UNIVERSITY PARK, Pa. -- Weeds, manure, slugs, cows and a vegetable oil-powered tractor are all part of a unique study being conducted in Penn State’s College of Agricultural Sciences.
Begun in 2010, the Sustainable Dairy Cropping Systems research project involves researchers from several areas of expertise to examine dairy farm sustainability. It simulates a Pennsylvania dairy farm of 240 acres and 65 lactating cows, including young-stock, by growing crops on 12 acres of Penn State’s Agronomy Research Farm at Rock Springs and using a computer program to model herd management.
Combining previous research conducted on a small scale into crop rotations at a farm-scale, the study takes a holistic approach to look at several components of a dairy farm. Various crops are grown for feed and energy use, yield and feed and forage quality are measured, and milk production for the farm’s dairy cows is simulated with a computer model.
Heather Karsten, associate professor of crop production and ecology and lead director of the project, said the goal is to design and identify management practices that will increase farm sustainability by minimizing off-farm inputs and reducing environmental impacts.
"We are looking at ways to conserve soil, nutrients, biodiversity and energy to design a farm that is productive as well as economically and environmentally sustainable," she said. "By using diverse crop rotations and innovative conservation practices, we think we can promote ecological processes to reduce fertilizer and pesticide use, protect soil and water quality, and sustain farm productivity."
Karsten said dairy is an important part of the agricultural economy, but many farmers are under pressure because of the environmental needs to manage nutrients, protect water quality, and reduce soil erosion and nutrient losses, while seeing to the economic needs of managing a farm.
"Dairy farmers must deal with the rising cost of feed and fuel, as well as unpredictability and instability in the milk price," she said. "A big part of our goal is to figure out how we can help dairy producers reduce their off-farm inputs so they are more profitable."
The project combines disciplines such as agronomy, agricultural and biological engineering, entomology, dairy science and agricultural economics. Contributors include scientists from Penn State and the U.S. Department of Agriculture’s Agricultural Research Service; graduate students in agronomy, soil science, ecology, entomology and agricultural engineering; and undergraduate students in various majors serving as research assistants.
Glenna Malcolm, postdoctoral research associate in plant science, is the project manager.
The feed portion of the project involves two, six-year rotations of grains and forages. Both rotations are managed with no-till. The grain rotation uses a combination of weed management practices to reduce herbicide use in a rotation of alfalfa and orchardgrass, canola, rye, soybeans and corn.
The forage rotation evaluates shallow-disk manure injection as an alternative to surface application in a rotation that includes alfalfa and orchardgrass, corn silage, winter wheat, red clover or hairy vetch, and canola.
In both rotations, legumes are planted for "green manure" -- plants that add nutrients and organic matter to the soil -- and for integrated pest management, while cover crops are used to protect the soil.
Karsten said that the rotations provide several benefits, such as promoting biodiversity. The researchers hope to encourage beneficial insects, such as spiders and bees, and to combat pests such as slugs, which are a major problem in no-till systems.
Another important component of the research is energy. Canola is included in the rotations to produce fuel for a straight-vegetable-oil-powered tractor, which is being evaluated for its performance by New Holland. The canola is pressed for the oil, which is put straight into the tractor with no need to convert it to biodiesel. The leftover canola meal serves as a feed for the farm’s dairy cows.
The animals’ rations are maintained by Virginia Ishler, nutrient management specialist. She enters data based on the field results into a computer program to measure feed intake and milk production.
She noted that her work as manager of the Penn State dairy complex contributes to the model.
"The University cows are my barometer," she said. "When their milk production goes up, the virtual cows’ milk production goes up."
The model consists of two different scenarios that use the two different crop rotations, so Ishler performs each calculation twice. She compares cow performance and feed costs in both scenarios to see if one is more profitable than the other.