Linking soil quality, plant health, and animal nutrition on dairy farms through energy and nitrogen balance

Linking soil quality, plant health, and animal nutrition on dairy farms through energy and nitrogen balance

Summary

In northeast Ohio, 22 dairies were selected to represent management systems ranging from grazing to confinement. These farms were monitored over the 2001 growing season for soil nutrients, plant nutrients and forage yield, as well as animal health and milk yield. Fertilizer use and feed rations were also noted. Data from May and July 2001 show a strong correlation between soil carbon and nitrogen, with total nitrogen and microbial biomass nitrogen (MBN) positively correlated to total carbon. Pastures had more soil MBN and less nitrate (NO3) than cornfields. Initial results suggest that relatively high nitrogen / low fiber diets tended to produce manure with a higher proportion of large organic matter particles (> 2 mm), relative to intermediate-sized particles (> 53 um – < 2 mm), indicating a more rapid passage through the digestive tract.

Objectives/Performance Targets

1) Identify key linkages between the soil and plants in terms of nutrient and energy balance.

2) Measure the quantity and form of substrate available to microbes in the soil and rumen, in the context of nutrient and energy balance.

3) Collect whole-farm data on nutrient inputs and outputs, to describe the link between nutrient balance, efficiency, and health on dairy farms.

Accomplishments/Milestones

Soil and forage were sampled on 22 dairy farms in late April / early May, late June / early July, and late August / early September. Animal feed, milk, and manure were sampled in late April / early May, late June / early July, late August / early September, and mid-late November. Animal rations, milk production numbers, and body condition score (body fat) were also recorded at these times. Soils were analyzed for total carbon, total nitrogen, NH4, NO3, pH, LTI, P1, K, Ca, Mg; P, K, Ca, Mg, Al, B, Cu, Fe, Mn, Zn, S, particulate organic matter, carbon mineralization, and microbial biomass nitrogen. Plant and mixed feed samples were analyzed for total carbon, total nitrogen, NO3, pH, ADF, NDF, P, K, Ca, Mg, Al, B, Cu, Fe, Mn, Mo, Zn, and S. Corn grain will be assayed for zein content. Cornfields were scouted for insect damage in late June. When results are in for all feed samples from 2001, a subset will be selected for rumen digestibility analysis via in vitro dry matter disappearance. Manure samples were analyzed for total carbon, total nitrogen, pH, NH4, NO3, P, K, Ca, Mg, Al, B, Cu, Fe, Mn, Mo, Na, Zn, and particulate organic matter. Milk was analyzed for milk urea nitrogen, protein, fat, lactose, somatic cell count, and percent solids. At the current rate of progress, remaining samples will be processed in time for complete 2001 results to be presented at seminars scheduled for January, February and March of 2002.

Impacts and Contributions/Outcomes

There has been no impact yet, in the sense that the implications of data have not yet been communicated to farmers. Results are still preliminary, as many samples await analysis. After all 2001 data is analyzed, the challenge remains to convey the information in a concrete context. This will be done by attaching the data generated on each farm to maps of the farm fields, and by presenting seasonal profiles of nutrients on individual farms. The dairy nutritionist who consults on this project has expressed an interest in collaborating on several presentations during winter 2002, when he will present the animal ration and production data, and I will present the soil inputs and outputs, and tie the whole farm system together on the basis of biological nutrient cycling. The goal of these presentations is to generate feedback from farmers and scientists. The missing element of this study is an agricultural economist who can give an objective assessment of these dairy systems. Economic data is as hard to come by as animal health data, and I am still unsure of how to approach this challenge. Perhaps an agricultural economist will become interested in this project as a result of next winters presentations, and will be able to provide farmers with some information of value to them in exchange for some basic economic data. If I am unable to recruit an agricultural economist from Ohio State, I will either hire an independent consultant, or form a collaborative arrangement with an agricultural economist from another university in the North Central region. A veterinarian (who also has an interest in soil and crop quality) heard about the project and visited the Stoller’s farm with me. He is considering visiting all 22 farms next year in consulting capacity. I believe that the insight of an ag economist and a vet are essential to provide a practical context for this data.

Collaborators: