project will also focus on the economic impacts of MIG by conducting a cost-returns analysis of each farm.
The results of the project will be communicated to small to medium-sized dairy farmers, through the use of farmer-authored fact sheets and presentations at workshops in Maryland and Pennsylvania. The results will also be presented to the regulators (State Depts. of Agriculture and Depts. of Environment or Natural Resources) and extension agents with the aim of providing sufficient information on the nutrient issues to allow appropriate state programs to be developed for MIG systems. If the environmental findings are favorable, and the outreach efforts successful, the project should substantially contribute to improving the diversity, profitability and environmental impacts of dairy farming in the Northeast.
- Maryland and Pennsylvania nutrient management regulators (state policy makers, state and private nutrient management advisors, extension agents, and conservation district personnel) that learned about the environmental and economic impacts of grazing from this project will plan to promote grazing under certain conditions as a sustainable agricultural practice that will contribute to their state’s nutrient management goals.
Forty of the confinement-feeding dairy farmers in Maryland and Pennsylvania who learned about the environmental and economic impacts of grazing from this project will take steps to learn more or switch to grazing.
In order that there be information on the environmental impacts of grazing to disseminate, it is necessary that the research phase of the project precede the outreach phase. In spring and summer of 2001, we successfully installed some 57 piezometer wells and 36 tension lysimeters in six watershed transects on three dairy farms, two grazing-based and one confined feeding based. In addition, we established ten sampling stations along two streams that bisect two of the grazing watersheds.
The original work plan called for sampling groundwater during the fall 2001 and winter 2002 leaching season. The nitrate and phosphorus contents of these samples were to be determined and the data analyzed to provide information on the environmental impacts of the two dairy farming systems. However, rainfall during summer 2001 through March of 2002 was at a record low and the region had unheard of winter conditions so dry that the water table never rose up to the level of even our deepest piezometers until the fall of 2002. Although we did install several deeper piezometers in Fall 2002 to ensure access to groundwater, the negative water balance for the entire period meant that no meaningful leaching samples could be collected. The two streams being studied also went dry during summer 2002. Therefore, we could not generate the groundwater nutrient loading data that was to be presented at various workshops and meetings originally planned for 2002.
During this time, we collected data from farmer records on nutrient inputs and outputs and made a preliminary nutrient balance analysis for the three farms. We also developed a laboratory digestion method that allows us to examine not only the nitrogen leached as nitrate, but also that leached as dissolved organic nitrogen, a soluble nitrogen form of potentially of major significance that has usually not been investigated in agricultural pollution studies. We also were able to collect and analyze a limited number of stream samples during spring 2002. Fortunately, beginning in early October 2002 rainfall patterns returned to normal or even above normal. As a result the groundwater rose in fall 2002 in the normal manner. We therefore were able to collect samples for October, November and December from both streams and from piezometers in all six watersheds. By the end of the year, we had analyzed the nitrate and phosphorus content in most of these samples, allowing us to schedule a workshop meeting to discuss the environmental impacts measured. We arranged this meeting as a session at the annual Farming for Profit and Stewardship Conference sponsored by Future Harvest CASA and Maryland Cooperative Extension and scheduled for January 2003 where we plan to reach both farmers and regulator and agency people.
Although the environmental results data for the planned workshops were not yet available in 2002, project collaborators held a number of field days, meetings, and pasture walks in which the project, grazing, and its environmental implications were discussed. Stan Fultz, project extension partner organized 11 pasture walks in Frederick and Baltimore Counties, one farm tour to Pennsylvania, one classroom meeting, and 12 individual farmer meetings related to the grazing systems aspects of the project project, reaching a total audience of 306. In addition, David Martin, another project extension partner, discussed grazing, soil, and pasture management in a meeting for 150 equine owners at the Horse World Expo. Bruce Mertz of project partner organization, Future Harvest CASA, also began planning for a series of workshops planned for 2003 to reach both farmers and regulators with the environmental results.
Impacts and Contributions/Outcomes
We did a preliminary analysis of the nitrogen and phosphorus balance on the three farms, using mainly farmer records, but also some of our data on pasture composition. The results suggest that all three farms are running a positive balance in both nutrients – that is they are importing more N and P from all sources than they are exporting in managed outputs (milk, meat, etc.). Therefore, there is probably some accumulation or leaching and runoff losses taking place. The preliminary ratios of inputs to outputs are not too different among the farms (ranging from 1.8:1 to 2.9:1). However, the absolute amount of excess inputs was smaller (45 lb N and 6 lb P per acre) for the Frederick County grazing based farm than for the other two farms (average of 125 lb N and 13 lb P per acre).
Nitrate in the groundwater was below 10 ppm for 95% of the fall 2002 samples from grazed watersheds. The groundwater nitrate data were similar on all six watersheds. The dissolved reactive phosphorus in groundwater was much lower in both Baltimore County grazed watersheds than in the four Frederick County watersheds, suggesting that the difference may be more related to parent rock types (limestone under much of Baltimore County farms) than to management. About one out of five of the groundwater samples from Frederick County (both grazing and confinement farms) had greater than 0.025 ppm dissolved reactive P.
Stream water in both streams on the Baltimore County grazing dairy farm showed little change in N or P from where the stream enters to where it leaves the farm during base flow, but there were changes during storm flow. Winter camping areas and cow access to the stream resulted in increased P and N loads in the samples downstream from these points.
University of Maryland
Glenn Arm, MD
Office Phone: 4105926014
Office Phone: 3013714255
Deerspring Dairy Farm
Maryland Heights, MD
Office Phone: 3013717260