Source: PURDUE UNIVERSITY submitted to
ASSESSMENT OF WATER QUALITY IMPACTS OF CONSERVATION PRACTICES FOR SUBSURFACE-DRAINED AGRICULTURAL WATERSHEDS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
1000002
Grant No.
(N/A)
Project No.
IND010669
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Oct 1, 2013
Project End Date
Sep 30, 2018
Grant Year
(N/A)
Project Director
Frankenberger, JA.
Recipient Organization
PURDUE UNIVERSITY
(N/A)
WEST LAFAYETTE,IN 47907
Performing Department
Ag & Biological Engineering
Non Technical Summary
Billions of dollars are being spent for the design and implementation of agricultural conservation practices with the primary goal of reducing nonpoint source pollution from agriculture. Subsurface drainage is an important component of modern agriculture, and is used extensively within agricultural fields in Indiana and other regions of the Midwest. Nitrate that leaches through the root zone of drained fields flows through the tiles and directly enters the surface water. It is critical to design computer based models to help farmers and landowers control water in thier fields while minimizing the leaching of fertilizers.
Animal Health Component
0%
Research Effort Categories
Basic
(N/A)
Applied
70%
Developmental
30%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1120320202050%
1120320205050%
Knowledge Area
112 - Watershed Protection and Management;

Subject Of Investigation
0320 - Watersheds;

Field Of Science
2020 - Engineering; 2050 - Hydrology;
Goals / Objectives
The overall goal is to quantify potential water quality improvements due to conservation practices used in subsurface-drained agricultural watersheds. Specific objectives are: Assess the potential of improved drainage management practices to reduce nitrate loads from subsurface tile drained fields Extend the field-scale results to estimate potential impacts at the watershed scale of these improved drainage management practices using statistical analysis and simulation models. Improve modeling tools and their use for estimating reductions in nonpoint source load due to implementation of agricultural conservation practices
Project Methods
Drainage water management is the practice of managing the height of the drainage outlet to reduce nitrate transport from tiles during the fallow season and potentially to reduce water deficit stress during the growing season. The impacts of this practice at the field scale will be studied through field monitoring of paired sites at a drainage research site established at the Davis Purdue Agriculture Center in collaboration with L. Bowling and E. Kladivko, which includes two pairs of sub-fields approximately 4 hectares in area. Hourly drain flow will be measured using electromagnetic flow meters. Soil moisture will be collected at five depths in the soil profile at 5-minute intervals using capacitance-type meters, and water table will be measured hourly in observation wells equipped with automated water level meters. The impacts of drainage water management will be determined using a paired field statistical analysis of drain flow, while the soil moisture and water table measurements will provide additional explanatory variables to better understand the hydrologic processes. At the watershed scale, estimating water quality impacts of conservation practices usually relies on models. Watershed-scale simulation of tile-drained watersheds with monitoring data available will be conducted primarily using the Soil and Water Assessment Tool (SWAT model). Although tile drainage simulation has been possible using this model for a number of years, a new version of the tile drainage routine (Moriasi et al., 2012) has been recently introduced and is expected to improve simulations in highly-drained watersheds. However, the new routine has not been widely tested, and has not been evaluated at all in the eastern Corn Belt. Parameters controlling the simulation of tile drains and the nitrogen cycle will be calibrated, and parameters will be compared to try to determine regional values, which could provide starting points for modeling in unmonitored watersheds. Preliminary studies have shown that model results are most sensitive to three nitrogen parameters: the rate coefficient for m Complex desktop modeling tools like SWAT are not appropriate for many decision-makers. More of the input data needed to run the models, including geospatial inputs such as soils, elevation, land use, and cropping patterns, and also weather data are becoming available online as web services, which can facilitate the modeling process. These new GIS data handling methods provide an opportunity to develop new ways for users to access models, including simple web interfaces and also mobile applications known as"apps". Using mobile computing technology in the field to access existing on-line databases and complex models can improve the efficiency and quality of the decision making process. We will focus on developing applications using the new statewide LiDAR data such as watershed delineation in the field, which can greatly increase the speed at which conservation designs can be developed and discussed with landowners.

Progress 10/01/13 to 09/30/18

Outputs
Target Audience:Farmers, watershed managers, drainage contractors,conservation agency staff who make decisions about conservation practices, including USDA Natural Resources Conservation Service and state departments of agriculture. Also, participants at conferences such as American Society of Agricultural and Biological Engineers, Ag Drainage Management Systems Task Force. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Four graduate students have been trained. How have the results been disseminated to communities of interest?This year, we reported findings at the American Society of Agricultural and Biological Engineers International Meeting, the Transforming Drainage project meeting, and numerous Extension and other training workshops and webinars at state, regional, and national levels. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? We completed 10 years of monitoring controlled drainage at a field site with two pairs of free and controlled drainage in eastern Indiana, and found that this practice significantly reduced drain flow and nitrate. Over the ten years, the reduction was 68% in the eastern pair and 58% in the western pair during controlled drainage at the higher outlet level (winter) and 64% and 58% at the lower outlet level (summer) in the eastern and western pairs, respectively. The effect of controlled drainage on phosphorus loads was not significant, except for an increase in SRP in one pair.These results using two different statistical methods support this management practice as a reliable system for reducing nitrate loss through subsurface drains, which can be used in drained landscapes to support nutrient reduction goals.

Publications

  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Andresen, J.A. and Brown, L.C., 2018. Modeled climate change impacts on subirrigated maize relative yield in northwest Ohio. Agricultural Water Management, 206, pp.56-66.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Saadat, S., Bowling, L., Frankenberger, J. and Kladivko, E., 2018. Nitrate and phosphorus transport through subsurface drains under free and controlled drainage. Water Research.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Shao, G., Shao, G., Gallion, J., Saunders, M.R., Frankenberger, J.R. and Fei, S., 2018. Improving Lidar-based aboveground biomass estimation of temperate hardwood forests with varying site productivity. Remote Sensing of Environment, 204, pp.872-882.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Koundinya, V., Baird, A., Klink, J., Wolfson, L., Frankenberger, J., Bonnell, J. and Power, R., 2018. Core Competencies for Successful Watershed Management Practitioners. Journal of Extension, 56(1).


Progress 10/01/16 to 09/30/17

Outputs
Target Audience:Conservation agency staff who make decisions about conservation practices, including USDA Natural Resources Conservation Service and state departments of agriculture. Farmers, watershed managers, drainage contractors, participants at conferences such as American Society of Agricultural and Biological Engineers,Ag Drainage Management Systems Task Force. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?1 PhD student and 1 MS student are being trained. How have the results been disseminated to communities of interest?The Agricultural Drainage Management Systems Task Force, which includes representatives from ARS, NRCS, land-grant universities, NIFA, USGS, State Departments of Agriculture, and the drainage industry, is a major way that .drainage research is discussed with action agenciesand I have led the organization of the meeting each year. I presented information on drainage management to 655 people in nine Extension presentations. Audience members included staff from federal, state, and local agencies; commodity groups; drainage contractors; crop advisors, seed dealers; and producers. I also spoke to 4567 students at 61 schools from 13 states through a Purdue University "zip trip" virtual field trip for high school students about practices that store drainage water to increase resilience of drained agriculture.I co-led the International Drainage Symposium, held in Minneapolis, MN in 2016, where more than 200 people gathered to share information. What do you plan to do during the next reporting period to accomplish the goals?This year we will focus on the synthesis of our controlled drainage results with those from other sites around the Midwest in the Transforming Drainage project. This will allow us to develop regional recommendations for controlled drainage management. We are also beginning research on a new practice, drainage water recycling. We will share improved methods of simulating tile drainage within the Soil and Water Assessment Tool (SWAT) model. We will report our findings at conferences and extension events.

Impacts
What was accomplished under these goals? We completed eleven years of monitoring drain flow, soil moisture at five depths, water table depth, and tile flow nitrate concentration at the Davis Purdue Agricultural Center. Our analysis of results from the two free draining and two controlled drainage quadrants of the field shows that controlled drainage reduced drain flow by 14% to 49%, with similar reductions in nitrate load. In addition to publishing the results, the data have been provided data to the shared database managed by the Transforming Drainage team at Iowa State University. These data were also used to address the management of controlled drainage. We examined whether the outlet should be lowered prior to or directly after a rainfall event to reduce the amount of time that the water table is at a level that would be detrimental to either trafficability or crop yield. We determined water table recession rates from two pairs of controlled and free-draining fields located at the Davis Purdue Agricultural Center in Indiana over a period of 9 years from 2006 to 2014. For each pair, comparison of mean recession rate from the two fields indicated that controlled drainage reduced recession rate. Raising the outlet of the subsurface drainage system decreased the mean rate of water table recession by 29% to 62%, increasing the time needed for the water table level to fall from the surface to 60 cm depth by approximately 24 to 53 hours. Based on these results, lowering the outlet before storm events would reduce the amount of time that the water table is at a detrimental level for either crop growth or trafficability. However, the trade-off between costs and benefits of active management depends on the sensitivity of the crop and probability of a severe storm. The Transforming Drainage regional project has brought together agronomic, soil, hydrologic, water quality, and weather data at 16 experimental sites in 8 states, to quantify the impacts of the three drainage storage practices addressed in the project (controlled drainage, saturated buffers, and drainage water recycling). The database framework that has been developed for managing experimental data will support coordinated synthesis and modeling of drainage storage approaches. It includes 34 experimental drainage sites across 8 states representing 186 site-years of data and containing 85 field measurement, 91 field management, and 25 weather data types to allow for characterization of production and water quality impacts across drainage water storage practices. We launched the website, http://transformingdrainage.org, to serve as portal for drainage stakeholders and the general public to access project updates and information and interact with products and materials.

Publications

  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Saadat, S., Bowling, L., Frankenberger, J. and Brooks, K., 2017. Effects of Controlled Drainage on Water Table Recession Rate. Transactions of the ASABE, 60(3), p.813. doi: 10.13031/trans.11922.
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Hodaj, A., Bowling, L.C., Frankenberger, J.R. and Chaubey, I., 2017. Impact of a two-stage ditch on channel water quality. Agricultural Water Management, 192, pp.126-137. doi:10.1016/j.agwat.2017.07.006
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Baule, W., Allred, B., Frankenberger, J., Gamble, D., Andresen, J., Gunn, K.M. and Brown, L., 2017. Northwest Ohio crop yield benefits of water capture and subirrigation based on future climate change projections. Agricultural Water Management, 189, pp.87-97.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Ross, J.A., Herbert, M.E., Sowa, S.P., Frankenberger, J.R., King, K.W., Christopher, S.F., Tank, J.L., Arnold, J.G., White, M.J. and Yen, H., 2016. A synthesis and comparative evaluation of factors influencing the effectiveness of drainage water management. Agricultural Water Management, 178, pp.366-376. doi:10.1016/j.agwat.2016.10.011


Progress 10/01/15 to 09/30/16

Outputs
Target Audience:Farmers, watershed managers, drainage contractors, USDA Natural Resources Conservation Service and state departmentsof agriculture, participants at conferences such as American Society of Agricultural and Biological Engineers, Ag Drainage Management Systems Task Force. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Three graduate students have been trained. How have the results been disseminated to communities of interest?We have reported findings at conferences including the American Society of Agricultural and Biological Engineers International Meeting, Tri-Societies meeting, and the International Drainage Sympoisum. We have presented the research at numerous Extension and other training workshops and webinars at state, regional, and national levels. What do you plan to do during the next reporting period to accomplish the goals?We will continue field monitoring of our drainage water management site, and analysis of drain flow and nitrate loads from free and controlled drainage. We will work with researchers in other states with similar research to synthesize findings and develop recommendations for controlled drainage management. We will share improveds methods of simulating tile drainage within the Soil and Water Assessment Tool (SWAT) model. We will report our findings at conferences and extension events.

Impacts
What was accomplished under these goals? Weassessed the nitrate and phosphorus reductions due to controlled drainage at theDavis Purdue Agriculture Center in Indiana and found that over four years (2012-2015)controlled drainage decreased nitrate load by 4.4 kg/ha in one paired set of plotsand by 2.6 kg/ha in the other. Controlled drainageslightly increased soluble reactive phosphorusand total phosphorusloads, byless than 0.1 kg/ha. The nitrate reductions are in general less than other researchers have found, possibly because our field has somewhat restricted drainage.We also examined the soil moisture impacts of controlled drainage at DPAC and at three other sites in Ohio, Minnesota, and Iowa and their relationship to yield. Late-season deficit and early-season excess soil moisture were indicators of yield reductions, and deficit soil moisture stress was higher in the free draining fields. Fewsignificant differences were found in excess stress between free and controlled drainage, and thus yield reductions predicted in some simulations due to excess moisture stress were not found in the years studied. We also examined the potential for controlled drainage to lengthenthe time needed for the water table to fall after a rainfall event to inform the possible improvement in the management of controlled drainage system. At DPAC, we found thatcontrolled drainage had a statistically significant effect on the rate of water table fall, and that a raised outlet (controlled drainage) increased the time of water table recession. Therefore, lowering the outlet before storm events would reduce the amount of time that the water table is at a detrimental level for either crop growth or trafficability. We made improvements to the tile drainage routine in theSoil and Water Assessment Tool (SWAT) to better represent the hydrologic processes related to subsurface drainage, First, percolation through the soil profile was altered to be based on Darcy's Law and the Buckingham-Darcy Law. Second, the restrictive layer of the soil profile was redefined to be the bottom of the soil profile and an additional variable was added to control the seepage through the restrictive layer. Third, the water table height algorithm, which was based on an algorithm applicable at only one site, was redefined to be within the lowest unsaturated layer. Lastly, the lag through the tile drains, which caused an unrealistic delay under default conditions was removed and flow is delayed by only the drainage coefficient.These changes were evaluated at the experimental tile drained field at the Southeast Purdue Agricultural Center (SEPAC) and on a small watershed located in Central Ohio monitored by the USDA-ARS.These modifications improved the physical basis or simplified the process representation in the SWAT model, and showed improvement to the tile flow model predictions.

Publications

  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Her, Y., Chaubey, I., Frankenberger, J. and Smith, D., 2016. Effect of conservation practices implemented by USDA programs at field and watershed scales. Journal of Soil and Water Conservation, 71(3): 249-266. doi: 10.2489/jswc.71.3.249.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Her, Y., Chaubey, I., Frankenberger, J. and Jeong, J., 2016. Implications of spatial and temporal variations in effects of conservation practices on water management strategies. Agricultural Water Management. http://dx.doi.org/10.1016/j.agwat.2016.07.004
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Boles, C.M., J.R Frankenberger, and D.N. Moriasi, 2015. Tile Drainage Simulation in SWAT2012: Parameterization and Evaluation in an Indiana Watershed. Transactions of the ASABE, 58(5), pp.1201-1213. doi: 10.13031/trans.58.10589.
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Zeckoski, R.W., M. Smolen, D. Moriasi, J. Frankenberger, and G. Feyereisen, 2015. Hydrologic and water quality terminology as applied to modeling. Transactions of the ASABE 58(6): 1619-1635. doi: 10.13031/trans.58.10713.
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Saraswat, D., J. Frankenberger, N. Pai, S. Ale, P. Daggupati, K. Douglas-Mankin, and M. Youssef, 2015. Documentation and reporting procedures for calibration, validation, and use. Transactions of the ASABE, 58(6): 1787-1797. doi: 10.13031/trans.58.10707.


Progress 10/01/14 to 09/30/15

Outputs
Target Audience:Farmers, Conservation agency staff such as USDA Natural Resources Conservation Agency and state department of agriculture, Watershed managers,participants at conferences such as American Society of Agricultural and BIological Engineers, Ag Drainage Management Systems Task Force. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Three graduate students have been trained. How have the results been disseminated to communities of interest?We have reported findings at numerous conferences including the American Society of Agricultural and Biological Engineers, the Agricultural Drainage Management Systems Task Force, the Sustainable Corn Annual Meeting. We have presented to the Certified Crop Advisors conference, the Indiana Watershed Leadership Academy, numerousExtension workshops, and webinars to farmers, watershed managers, and conservation agency staff. What do you plan to do during the next reporting period to accomplish the goals?We will continue field monitoring of our drainage water management site, and analysis of drain flow and nitrate loads from free and controlled drainage. We will improve methods of simulating tile drainage within the Soil and Water Assessment Tool (SWAT) model and evaluate its performance at the field scale. We will report our findings at conferences and extension events.

Impacts
What was accomplished under these goals? The Soil and Water Assessment Tool (SWAT) is used to relate farm management practices to their impacts on surface waters at the watershed scale. We implemented several innovations to improve and demonstrate its usefulness in making decisions about conservation practices to improve water quality. First, we developed a way to define ahydrologic response unit (HRU).the smallest spatial unit of the model, by field boundary. The standard HRU definition approach lumps all similar land uses, soils, and slopes within a subbasin based upon user-defined thresholds, whichprovides an efficient way to discretize large watersheds where simulation at the field scale may not be computationally feasible. In relatively smaller watersheds, however, defining HRUs to specific spatial locations bounded by property lines or field borders would often be advantageous. Predictions of nitrogen, phosphorus, and sediment losses were compared in a case study watershed where SWAT was set up using both the standard HRU definition and field boundary approach. Watershed-scale results were reasonable and similar for both methods, but aggregating fields by majority soil type masked extremely high soil erosion predicted for a few soils. Results from field-based HRU delineation may be quite different from the standard approach due to choosing a majority soil type in each farm field. This approach is flexible such that any land use and soil data prepared for SWAT can be used and any shapefile boundary can divide HRUs. Second, we demonstrated an innovative method to targetagricultural conservation practices to the most effective locations in a watershed, in order topromote wise use of conservation funds to protect surface waters from agricultural nonpoint source pollution. A spatial optimization procedure using the Soil and Water Assessment Tool was used to target six widely used conservation practices, namely no-tillage, cereal rye cover crops (CC), filter strips (FS), grassed waterways (GW), created wetlands, and restored prairie habitats, in two west-central Indiana watersheds. We alsouseda mixed qualitative and quantitative method to understand farmer knowledge of ecosystem services and willingness to manage lands from an ecosystem perspective. Knowledge gained may help in applying the ecosystem services concept to agricultural management. We also continue monitoring drain flow, water table, and soil moisture at the Davis Purdue AgriculturalCenter drainage water management research site.

Publications

  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Kalcic, M., Frankenberger, J., and I. Chaubey. 2015. Spatial optimization of six conservation practices using SWAT in tile-drained agricultural watersheds. Journal of the American Water Resources Association (JAWRA). DOI: 10.1111/1752-1688.12338.
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Kalcic, M., Frankenberger, J., Chaubey, I., Prokopy, L., and L. Bowling. 2015. Adaptive targeting: engaging farmers to improve targeting and adoption of agricultural conservation practices. Journal of the American Water Resources Association (JAWRA). DOI: 10.1111/1752-1688.12336.
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: King, K. W., Williams, M. R., Macrae, M. L., Fausey, N. R., Frankenberger, J.R., Smith, D. R.,Kleinman, P.J., & Brown, L. C., 2014. Phosphorus transport in agricultural subsurface drainage: A review. Journal of Environmental Quality. http://dx.doi.org/10.2134/jeq2014.04.0163.
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Logsdon, R.A., M.M Kalcic, E.M. Trybula, I. Chaubey & J. R. Frankenberger, 2015. Ecosystem services and Indiana agriculture: farmers and conservationists perceptions, International Journal of Biodiversity Science, Ecosystem Services & Management, DOI: 10.1080/21513732.2014.998711
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Kalcic, M., I. Chaubey, J. Frankenberger, 2015. Defining SWAT hydrologic response units (HRUs) by field boundaries. International Journal of Agricultural and Biological Engineering, 8.1 (2015).


Progress 10/01/13 to 09/30/14

Outputs
Target Audience: Farmers, USDA Natural Resources Conservation Agency staff, participants at conferences such as Ag Outlook inWashington DC, American Society of Agricultural and BIological Engineers, Ag Drainage Management Systems Task Force. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Two graduate students have been trained. Current findings on drainage water management impacts have been shared at conferences, Extension meetings, and online, to farmers, agricultural advisors, and conservation agencies. How have the results been disseminated to communities of interest? We have presented the results to farmers, drainage contractors, and conservation agency staff at numerous Extension workshops, the "Resilient Agriculture: Adapting to a Changing Climate" conference, and training for NRCS staff on drainage water management. The Agricultural Drainage Management Systems Task Force continues to be an important forum for discussions between researchers, agency staff, and the drainage industry through which results are disseminated. What do you plan to do during the next reporting period to accomplish the goals? We will continue to monitor drain flow, water table, and soil moisture because more years of data are needed to answer the research questions. We are increasing regional analysis of results to answer questions about drainage water management effectiveness across the the range of climate conditions in the Corn Belt, from Minnesota to Ohio.

Impacts
What was accomplished under these goals? To analyze the impacts of drainage water management, we have collected continuous drain flow, soil moisture at five depths, and water table depth measurements for two fields with drainage water management and two without in east-central Indiana. We analyzed 22 events and found that, as expected, total event drain flow decreased and the time to peak increased. These hydrologic analyses are helping us understanding the processes taking place in subsurface-drained fields, alterations due to drainage water management, and the potential of the practice to decrease nitrate loads. Targeting of agricultural conservation practices, such as those addressing subsurface drainage, could lead to more effective management of nonpoint source pollution from agricultural lands, yet practical implementation of targeted solutions has lagged. We used farmer interviews in Indiana to better understand farmers’ views on targeting. Interviews discussed adoption of a number of conservation practices on farmers’ lands, as well as identified farmers’ views on targeting, disproportionality, and monetary incentives. Results show consistent support for the targeting approach across all interviews, despite dramatic differences in farmers’ views of land stewardship, their views about disproportionality of water quality impacts, and their trust of government programs. While the theoretical concept of targeting was palatable to all farmers, most farmers raised concerns related to targeting’s practical implementation, including the need for flexibility and the image of the entity performing targeting. We investigated the statistical relationship between subsurface tile drainage and nitrate-N concentrations in watersheds across Indiana, and found that a strong linear relation exists between the flow-weighted nitrate-N concentration from nonpoint sources and tile drained area percentage. The resulting predictions could be used as a simple yet effective tool to estimate nitrate-N concentrations in unmonitored watersheds in Indiana and similar areas. If the estimated concentrations are converted to loads, they can be compared with target nitrate-N loads to provide a basis for estimating the amount and type of conservation activities needed to achieve water quality goals.

Publications

  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Kalcic, M., Prokopy, L., Frankenberger, J., & Chaubey, I. An In-depth Examination of Farmers Perceptions of Targeting Conservation Practices. Environmental Management, 2014. DOI: 10.1007/s00267-014-0342-7
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Kladivko, EJ, MJ Helmers, LJ Abendroth, D Herzmann, R. Lal, MJ Castellano, DS Mueller, JE Sawyer, RP Anex, RW Arritt, B Basso, JV Bonta, LC Bowling, RM Cruse, NR Fausey, JR Frankenberger, PW Gassman, AJ Gassmann, CL Kling, A Kravchenko, JG Lauer, FE Miguez, ED Nafziger, N Nkongolo, M ONeal, LB Owens, PR Owens, P Scharf, MJ Shipitalo, JS Strock, MB Villamil. Standardized Research Protocols Enable Transdisciplinary Research of Climate Variation Impacts in Corn Production Systems. Journal of Soil and Water Conservation, 69(6):532-542; doi:10.2489/jswc.69.6.532
  • Type: Journal Articles Status: Awaiting Publication Year Published: 2014 Citation: Jiang Y., Y. Sui, J. Frankenberger and L. C. Bowling, Estimation of Nonpoint Source Nitrate Concentrations in Indiana Rivers Based on Agricultural Drainage in the Watershed, J. American Water Resource Association, in press.
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Jiang, Y., J. R. Frankenberger, L.C. Bowling, Z. Sun. Quantification of Uncertainty in Estimated Nitrate-N Loads in Agricultural Watersheds. Journal of Hydrology, 519:106-116. doi:10.1016/j.jhydrol.2014.06.027.