Dr. Paul's Research Perspectives
Transitioning to organic farming
The biological keys to success

By Paul Hepperly, Rita Seidel, and Dave Wilson

Editors' note:
As New Farm Research and Training Manager at The Rodale Institute, Dr. Paul Hepperly has been a regular contributor to NewFarm.org for some time, providing research updates, op-ed pieces, and white papers on topics like carbon sequestration in organic farming systems.

None of those venues do full justice to the range of Paul's experience, however. Paul grew up on a family farm in Illinois and holds a Ph.D. in plant pathology, an M.S. in agronomy and a B.S. in psychology from the University of Illinois at Champaign-Urbana. He has worked for the USDA Agricultural Research Service, in academia, and for a number of private seed companies, including Asgrow, Pioneer, and DeKalb. He has overseen research in Hawaii, Iowa, Puerto Rico, and Chile, and investigated such diverse crops as soybeans, corn, sorghum, sunflowers, ginger, and papaya. He has witnessed the move toward biotech among the traditional plant breeding community and the move toward organics among new wave of upcoming young farmers. Beford coming to the Rodale Institute Paul worked with hill farmers in India to help them overcome problems with ginger root rot in collaboration with Winrock International.

Now we've decided to give Paul his own column, in which he can report on agricultural research from around the world and reflect on its relevance to The Rodale Institute's research program and to the progress of sustainable agriculture more generally in light of his own broad perspective. Enjoy.

February 7, 2005: Maintaining adequate soil nitrogen levels is the first concern of many farmers considering transitioning to organic production. But by growing legume cover crops, soil nitrogen levels can be increased to optimize organic production in short order, even on heavily demanding crops such as corn.

"We have a production system that will produce nitrogen, control erosion, uses energy efficiently, helps control weeds and insects and solves farmer economic problems. It’s free and [it's] called rotation."

- John Vogelsberg, Researcher

Another option for raising soil nitrogen rapidly is the addition of compost and/or manure to supply the rate of nitrogen needed for the target crop. For those that have a hay market, alfalfa/grass hay production is particularly suitable for building soil nitrogen during the transition to organic production.

In The Rodale Institute Farming Systems Trial®, now in its 25th year, we have increased soil nitrogen from 0.29 percent to 0.34 percent by utilizing mixed organic rotations and cover cropping. Control plots managed in a conventional corn-soybean system have seen soil nitrogen fall slightly, from 0.29 percent to 0.28 percent. Normally, as soil organic matter increases under organic management, soil nitrogen limitations are resolved.

In terms of building soil nitrogen, it's hard to beat hairy vetch, which can fix over 200 pounds of nitrogen per acre under favorable conditions. We plant hairy vetch in August after small grain harvest and turn the green manure under in early May before planting corn. We get our nitrogen for the cost of growing and turning under the legume.

In addition, we like to mix oats with hairy vetch. The oats give early fall weed control and reduces the seed cost on the legume. Stands that are a 50-50 mix of oats and hairy vetch can produce the same levels of nitrogen as hairy vetch alone.

Speaking of weeds, two-thirds of farmers we surveyed recently say weeds are their number one production challenge. Our experience supports that view, and we are working with the Pennsylvania State University and the USDA-ARS Sustainable Agriculture Laboratory on this challenge.

In the last two years, we have shown that some corn and soybean varieties tolerate weeds better than others: With the same weed pressure, yield losses ranged from less than 10 percent up to 60 percent. We have also seen that if weeds are less than 1000 pounds per acre in dry matter, significant crop yield losses are minimal even with susceptible soybean varieties.

As with soil nitrogen, cover crops are a key to organic weed management. Using rye as a cover (with up to 8,000 pounds per acre rye dry matter), weeds are greatly reduced in both susceptible and weed tolerant soybean varieties.

Organic systems are not something that can be created over night. McSorley (2002) argues that a central focus of the transition period should be lowering pest populations and achieving a biological balance that will maintain a high level of plant health.

In Maryland, researcher Ray Weil is demonstrating the ability of oil radish and rape to produce a biological fumigation and sub-soiling effect through the generation of natural cyanide and roots powerful enough to fracture the clay hard pan.

Although transitioning to organic may seem fraught with pitfalls, you can see that we have a wide array of effective biological strategies to meet the principal challenges. John Vogelsberg (1987) summarized it this way: “We have a production system that will produce nitrogen, control erosion, uses energy efficiently, helps control weeds and insects and solves farmer economic problems. It’s free and [it's] called rotation.”

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