ISU researcher focuses on organic farming's effect on water quality

AMES, IA - An Iowa State University researcher is looking at the effects of organic farming on water quality.

Kathleen Delate, professor of agronomy and horticulture, has studied organic farming for more than a decade and still has some unanswered questions about the practice.

"We've always wondered what happens under the (organic) plots, in the water, but it's very hard and expensive to monitor," she said.

The study is funded by a grant from the U.S. Department of Agriculture.

Delate has studied organic farming crop rotations since 1998 and has found, in general, yields for organic fields are similar to yields for conventional farming practices, but until now, she has never been able to monitor the quality of water that comes out of an organic system.

Past research has shown that soil carbon, nitrogen and other organic material has increased in the soil when using organic farming methods.

For this water research, 30 plots on the ISU Agronomy Farm in Boone County will each be connected to data-loggers that are continually reading water flow and nutrient analysis, said Delate. The sophisticated data collectors will also read and analyze the amount of sediment running off the fields.

Delate believes the research will show that more water is retained in the organic system and available to crops. She also thinks less water will leave the system, meaning fewer nitrates are leached into the water system.

Some of the plots will be farmed traditionally using a corn/soybean crop rotation. Other plots will be farmed organically using a corn/soybean/oats/alfalfa/alfalfa rotation. And others will be farmed organically with corn/soybean/winter wheat/red clover rotation.

Bids for the project are currently being analyzed and construction on the water-monitoring systems should start later this summer. The first results of the three-year study will be available in 2011.

"Our hypothesis is that the water will be of higher quality in the organic system because organic soils have been shown to have higher organic matter," said Delate. "So there is going to be greater absorption and should be less run off.

"There should also be lower nitrate amounts coming out of the organic system because we're not putting synthetic nitrates into the organic system," she added. "All the nitrates in the soil will come from the legumes like alfalfa, red clover and the compost we are going to use. That's what we think. We'll just have to see what happens."

In the meantime, Delate will be using an organic field near Jefferson to test some of these theories on the correlation between lower nitrogen inputs with longer crop rotations and nitrogen leaching. Although this pre-test will not yield detailed scientific results like the Iowa State site, Delate thinks that researchers will be able learn from results.

"We will have field days out there and show what we are working on," she said. "Iowa farmers are very sophisticated. They know about their nitrogen inputs and soil run-off."

Delate hopes that the results of her research will provide more information for environmentally-conscious producers who are considering organic farming.