by Tamara Scully
While grazing practitioners use a variety of management tools to care for their land and animals, it can be difficult to quantify exactly how much benefit different practices make. Juan Alvez, PhD., of the University of Vermont’s Center for Sustainable Agriculture, has launched a three-year research study designed to see what differences, if any, a variety of farm management practices actually do make.
Quantifying management practices
The basis of grazing systems is grass. The quality and quantity of forage available to the animals is enhanced by a variety of management techniques designed to build soil health. Alvez is studying approximately 20 practices, on three very different grass-based Vermont farms, to determine the impact they have on soil health.
“Some of the practices we are repeating at some farms. The rest are different,” Alvez explained. The three farms — one beef, one sheep and one dairy — will all have regular and biological soil tests performed. Practices being monitored include: tall grazing; interseeding; the addition of soil amendments; and planned grazing. Each farm in the study has a test plot and a control plot, and the researchers are collecting data from these areas in an attempt to quantify how various management practices translate to ecological, as well as economic, benefits on the farm.
An energy assessment in the form of a life-cycle analysis, will be performed on the farms by Eric Garza, professor at UVM. These assessments look at both direct and indirect energy use on the farm, and will calculate each farm’s energy Return on Investment (ROI). The study will allow the farmers to see exactly how much energy is being expended in various activities. ROI impacts a farm’s economic health, Garza explained. Having a life-cycle analysis will allow the farmers the opportunity to implement management practices which can increase their ROI.
“How many inedible calories does it take to make edible calories?” is the question to be answered with the energy life cycle assessment, Garza said. These assessments include indirect — or embodied — calories, which are “the energy that is needed to manufacture and deliver the inputs used on the farm.” The energy needed to make the cleaning fluids used in the milking parlor, for example, is included as a part of the “energy embedded in the things imported onto the farm.”
Measuring soil health
The beef farm was previously an equine hobby farm. All of the acreage was mowed. This manicured lawn left the soil lacking in microbial activity and nutrients, and it was compacted, Alvez said. Fifty acres of land were placed into the control, and another 50 were placed into the grazing study. Physiological, biological and chemical soil analysis are being performed to monitor the impact that managed grazing will have on the soil.
Similar studies are being conducted on the sheep and dairy farms. The biomass of the pastures will be measured by “throwing the dart,” and making an observational assessment of the pasture: insects; plant species; soil texture; soil compaction; and other characteristics. Twenty-five “darts” will be thrown and the pasture assessed on each farm, twice per year, for the three year duration of the study.
“We’ll see, with the management practices that are being applied… if the soils are going to get better,” Alvez said.
The study will measure the unseen activity which occurs in a healthy soil ecosystem. In addition to tracking the soil pH, macro and micro nutrient content and physiological characteristics, the study will “look below-ground” and “re-emphasize the importance of the biological aspects of the soil,” Alvez said.
Topsoil provides food for micro-organisms. Practices which promote topsoil development will lead to increased soil organisms — nematodes, protozoa, amoebas and fungi — which in turn promote increased soil health through aeration, capturing minerals, enabling plants increased access to water and nutrients, and increasing drought resistance.
“We’ve got to start measuring that,” Alvez said of the soil’s food web and ecosystem. “These things are the difference between making money, being profitable, or quitting.”
Energy
Garza’s energy audits measure the “energy-efficiency delivered by using these grass-based operations” to produce food. The audits will help measure the energy cost of various activities associated with producing food on each farm, he said.
The sheep farm transports sheep to some pastures, utilizing fuel. They also make deliveries. These are two areas that the farm may be able to change to increase their ROI. The farm actually uses twice as much energy as the USDA standard for producing meat in the United States. Garza emphasized that the metric used only counts the calorie value of meat sold, not meat produced. Selling all of the meat produced would therefore have an impact on the farm’s data, and potentially decrease the amount of energy the farm uses to raise one calorie of food.
The dairy farm being studied was formally a conventional, confinement dairy with corn-based rations. It now grazes the herd. The change in use of the fields to include grazing animals and pasture will be correlated to changes seen in the soil health. Garza is also hoping to collect data from the dairy before it began its grazing program, to compare the two systems’ life-cycle assessments. The farm today is self-contained, aside from buying in a small amount of silage, Garza said. It is actually now using much less energy to produce one calorie of milk than the average dairy, according to USDA data.
“Human labor is very expensive per unit of work done,” Garza said. “The energy value of the actual hours worked and the energy value of the food the person had to eat to do the work” represents the human energy value needed. Increasing the use of machinery may actually decrease the energy needed, but can increase the farm’s expenses. A pasture system, for example, may decrease the inputs needed on the farm, but may also increase energy, or decrease profitability.
“Profitability is a disincentive to saving energy in general,” Garza said.“ROI is definitely not the whole story.”
The lesson for farms undergoing a life cycle assessment audit is to quantify how energy is being utilized in the system, and see if there are any areas where adjustments can be made to decrease energy needed in relation to the food output. Building soil health through grazing practices would be one way to increase output. Increasing forage output and nutrition will increase animal gain, and therefore food calories, increasing ROI.
“We are measuring some cutting edge technologies… that farmers are using on their farms, to see what works,” Alvez said of the study. During the next several years, pasture walks and workshops will be given to demonstrate the results being seen in the study.
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