Location: Environmentally Integrated Dairy Management Research
2017 Annual Report
Objectives
Objective 1: Develop land and manure management practices to improve crop and forage productivity, quality, and nutrient use efficiency; and reduce pathogens and losses of nutrients.
Sub-objective 1.A. Conduct multi-scale experiments to investigate biochemical and physical processes controlling snowmelt, snowmelt infiltration and runoff, and nutrient losses from soil and manure.
Sub-objective 1.B. Evaluate nutrient cycling, nitrous oxide and ammonia emissions, and nutrient and pathogen runoff losses with conventional and improved liquid dairy manure management practices for alfalfa production and in a silage corn-rye cover crop system.
Sub-objective 1.C. Determine manure/crop management effects on N, P, and pathogens in runoff from dairy cropping systems.
Sub-objective 1.D. Evaluate effects of alternative manure application methods on alfalfa-grass yield, quality, and silage fermentation characteristics.
Sub-objective 1.E. Determine potential of fall-grown oat to capture nutrients from summer manure or fertilizer applications and produce a late-fall, energy-dense forage crop. Determine potential of spring wheat and barley for fall-forage yield, quality, and nutrient capture from mid-summer manure or fertilizer applications. Evaluate oat mixtures with wheat, triticale or cereal rye (1 planting) for total fall and spring forage yield (2 harvests), as well as nutrient capture.
Objective 2. Develop, improve, calibrate, and validate model routines for nutrient management to assess environmental impacts, nutrient use efficiency, and economics at the farm scale.
Objective 3: Characterize soil biodiversity and manure pathogen dynamics and interactions.
Sub-objective 3.A. Conduct laboratory microcosm experiments to manipulate soil biodiversity and measure die-off rates of dairy manure-borne pathogens.
Sub-objective 3.B. Conduct field studies relating agricultural cultivation practices to soil biodiversity and die-off rates of manure-related pathogens.
Objective 4. Reduce nutrient losses from replacement dairy heifer production through management strategies that target nutrient use efficiency and growth performance.
Sub-objective 4.A. Improve understanding of heifer development and growth, especially effects of genomic testing for residual feed intake (RFI) on nutrient-use efficiency and growth.
Sub-objective 4.B. Determine effect of common management strategies (pen stocking rate, limit feeding, ionophores, diet composition, etc.) on nutrient-use efficiency and growth performance of heifers.
Approach
Improved management of dairy farms requires successfully managing its nutrient flows, both to maximize nutrient use by animals and crops to optimize profit, and to minimize nutrient loss to the environment. We will investigate most aspects of nutrient cycling throughout the dairy-farm system with a variety of methods and at different scales, including replicated field plots, field-scale paired watersheds, feeding trials with replicated pens of heifers, and computer modeling. We will also examine pathogen transport and viability at different points in the dairy farm system. Some experiments will investigate only one or two nutrient or pathogen pathways, while others will be more comprehensive, including, for example, surface runoff, gaseous emission, and plant removal. Computer modeling will investigate the whole-farm system. Our research team also has a longer-term goal, which is to integrate information across experiments to more completely describe, quantify, model, and manage the entire dairy-farm for improved efficiency and sustainability. Achieving this goal will help ensure the existence of profitable, environmentally acceptable dairy farming for coming decades.
Progress Report
A field site with small-scale plots was established to monitor winter hydrology and nutrient loss in runoff from winter applied manure. The first winter of runoff collection was completed and samples were analyzed and data compiled. Lab-scale experiments to investigate the effect of temperature on nutrient release from manure to simulate winter conditions were completed and a manuscript was prepared. Data were compiled from field runoff in Wisconsin and from the literature to assess the ability of the SurPhos model to simulate phosphorus loss in runoff from winter applied manure. A manuscript was published on the results. Simulations identified knowledge gaps on the interaction of snowmelt water with manure and the impact on manure nutrient loss. Lab and field experiments were initiated to investigate these gaps.
The Integrated Farm Systems Model (IFSM) was selected to simulate whole farm nitrogen cycling and use efficiency. However, in-depth investigation of the model soil processes showed it needs substantial improvement. A separate soil model will be used in connection with the barn, animal, and manure storage portion of IFSM. Collaborations with ARS and non-ARS members of the Dairy Agroecosystems Working Group were advanced to detail data of management practices and soil water and nitrogen losses to evaluate the farm model. Simulations of representative dairy farms in California are being corroborated with dairy cooperative consultants and university extension officers. A new routine for IFSM was developed that allows users to specify cow rations. This routine allows the user to by-pass the model’s ration formulation routine and investigate the impact of a specific diet for lactating cattle.
Investigated the validity of quantitative microbial risk assessment (QMRA) compared to epidemiology to determine the human health risk of waterborne pathogens transmitted from dairy farms. Collected data in 2016 and 2017, performed analyses in 2017, and currently working on first of 2 manuscripts. Measured distribution of antibiotic resistance genes (ARGs) in groundwater impacted by dairy manure and human wastewater in Wisconsin. Collected samples in 2016 and 2017. Currently analyzing samples for antibiotics, validating methods for measuring ARGs, and processing samples for metagenomic analyses. Established outgoing agreement with US Geological Survey’s Wisconsin Water Science Center to assist with ARG analyses.
Identified opportunities to optimize farm-scale anaerobic digestion of dairy manure for pathogen removal. Analyzed data and submitted manuscript in 2016. Presented work at scientific conference in 2016 and to the US Dairy Forage Research Center’s stakeholder group in May 2017.
Study assessing the effects of dairy slurry applications on the growth and quality of fall-grown oat forages have been completed, data compiled and summarized, and manuscripts submitted and published. A study was initiated during Fall 2016 to assess spring wheat, spring barley, and oat as late-summer forage crops, assuming an approximate harvest date of 1 November. One year of data collection has been completed, and all laboratory work finished. A second production year of the study will be initiated August 2017. An evaluation of mixtures of wheat, rye, and triticale with oat for fall forage production was initiated during Fall 2016. To date, all harvests have been taken and all laboratory analysis is completed. The study will be conducted a second year with establishment of plots anticipated August 2017.
Experiments with young and gravid dairy heifers attempting to relate a genomic marker for residual feed intake in lactating cows with feed efficiency in growing replacement heifers were conducted. Heifers were placed on high and low nutritional planes within these studies. Feeding trials are completed; data is being summarized for publication. An experiment assessing the effects of overstocking in confinement rearing operations for replacement dairy heifers was initiated. The study has been completed, data summarized and a manuscript summited for publication.
In our investigation on the relationship between microbial diversity and pathogen inactivation, we began our experiments using groundwater from a private well as it is easier to manipulate microbial diversity in groundwater than in soil. The following substantial progress has been made: 1) We completed eight groundwater experiments, each manipulated to have five levels of microbial diversity; 2) Inactivation data were collected on two human pathogens (adenovirus and enterovirus) and MS-2 bacteriophage for each experiment and diversity level; 3) Groundwater water microbial diversity was successfully measured by automated ribosomal intergenic space analysis (ARISA); 4) Using the dilution-to-extinction method we learned a 10-4 dilution is necessary for a 25% reduction in diversity; 5) All samples have been analyzed by high throughput sequencing and data analysis to determine diversity levels by this method is ongoing; 6) We are currently fitting models to the inactivation data to determine inactivation rates and these will be related to the microbial diversity measures.
Accomplishments
1. Optimizing manure anaerobic digestion for pathogen control. Anaerobic digestion of manure is used on dairy farms to produce energy. The process also can destroy zoonotic pathogens that infect both livestock and humans. Digestion is often paired with manure separation on large dairy farms where separated solids are used as cattle bedding. The extent of pathogen destruction in digesters is not well-characterized, and the distribution of pathogens in solid and liquid fractions of separated manure is not known. ARS researchers in Marshfield, Wisconsin studied seven manure digesters with separators and determined that pathogen destruction is suboptimal and highly variable among farms and seasons. Surviving pathogens ultimately end up in the liquid fraction of separated manure, which can result in human exposure during land-application. This research shows livestock producers that they must optimize the performance of their digesters to maximize public health benefits. Fortunately, optimization also is likely to improve biogas yields during digestion, which in turn improves the economic viability of digesters.
2. Commonly used computer models underestimate nitrous oxide from agricultural fields. Computer models are increasingly used to help find ways to reduce greenhouse gas emissions from farms, including nitrous oxide from soil. These models need to be tested and compared to make sure they are reliable. ARS researchers in Madison, Wisconsin tested three models and found that they varied widely in how they simulated soil processes controlling nitrous oxide emissions, including microbial respiration, denitrification, and soil nitrogen availability. In addition, the models underpredicted emissions when measured emissions were high. The research shows that there are limits to how well the models can be used for policy or management recommendations for soil nitrous oxide and that scientists need to work together to improve the models; and it shows what variables need to be measured in field experiments to allow better testing and improvement of models.
3. Study shows magnitude of legacy phosphorus challenges for water quality goals. Watersheds throughout the world have a buildup of phosphorus in agricultural soils and stream and lake sediments that can contribute to eutrophication (over enrichment) of surface waters for many years into the future. The influence of this “legacy” phosphorus on water quality needs to be assessed to form realistic goals for farm practices and policy. ARS researchers in Madison, Wisconsin, along with university collaborators, used computer models to quantify the influence of legacy phosphorus on water quality in the Yahara Watershed of southern Wisconsin. Results show there would need to be 70% less phosphorus in soils and 99% less phosphorus in stream sediments to have 48% less phosphorus reach the Yahara lakes, but even these reductions would not be enough to achieve consistently clear lakes. This study gives policy makers and producers specific information on how much phosphorus in soils and sediments will have to be reduced if desired water quality is to be achieved.
4. Agronomic management is established for fall oat forages. Fall-grown oats is a promising option for dairy producers for harvest as silage or to extend the grazing season. However, farmers need basic agronomic management information for successful production. ARS researchers at Marshfield, Wisconsin examined the effect of seeding rate and oat cultivar on yield, potential for lodging, and cow nutritional value, and the effect of nitrogen fertilizer on yield and cow nutritional value. Increasing fall seeding rates beyond traditional rates for spring oats will not consistently improve yields, and may increase the likelihood of lodging. Differences in nutritional value are determined by the maturity rates of the oat cultivars. Cow nutritional value may decrease slightly with more nitrogen fertilizer, but not enough to offset the advantages of greater yield from more fertilizer. This research gives important information to dairy producers in the Upper Midwest for successful production of fall oats for cattle feed.
5. An oxygen-limiting barrier does not improve round-bale silage nutritional quality during the storage for cattle feed. Baling silage and preserving it by wrapping it in plastic has become popular for forage preservation. However, farmers need basic bale management information for successful storage as feed. ARS researchers at Marshfield, Wisconsin evaluated the effects of minimizing plastic wrap, using a plastic with an oxygen-limiting barrier, and extending storage times on fermentation and cow nutritional value of alfalfa bales. Generally, these different management practices did not have an important impact on bale fermentation and nutritional value. Four layers of plastic is acceptable for bale storage integrity, but plastic with an oxygen barrier does not appear to improve bale quality. This research helps cattle producers minimize their costs and still have successful storage of high quality silage bales.
6. Dairy manure and human wastewater both contaminate groundwater in northeastern Wisconsin. Groundwater quality in the dolomite aquifer in northeast Wisconsin has become a contentious issue as dairy farms and suburban development expand. The aquifer is highly vulnerable because the bedrock is extensively fractured and top soil over the bedrock is often shallow. A key question is if contamination of household wells is from land-applied dairy manure or human septic systems. Measuring microorganisms that are found only in cattle manure or only in human wastewater, ARS scientists in Marshfield, Wisconsin learned that of 131 sampled wells in northeast Wisconsin, 40 wells had evidence of cattle manure contamination, 29 with human wastewater contamination, and 7 wells with both. Although wastes from both cattle and people contribute to aquifer contamination, the worst contamination is the result of dairy manure applied inappropriately on shallow soil above bedrock fractures or before a heavy rainfall event. This important research provides local producers and policy makers with information on what sources of contamination are important to target for improved water quality.
Review Publications
Coblentz, W.K., Akins, M.S., Cavadini, J.S., Jokela, W.E. 2017. Net effects of nitrogen fertilization on the nutritive value and digestibility of oat forages. Journal of Dairy Science. 100:1739-1750.
Veltman, K., Jones, C., Izaurralde, R., Reddy, A., Gaillard, R., Duval, B., Cela, S., Ketterings, Q.M., Rotz, C.A., Salas, W., Vadas, P.A., Jolliet, O. 2017. Comparison of process-based models to quantify nutrient flows and greenhouse gas emissions of milk production. Agriculture, Ecosystems and Environment. 237:31-44.
Motew, M., Chen, X., Booth, E.G., Carpenter, S.R., Pinkas, P., Zipper, S., Loheide, S.P., Donner, S., Vadas, P.A., Kucharik, C. 2017. The influence of legacy P on lake water quality in a Midwestern agricultural watershed. Ecosystems. doi:10.1007/s10021-017-0125-0.
Mulkey, A., Coale, F., Vadas, P.A., Shenk, G., Bhatt, G. 2016. Revised method and outcomes for estimating soil phosphorus losses from agricultural land in the Chesapeake Bay watershed model. Journal of Environmental Quality. doi:10.2134/jeq2016.05.0201.
Vadas, P.A., Good, L., Jokela, W.E., Karthikeyan, K.G., Arriaga, F., Stock, M. 2017. Quantifying the impact of seasonal and short-term manure application decisions on phosphorus loss in surface runoff. Journal of Environmental Quality. doi:10.2134/jeq2016.06.0220.
Coblentz, W.K., Ogden, R.K., Akins, M.S., Chow, E.A. 2016. Storage characteristics, nutritive value, and fermentation characteristics of large-round bales of alfalfa-mixed grass forage wrapped with different layers of stretch film. Professional Animal Scientist. 32:805-815.
Coblentz, W.K., Ogden, R.K., Akins, M.S., Chow, E.A. 2017. Nutritive value and fermentation characteristics of alfalfa-mixed grass forage wrapped with minimal stretch film layers and stored for different lengths of time. Journal of Dairy Science. 100:5293-5304.
Coblentz, W.K., Cavadini, J.S. 2016. Effects of seeding rate on the dry matter yield and nutritive value of fall-oat. Crop, Forage & Turfgrass Management. https://dl.sciencesocieties.org/publications/cftm/articles/2/1/cftm2016.0004.
