Get to know retaiN

retain

Post submitted by Jamie Benning, Water Quality Program Manager for Iowa State University Extension & Outreach

The retaiN project was inspired by experiences of Tim Smith, an Eagle Grove, Iowa farmer.  Smith participated in tile monitoring and found levels of nitrates in his tile to be higher than he preferred even though he had been implementing conservation practices for many years.  The tile monitoring data moved him to action, leading him to increase his on-farm testing and implement conservation practices that reduce nitrate loss.  Conservation Districts of Iowa and the Iowa State University Extension and Outreach Water program led the effort to develop an easy to use nitrate testing kit to encourage other farmers to gather their own nitrate data to support decision making related to nitrogen management and reduction of nitrate loss.

Through support and partnership from the State Soil Conservation Committee, Iowa Learning Farms, Iowa Department of Agriculture and Land Stewardship, Division of Soil Conservation and Water Quality, the retaiN nitrate testing kits were developed.  The kits include a bottle of 25 Hach nitrate and nitrite testing strips and a booklet with nitrate monitoring instructions, nitrogen practice information and data log section all in a shippable box.  The Hach test strips are simple and easy to use and provide the farmer with a concentration reading in 60 seconds.

During the pilot phase of the project, 500 kits were distributed to established watershed projects, agriculture organizations and ISUEO field agronomists and engineers.  Watershed coordinators and ISUEO specialists distributed the kits to individual farmers and provided follow-up calls and encouragement to sample throughout the 2015 growing season.  Farmers were encouraged to sample tile outlets on their farms bi-weekly, or more frequently as time allowed.  After the pilot phase, a survey of farmers and landowners and watershed coordinators and ISUEO specialists was conducted. The evaluation feedback from has been overwhelmingly positive.  One farmer wrote, “The kit is quick, very simple to use and gives you immediate results. It helps me determine if I am losing any nitrogen”.

After the pilot phase, modifications to the kit materials were made based on survey feedback and kit distribution by watershed coordinators and extension field specialists and county specialists continued.  Additionally, a partnership with Iowa Corn Growers Association (ICGA) was developed.  The Iowa Corn Growers distributed kits to farmers during their Crop Fairs, Soil Health Partnership events, and watershed education and outreach events across the state.   To date, over 1500 retaiN kits have been distributed.  Conducting on-farm tile monitoring through the retaiN project has been a catalyst for farmers and landowners to gather baseline nitrate data for their farm, implement nitrate reduction practices, prioritize changes to their nitrogen management practices and explore additional monitoring.  Several extension specialists and watershed coordinators from the North Central Region and beyond have consulted with the retaiN team to adapt the retaiN kit for their states.

For more information about the retaiN project, visit: www.retainiowa.com. 

Jamie Benning will discuss the retaiN project at the 2018 Iowa Water Conference. The full agenda will be available soon!

Jamie Benning is the Water Quality Program Manager with Iowa State University Extension and Outreach. She develops and delivers water quality and soil conservation programs and collaborates with researchers and extension specialists to create science-based education and training opportunities.  Benning works with external partners and stakeholders to support water quality improvement efforts throughout the state.

Winter Update from the IWC Graduate Student Research Grant Program: Emily Martin

Post submitted by Emily Martin, MS Environmental Science student at Iowa State University and recipient of the Graduate Student Supplemental Research Competition

Since the last update, we switched the focus of our study to the ability of biochar to remove nitrate in comparison to a woodchip-only bioreactor. As a reminder, the original goal of the project was to evaluate the ability of woodchip bioreactors to remove phosphorous by adding biochar as a phosphate (P) amendment. In the previous update, we found in a P sorption study that none of the biochars performed well at removing P from solution.

To compare nitrate removal, we ran what is called a batch reactor test. The batch test used five liter buckets filled with 30 grams of biochar, 350 grams of Ash woodchips, and three liters of deionized water. As a control to see the real impact of adding biochar, some buckets only contained woodchips. Both the test and control buckets had three types of denitrifying microbes added: Bradyrhizobium japonicum, Pseudomonas stutzeri, and DN-8A.

One issue that can arise not only in batch tests, but also in field woodchip bioreactors is an initial flushing of nutrients from the woodchips, and as we found out in the P sorption tests, also from biochar. To prevent this affecting our batch reactor tests, we allowed the mixture to soak for 24 hours. After the initial soak, the buckets were drained of the deionized water and two liters of nutrient solution was added. The nutrient solution was made to 30 mg/L NO3– and 10 mg/L PO42- using KNO3 and KH2PO4 – PO4 with deionized water, respectively. Samples were taken at 0, 4, 8, 12, and 24 hours to test for NO3—N.

Results showed that 12 of the 18 biochars removed more nitrate than the woodchip control. The biochar with the most removal was the 600°C Corn Stover, which almost doubled the amount of nitrate removed by the control. Of the 12 biochars that removed more nitrate than the control, 50 percent were 800°C, 25 percent were 600°C, and 25 percent were 400°C. All six of the 800°C biochars performed better than the control. The nitrate results overall were more promising than what was found in the P sorption test. There is potential to increase the ability of field bioreactors to remove nitrate by adding biochar; however, more tests will be needed to see how the biochar handles scaling up and field conditions. This was a short-term test in a laboratory setting. It is possible that on a larger scale, longer timescale, and at varying influent nitrate concentrations, biochar could perform worse than seen in the lab.

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A secondary part of the batch test was following up to the P sorption test. Because the biochar leached phosphorus in the P sorption test, the 24 hour soak in deionized water should have helped remove the initial leaching. We are still testing all of the biochars, but initial results from a set of three biochars and the woodchip control showed that all still leached phosphorus into the solution. This could be problematic for the use of biochar in field conditions and should be managed if tests are taken to full-scale.

The next step for the project is to finish testing for phosphorus removal from the batch tests. After that, a paper will be written and submitted for publishing. As conferences are coming up this spring, I will be creating a poster to present at the Iowa Water Conference (March 21-22) and the Environmental Science Graduate Student Symposium (April 4).