NCR SARE Intern, Author at SARE

Tile drainage reduces soil moisture levels for optimal crop growth, but there is concern about nitrate loss from these systems. Because the water quality of regional streams, rivers, and lakes can be negatively impacted by nitrate in drainage, researchers at Iowa State University are studying several practices that can be done to reduce the amount of nitrate in drainage water.

In 2009, Iowa State University graduate student, Laura Christianson, applied for an NCR-SARE Graduate Student Program grant, and was awarded $9,953 to provide information to producers about nitrate reduction technologies, and to provide researchers information about producer acceptance of various nitrate reduction approaches, including an innovative approach using woodchip bioreactors.

“When I started my Ph.D., I was drawn to studying bioreactors because they combined an engineered approach to water quality improvement with a natural treatment system,” said Christianson. “I liked the idea that just by routing drainage water through a trench filled with woodchips, you can create a ‘vacation resort’ environment for denitrifying microbes that convert nitrate in drainage water to nitrogen gas. Of course, the further I got into bioreactors, the more I realized we really needed to put this technology within the context of other drainage water quality improvement strategies like wetlands and cover crops.”

Christianson’s NCR-SARE grant project compared the economic cost efficiencies and ecosystem services among seven nitrate reduction methods (wetlands, controlled drainage, cover crops, crop rotation, fertilizer rate reduction, fertilizer timing modification, and denitrification bioreactors). She used these comparisons to develop an educational program with an associated survey to gage the social acceptance of these seven nitrate reduction methods. To further study the perceived adoption potential of these practices in the context of ecosystem service provisioning, a small discussion group was held with farmers. A hand-out comparing the seven practices was distributed at events.

“Each nitrate reduction strategy provides landowners an additional distinct option for drainage water quality improvement and different strategies or combinations of such will be applicable in different locations,” said Christianson. “While the nitrate management practices were very cost effective and had high interest and compatibility, they offered few additional ecosystem services. Conversely, the practices that had high ecosystem service provisioning generally had lower compatibility (wetlands) or interest (crop rotation).”

The newest in the slate of technologies that Christianson researched and presented were woodchip bioreactors (also known as denitrification bioreactors), which are made by routing drainage water through a buried trench filled with woodchips. Woodchip bioreactors, installed at the edge of agricultural fields, can help remove nitrate in tile-drained water.

According to Christianson, bioreactors are well-suited for buffer strips or grassy areas, which typically means that little land is taken out of production. They are specifically

designed to treat subsurface drainage water that contains high amounts of nitrogen as nitrate and that has relatively little sediment. They work best in drainage systems that have few surface intakes, and are not intended to treat runoff or water collected along terraces. Most current bioreactor designs have been successful at reducing the amount of nitrate in drainage from 30 to 80 acres. Because this is an edge-of-field practice, other conservation practices such as no-till, cover crops, and improved nutrient management can be done in the field, and the bioreactor will treat the remaining nitrate that is lost in drainage.

“I think better understanding of the costs of conservation practices, like bioreactors, helps contribute to sustainable agriculture, but a better understanding of what farmers perceptions are of certain practices is important, too,” said Christianson. “We tried to get at both these things with this project. Bioreactors won’t get us to ‘sustainable agriculture’ by themselves, but they can be a new way to talk about water quality and may provide an option for some individuals.”

Sheep and goat production is a growing enterprise for small and limited resource farmers in the North Central region. While small ruminants (sheep and goats) are adaptable to many different production systems and can be raised with relatively few inputs, they present production challenges. For instance, control of internal parasites, especially gasrointestinal nematodes including Haemonchus contortus (barberpole worm, stomach worm), is a primary concern for many sheep and goat producers and is particularly challenging in humid regions. In Ohio, researchers are examining the use of forage chicory as part of a gastrointestinal nematode parasites control strategy for sheep.

“Sheep farms that utilize managed grazing are both economically profitable and environmentally sustainable,” said Bill Shulaw, professor and Extension Veterinarian and at the College of Veterinary Medicine at Ohio State University. “In our region, perhaps the greatest threat to this production system is gastrointestinal parasites, especially the blood feeding Haemonchus contortus. Loss of productivity associated with parasite infections is usually more costly to the farmer than animal deaths, although mortality attributed to parasite infection can be significant too.”

In 2008, Shulaw, together with Ohio State Extension Educators Rory Lewandowski and Jeff McCutcheon, applied for a NCR-SARE Research and Education grant, and was awarded $137,150 to measure animal performance and the potential of plant secondary metabolites found in forage chicory to reduce the impact of parasite infections in sheep.

“Research reports describing plants with possible activity against internal parasites in sheep and goats have been appearing for several years,” said Shulaw. “Here in the U.S., much of the work has focused on Sericea lespedeza and the role of condensed tannins (CT). However, this plant is not particularly desirable in our region, and other reports, mostly from outside the U.S., have suggested that forage chicory might also be useful.”

As the team began investigating forage chicory as a parasite control strategy, they learned that Dr. Joyce Foster and her colleagues at the USDA’s Agricultural Research Service Appalachian Farming Systems Research Center had conducted research with several varieties of forage chicory studying its nutritional value and palatability for small ruminants. They contacted Foster, and together the team of four had collective expertise in sheep management, management intensive grazing techniques and forage production, internal parasite biology and control, and in forage chicory, including the biochemistry that might be involved. The team worked with farmers John Anderson, of Shreve, OH, Curt Cline of Albany, OH, and Bruce Rickard of Fredericktown, OH.

The two-year, on-farm, research project sought to determine the usefulness of a non-traditional forage, forage chicory (Cichorium intybus L.), in controlling gastrointestinal nematode parasites (GIN) in grazing sheep. A comparison forage, brown mid-rib (BMR) forage sorghum (Sorghum bicolor (L.) Moench.) x sudangrass (Sorghum sudanense Piper) hybrid was used to provide a comparable forage to provide a low, or no, parasite challenge. SARE’s Agricultural Innovations fact sheet, Sustainable Control of Internal Parasites in Small Ruminant Production, provides basic information on each parasite approach and cites resources for training and further information. It’s available online at sare.org/SmallRuminant

“Chicory contains sesquiterpene lactone (SL) and small amounts of condensed tannins, and it has been shown to have negative effects on the survival of adult and larval stages of internal parasites of sheep and farmed deer in research conducted in other countries,” said Shulaw. “Published research suggests that the SL concentration is likely the principal factor affecting parasite numbers although this is still incompletely studied.”

Statistical analysis of the data collected over the two-year period revealed that during the respective grazing periods, lambs grazing the BMR gained slightly more weight than the lambs grazing the chicory, but the fecal egg count (FEC) of the lambs grazing the chicory increased less than those grazing the BMR. Shulaw believes that this suggests that the antiparasitic effect of chicory was attributable to a direct effect on GIN. Given the slightly superior weight gain in the BMR lamb groups, Shulaw thinks there was an antiparasitic effect on the GIN in the lambs grazing chicory, at least with regard to their egg output, and that this was likely due to a direct effect of chicory on the worms (as opposed to merely an effect of improved nutrition for chicory, as has been suggested in other studies).

The team disseminated project results to farmers, students, veterinarians and researchers using face-to-face workshops, web programming, field days, presentations at forage and grazing conferences and publication in professional journals.

“Our project examined just one piece of a very large problem in the sheep and goat industries,” said Shulaw. “Going into it, I don’t think any of us, farmers included, believed that forage chicory would be the ‘silver bullet’ that solved the parasite control problem. But we all learned a great deal about various forages, grazing techniques, and the complexities of internal parasite control. I believe that it is this continual questioning and learning process, coupled with applying what we learn, that contributes to sustainability in agriculture.”

Bill Shulaw’s research team created a multi-page fact sheet that describes basic parasite biology for gastrointestinal worms acquired by sheep and goats on pastures, and provides several strategies for managing internal parasitism. It’s available online.

Author: NCR SARE Intern

Iowa Student Studies Woodchip Bioreactors for Nitrate Reduction in Agricultural Drainage

Researchers Study Forage Chicory for Parasite Reduction in Sheep