1a. Objectives (from AD-416)
The overarching objective of our research project is to address current knowledge gaps in understanding and managing the nutrient cycles and pathogen transmission on modern dairy farms. Our specific research objectives are as follows: 1. Determine the effects of dairy cattle diet and dairy herd management (e.g. pasture, confinement, hybrid systems) on manure nutrient excretion, capture, recycling, and loss via gaseous emissions, leaching, and runoff. 2. Determine the effects of dairy manure management practices and cropping systems on crop production, soil properties, and loss of nutrients, sediment, and pathogens (e.g. Cryptosporidium parvum, Salmonella spp., and bovine diarrhea virus) in surface runoff or atmospheric emissions. 3. Determine the effects of timing and rate of dairy manure application on nutrient uptake and nutritional characteristics of fresh and harvested annual and perennial forages. 4. Develop crop management strategies to optimize the exchange of N, P, and K as manure and feed between neighboring dairy and cash grain farms. 5. Develop improved methods for detection and quantification of pathogens in manure, forages, and surface runoff and evaluate effects of management practices on pathogen transport and survival.
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 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 (replicated field plots, field-scale paired watersheds, feeding trials with replicated pens of heifers, etc.). 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. 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 nutrient cycle. Achieving this goal will help ensure the existence of sustainable, profitable, environmentally benign dairy farming for coming decades.
3. Progress Report
A paired-watershed study to evaluate runoff losses of nitrogen (N), phosphorus (P), and pathogens from different manure/tillage/crop management systems is in its fifth year. Findings from the first three years (calibration period and early treatment period) were reported in a recently published journal article. A runoff experiment comparing nutrient loss from corralling areas, pastures, and cropped fields was completed in the spring of 2011. Data are being summarized for presentations and publications. Construction of plots to compare different barnyard surface materials (soil, sand, and bark mulch) was completed in 2010 and cows were placed in them. Greenhouse gas emission data were collected, and leachate and runoff samples are being analyzed for N, P, and sediments. The third year of a field trial to evaluate N availability and losses of ammonia and greenhouse gases from different methods and timing of liquid dairy manure application on corn is in progress. A grazing runoff study funded by a grant from the WI Department of Agriculture was initiated in 2010. Through a cooperative agreement with the University of Wisconsin Platteville, surface runoff from eight small pasture watersheds is being sampled and analyzed for sediment, N, and P to compare different grazing treatments. The data will be used to validate our model to predict P loss in runoff from pastures. Also, as part of the study, four dairy grazing farms in WI are being visited four times annually to collect comprehensive herd, feed, manure management, and milk analysis information and feed and manure samples for lab analysis. This information will be used for future model simulations to estimate P loss in runoff from both grazing and confinement. In partnership with the University of Wisconsin, all summaries of studies evaluating supplementation of phosphorus for growing dairy replacement heifers have been completed and submitted for publication. Plot studies evaluating the capacity of fall-grown oat to capture nutrients from manure applications or other commercial fertilizer sources will be seeded in August 2011 with subsequent harvests continuing through late October. Data evaluating the efficacy of a grass-ley system for opening additional windows for summer manure application on dairy farms, including assessments of voluntary intake of manured forages by dairy heifers, was summarized and published. A pathogen laboratory has been established and was approved by USDA in January 2011 to conduct pathogen research at the Biosafety Level 2+. Researchers developed assays for quantifying over a dozen different dairy manure-borne bacteria, protozoa, and virus pathogens in the environment. Findings from analysis of dairy manure-borne pathogens in runoff from the paired-watershed study were presented at the 2011 General Meeting of the American Society for Microbiology. The laboratory began five studies on the transport of manure-borne pathogens in Midwestern watersheds and groundwater aquifers in collaboration with researchers at the US Geological Survey Wisconsin Water Science Center, Iowa Water Science Center, Iowa State University, and the USEPA in Athens, GA.
Hedtcke, J.L., Posner, J.L., Coblentz, W.K., Hall, J., Walgenbach, R.P., Davidson, J. 2011. Orchardgrass ley for improved manure management in Wisconsin: II. Nutritive value and voluntary intake by dairy heifers. Agronomy Journal. 103:1106-1114.