1a.Objectives (from AD-416)
The primary objective of the project is to address current knowledge gaps in understanding and managing the nutrient cycles of modern dairy farms. Under this broad research umbrella are five specific objectives: i) to determine the effects of dairy diets and herd management on manure nutrient excretions and nutrient losses to the environment; ii) to determine the effects of manure and crop management practices on nutrients, sediment, and pathogens in surface runoff and other pathways; iii) to determine the effects of season, dairy diet, and field management of manure on gaseous emissions of NH3, N2O, CO2, CH4, and volatile organic compounds; iv) to determine the effects of mechanical application of dairy manure on nutrient uptake and nutritional characteristics of annual and perennial forages; and v) to develop conventional and organic crop management strategies to facilitate the exchange of N, P, and K as manure and feed between neighboring dairy and cash grain farms.

1b.Approach (from AD-416)
Improved management of dairy farms requires successfully managing its nutrient flows, both to maximize nutrient use by animals and crops in order to optimize profit, and to minimize nutrient loss to the environment in order to optimize sustainability. We will investigate most aspects of nutrient cycling throughout the dairy-farm system with a variety of methods and at different scales (replicated field plots, field-scale paired watersheds, feeding trials with replicated pens of heifers, etc.). Some experiments also include non-nutrient elements such as eroded sediment and pathogens. Specific experiments will investigate only one or two nutrient pathways that, taken alone, may seem unrelated. However, our research team has a longer-term goal that will be achieved in future CRIS cycles, which is to integrate information across experiments to more completely describe, quantify, model, and manage the entire dairy-farm nutrient cycle. Achieving this goal will help ensure the existence of sustainable, profitable, environmentally benign dairy farming for coming decades.

3.Progress Report
A range of research activities were carried out as part of this project in support of National Program 206, Manure and Byproduct Utilization. Runoff plots were established and manure treatments were applied to evaluate the effects of dairy cattle corralling on manure nutrient recycling and runoff losses. Manure was collected from dairy heifers fed a diet with or without supplementary phosphorus (P), and effects of applied manure on runoff P were evaluated using simulated rain. Establishment of a paired-watershed field research site to monitor nutrients and pathogens in runoff from different manure/crop management systems was completed and calibration period monitoring is well underway. Compost dairy barn manures were analyzed for nutrients and response of corn to compost dairy barn manure application was measured at eight field locations. A multi-site experiment assessing corn response to dairy and swine manure slurries was completed. On-farm research was continued in China and expanded in Wisconsin and Australia to assess and monitor feed and manure management practices on dairy farms. Bedding, dietary crude protein and forage impacts on ammonia emissions from dairy barns were determined. Most of these activities address the Nutrient Management Component of National Program 206, while some address the Atmospheric Emissions and Pathogens and Pharmaceutically Active Compounds Components.

4.Accomplishments
1. Bedding and diets impact ammonia emissions from dairy barns. Ammonia losses from dairy farms are thought to contribute to dust formation which can imperil human health, and to nitrogen depositions which can damage natural ecosystems. The impacts of bedding, dietary protein and forage on ammonia emissions were measured from a tie-stall dairy barn in central Wisconsin during winter, spring, summer and fall. Ammonia emissions from composted manure solids, newspaper and straw were similar and greater than emissions from pine shavings, but there were no differences in emissions from cows fed corn silage- or alfalfa-silage. During spring, emissions were greater from cows fed high protein than from cows fed low protein diets. Ammonia emissions during spring, summer and fall were two to three times greater than winter emissions. Study results can be used by producers to select beddings and diets that minimize ammonia losses, and also by state regulators in their ammonia emission reporting requirements. This accomplishment addresses the NP206 Atmospheric Emissions Component, Problem Area 1, Understanding the Biological, Chemical, and Physical Mechanisms Affecting Emissions, and Problem Area 2 Emission Factors from Livestock Facilities.

2. Nutrient composition and nitrogen availability of manure from compost dairy barns.

Farmers developed a new method of using deep bedding with sawdust for dairy barns, called compost dairy barns, but little was known about the resulting composition or nutrient supply of the manure. Eight Minnesota compost dairy barns were sampled for manure composition. Manure pH was high, which will promote loss of ammonia when the manure is removed from the barn and spread on the field. Density of the pack beneath the surface layer was uniform, so farmers and advisors will be able to estimate the total weight of manure that will be available to apply. Nitrogen mineralization tests in the laboratory showed that the high carbon content of the manure could reduce nitrogen availability to crops for several weeks after application, a phenomenon that was validated by field observations. These analyses are the first to indicate potential problems with nitrogen supply from compost dairy barn manure, alerting farmers and farm advisors to the importance of manure analysis. These results address the NP206 Nutrient Management Component, Problem Area 4, Farming Systems and Practices for Efficient and Balanced Manure Nutrient Management.

3. Rapid assessment of feed and manure management on dairy farms. Relatively little information is available on feed and manure management under producer conditions, and where improvements in nutrient use can be made to improve profitability and environmental performance of dairy operations. We developed relatively short (2-3h per farm), face-to-face interview and sampling techniques with dairy producers in Wisconsin, Shandong Province, China and Australia to provide accurate ‘snap-shots’ of general feed and manure management practices on diverse dairy farm types. This survey approach is being further developed for use by researchers, extension staff, dairy producers, and nutrient management consultants to monitor overall nutrient use on dairy farms and determine where improvements can be made. This accomplishment addresses the NP206 Nutrient Management Component, Problem Area 1, Animal Feeding and Management, and Problem Area 4, Farming Systems and Practices for Efficient and Balanced Manure Nutrient Management

4. Methods to estimate phosphorus in runoff from surface manure and fertilizer for a quantitative P loss assessment tool.

Non-point source pollution of fresh waters by phosphorus (P) is a concern because it contributes to accelerated eutrophication. Qualitative P Indexes that estimate the risk of field-scale P loss have been developed in the USA and Europe. However, given the state of the science concerning agricultural P transport, a simple tool to quantify annual, field-scale P loss is a realistic goal. We developed new methods to predict annual dissolved P loss in runoff from surface-applied manures and fertilizers and validated the methods with data from 21 published field studies. We incorporated these manure and fertilizer P runoff loss methods into an annual, field-scale P loss quantification tool and validated the tool using independent data from 28 studies. Results demonstrate a P loss quantification tool that does not require greater degrees of complexity or input data than existing P Indexes and can accurately predict P loss across a variety of management and fertilization practices, soil types, climates, and geographic locations. These results support the NP206 Nutrient Management Component, Problem Area 3, Management Tools for Indexing and Evaluating Nutrient Fate and Transport.

5. Field evaluation of recommendations for nitrogen availability of dairy and swine manure.

The value of manure rises in concert with commercial fertilizer prices, yet farmers continue to question the validity of predicted nutrient supply from manure and often over-apply nitrogen (N) fertilizer. We measured the fertilizer N replacement value of fall-applied dairy and swine manure slurries for corn at 13 sites in Minnesota. Manure was either injected directly into the soil or broadcast on the surface and incorporated by tillage equipment afterward. We found that mid-season leaf greenness in manured plots was related to final grain yield, but did not provide a dependable method to predict the additional fertilizer N required to maximize grain yield. On average, estimates of manure N availability based on Minnesota recommendations were most similar to measured values (ratio=1.03 for broadcast-incorporated slurry; 1.06 for direct injection). Recommendations from adjacent states and Manitoba were less similar, ranging from 0.68 to 1.14 for broadcast-incorporated manure and from 0.88 to 1.42 for direct injection. Farmers and farm advisors can use these results to improve nutrient management on farms, but the results also indicate a need for further improvement in estimating manure N availability. This research addressed the NP206 Nutrient Management Component, Problem Area 4, Farming Systems and Practices for Efficient and Balanced Manure Nutrient Management.

6. Soil quality effects of cover crops and dairy manure in silage corn production.

Corn silage is an integral part of most dairy cattle rations, but its production is one of the most demanding cropping systems imposed on our soil resources because erosion, nutrient depletion, and insufficient organic carbon (C) return can degrade soil quality. This research showed that kura or red clover, Italian ryegrass, or winter rye as cover or companion crops improved several chemical, physical, and microbial soil properties and overall soil quality in a no-till silage corn system with dairy manure. Liquid dairy manure alone did not improve soil quality indicators, perhaps because of the low-solids nature of the manure. We found no significant treatment effects on soil organic matter content. However, active carbon (C), a measure of the labile C fraction, was significantly affected by treatments and showed good relationships with physical and microbial soil quality indicators. Overall, use of cover/companion crops and manure appear beneficial for corn silage systems, but it may take more than the four years of this study for some soil quality indicators to fully respond. This research supported the NP206 Nutrient Management Component, Problem Area 4, Farming Systems and Practices for Efficient and Balanced Manure Nutrient Management.

7. Measurement of Ammonia Emissions from Wisconsin Dairy Farms using Laser Technology.

Winter, summer, and autumn NH3 concentration and climatic measurements were made on three dairy farms throughout Wisconsin to calculate emissions using an inverse-dispersion analysis technique. The measured dairies used freestall-type barn systems with nearby sand separators and lagoons for waste management. Emissions were calculated from the whole farm and individually from the barns and waste-management systems. During autumn and summer, whole-farm emissions were significantly greater than winter with about two-thirds of the total emissions from the waste management systems. The average seasonal winter, autumn, and summer ammonia emissions were 1.5, 7.5, and 13.7% of input feed nitrogen emitted as ammonia-nitrogen, respectively. Average annual emissions comparisons between the three farms were similar, with an annual average for all farms of 7.6 ± 1.5%. These winter, summer, autumn, and average annual emissions are considerably smaller than currently-used estimates of dairy emissions and are significantly smaller than emissions from other types of animal feeding operations. These activities support NP206 Action Plan, Component 1, Atmospheric Emissions, Problem Area 2, Emission Factors from Livestock Facilities.

8. Long-Term Research in Wisconsin Shows that Organic Grain Rotations Can Be Productive. During the last half-century, agriculture in the upper Midwest has changed from limited input, integrated grain-livestock systems to primarily high-input specialized livestock or grain systems. This gradual change has spawned debates about sustainability, leading to questions about whether organic production systems can be as productive as high-input conventional systems. Results gathered over 13 years at one site, and eight years at a second site suggest that: (i) organically managed or other similar low-input forage crop systems can yield as much, or more, dry matter as their conventionally managed counterparts with quality sufficient to produce as much milk as the conventional systems; (ii) organically managed and similar low-input corn, soybean, and winter wheat can produce about 90% as well as their conventionally managed counterparts; and (iii) the productivity of corn and soybean averaged over a number of site-years masks a large dichotomy related to the effectiveness of mechanical weed control in the low-input systems. Consequently, biologically diverse, low-input cropping systems can be as productive per unit of land managed as conventional systems, but more research is needed on all aspects of sustainability, and particularly on how to improve weed control in low input row-crops during wet growing seasons. These activities support NP206 Action Plan, Component 2, Nutrient Management, problem Area 4, Farming Systems and Practices for Efficient and Balanced Manure Nutrient Management.

9. Exploratory Studies Show that Dairy Manure Does Not Increase Weed Populations. One reason that cash-grain producers frequently offer for not using manure from neighboring livestock operations is that this practice increases weed populations. Results of an exploratory study suggest that applications of dairy manure did not increase weed populations, nor was it necessary for producers to alter their existing weed control programs. These activities support NP206 Action Plan, Component 2, Nutrient Management, problem Area 4, Farming Systems and Practices for Efficient and Balanced Manure Nutrient Management.

5.Significant Activities that Support Special Target Populations
We continued research on dairy farms having small to medium herd sizes (100 to 200 dairy cows/farm) to understand the impact of biophysical (soils, weather) and socioeconomic factors on nutrient (feed, fertilizer and manure) management practices and the opportunities and challenges to improvements in profitability and environmental impacts through enhanced nutrient use.

6.Technology Transfer

Number of New Commercial Licenses Executed

6

Review Publications
Vadas, P.A., Owens, L.B., Sharpley, A.N. 2008. An empirical model for dissolved phosphorus in runoff from surface-applied fertilizers. Agriculture Ecosystems and the Environment. 127:59-65.