Dairy Manure Management Research Articles

Dairy Manure and Plant Nutrient Management Issues Affecting Water Quality and the Dairy Industry

Specific requirements for dairy manure management to protect water quality from nutrient pollution depend on the organization of individual farms. Further, the management requirements and options are different for point (farmstead) and nonpoint (field-applied) sources of pollution from farms. A formal management process can guide decisions about existing crop nutrient utilization potential, provide a framework for tracking nutrients supplied to crops, and identify future requirements for dairy manure management to protect water quality. Farm managers can use the process to plan daily activities, to assess annual nutrient management performance, and to chart future requirements as herd size increases. Agronomic measures of nutrient balance and tracking of inputs and outputs for various farm management units can provide the quantitative basis for management to allocate better manure to fields, to modify dairy rations, or to develop alternatives to on-farm manure application. Changes in agricultural production since World War II have contributed to a shift from land-based dairy production to a reliance on capital factors of production supplied by the dairy industry. Meanwhile, management of dairy manure to meet increasingly stringent water quality protection requirements is still a land-based activity. Involving the dairy industry and off-farm stakeholders as participants in the management process for field, farm, and regional dairy production can be the basis for decision-making to reconcile the sometimes conflicting demands of production and water quality protection.

Components of Dairy Manure Management Systems

Dairy manure management systems should account for the fate of excreted nutrients that may be of environmental concern. Currently, regulatory oversight is directed primarily at the assurance of water quality; N is the most monitored element. Land application of manure at acceptable fertilizer levels to crops produced on the farm by hauling or by pumping flushed manure effluent through irrigation systems is the basis of most systems. Nutrient losses to surface and groundwaters can be avoided, and significant economic value can be obtained from manure as fertilizer if adequate crop production is possible. Dairies with insufficient crop production potential need affordable systems to concentrate manure nutrients, thereby reducing hauling costs and possibly producing a salable product. Precipitation of additional nutrients from flushed manures with sedimented solids may be possible. Composting of separated manure solids offers a possible method to stabilize solids for distribution, but, most often, solids separated from dairy manures are fibrous and low in fertility. Manure solids combined with wastes from other sources may have potential if a marketable product can be produced or if sufficient subsidy is received for processing supplementary wastes. Solutions to odor problems are needed. Energy generated from manure organic matter, via anaerobic digestion, reduces atmospheric emissions of methane and odorous compounds. Use of constructed wetlands or harvesting of photosynthetic biomass from wastewater has the potential to improve water quality, making extensive recycling possible.

Status of Dairy Manure Composting in North America

▪ This paper provides an overview of composting on the dairy farm. It summarizes the motivations, methods, problems and opinions of 50 dairy farmers and commercial composters from 17 states in the U.S. and the province of Quebec. It is intended to serve as a progress report about dairy manure composting, showing why farmers are composting; what it costs them in terms of land, labor and equipment; and how well composting is serving them. This information provides some clues about the future of composting as a dairy manure management practice.

Labor, Equipment and Energy Requirements for Handling Swine and Dairy Manure with an Above-Ground Liquid Manure Storage System

A study was conducted on three dairy and one swine farms to determine the labor, equipment and energy requirements of manure handling from collection through land application of liquid dairy and swine manure management systems using above-ground steel storage. Time-motion studies were conducted on manure scraping and collection at dairy facilities with open lot and free stall enclosed barn arrangements. Slurry agitation and removal activities were also observed using the standard agitation pump systems in the steel storage and either a 12.4 m3 (3,300 gal) liquid tank wagon with injectors or a sprinkler irrigation system. Frequency of manure collection and transfer into storage was dependent upon weather conditions, manure volume and moisture of the manure on the open lot facilities. For the three dairies, manure collection activities were more costly than removal activities with 55 to 77% of the operating costs due to energy and labor. For both collection and removal, labor was the greatest expense. Between 58 to 75% of the total fuel usage of all manure system activities was required for manure removal with agitation requiring more fuel than hauling and land application. Distance to the application site was the most important variable in manure removal and a major influence on both time requirements and costs.

Fertilizer Value of Swine and Dairy Manure from an Above-Ground Liquid Manure Storage System

A three year study was conducted to determine the fertilizer value of liquid swine and dairy manure stored in above-ground steel structures. The magnitude of nitrogen losses from dairy manure stored in above-ground systems was determined. Randomized complete block design agronomic experiments were conducted on experimental corn plots at two swine and two dairy farms in east central Indiana. Manure was injected in the spring at three rates to approximate 84, (75 lb/ac), 168 (150 lb/ac), and 252 kg (225 lb/ac) available N/ha each year. A nitrification inhibitor, nitrapyrin, was added at 1.3 kg/ha (1.2 lb/ac) to another group of manure plots. Corn yields fluctuated due to stressful weather conditions during the study, although in general, yields increased as manure application rates increased for both swine and dairy manure. A greater amount of total N was needed from manure than from commerical fertilizer for crop response due to lower N availability in manure and the normal microbial process of manure decomposition in the soil. Adding the nitrification inhibitor to spring injected dairy manure increased yields but not when applied with swine manure. Soil nutrients showed evidence of P build-up in plots where high manure rates were applied. Total N loss from the two dairy manure management systems during summer collection and storage was 33 and 41%. Nitrogen lost prior to manure collection was 26 to 28% and during storage was 5 and 15% of all total loss.