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Title: Investigating the double-impact of soil health promoting practices on water quality
Location: Boone
Time Period: 2019-2021
Research Team: Marshall D. McDaniel, Morgan P. Davis, Wendong Zhang, and John E. Sawyer
Project Description: A common assumption is that soil health promoting practices also reduce nitrate leaching and improve farm profits – but little evidence exists to back this up. That is until two recent, independent studies both showed that soil CO2 Burst, a soil health indicator and measure of microbial activity, negatively correlated with fertilizer nitrogen needed to achieve optimal corn yield. However, the link between the soil CO2 Burst and corn nitrogen needs remain highly variable, and the ability of management practices to increase CO2 Burst is largely unknown. This study will investigate this ‘Double Impact’ of soil health promoting practices – that is their ability to reduce nitrogen leaching AND increase soil nitrogen supply to crops.
Publications:
Funders: Iowa Nutrient Research Center
Disclaimer: This is an active research site, please contact the research team prior to planning any site visits.
Title: The Marsden farm experiment: A long-term investigation of how cropping system diversification and crop-livestock integration affect sustainability
Location: Iowa State University Marsden Farm, Boone, Co., Iowa
Time Period: 2001-present
Research Team: Matt Liebman and Matt Woods
Project Description: Sustainable farming practices are intended to minimize the use of non-renewable resources, decrease the emission of pollutants into water and air, retain and regenerate soil, and protect human health. They are also intended to maintain or increase farm productivity and profitability while reducing reliance on purchased inputs. A central tenet of sustainable farming systems is that careful stewardship of diverse ecological communities can be used to replace a substantial portion of the mineral fertilizers, synthetic pesticides, and petrochemical energy used in conventional farming systems.
Since 2001, we have used a 9-hectare (22-acre) field experiment at the Iowa State University Marsden Farm to investigate how cropping system diversification and crop-livestock integration affect productivity, profitability, and environmental quality. Three systems have been compared within the experiment: a 2-year corn/soybean rotation, a 3-year corn/soybean/oat + red clover rotation, and a 4-year corn/soybean/oat + alfalfa/alfalfa rotation. The 3-year and 4-year systems have periodically received cattle manure. By 2006, each of the plots had passed through at least one complete cycle of its respective rotation system.
For the ‘core set’ of comparisons among experimental treatments, the 2-year corn-soybean system has been managed with conventional rates of mineral fertilizers and herbicides, whereas the more diverse 3-year and 4-year systems have been managed with lower rates of agrichemicals. The experiment has also been used for a number of short-term component studies investigating a wide range of factors that can affect agroecosystem performance, including weed seed consumption by mice and insects, nitrogen mineralization from soil organic matter, and weed and crop responses to different ‘technology packages’ involving crop genotypes (transgenic versus non-transgenic) and weed control regimes (broadcast herbicides versus banded herbicides plus interrow cultivation).
Key results that have emerged from the study are as follows:
- During the period of 2006-2016, mineral N fertilizer use was 86% and 91% lower, and herbicide use was 96% and 97% lower in the 3-year and 4-year systems, respectively, than in the 2-year system.
- Corn yield has averaged 4% higher (p<0.0003) and soybean yield has averaged 16% higher (p<0.0001) in the more diverse systems compared with the 2-year system.
- Weed management has generally been effective regardless of rotation, with weed biomass in corn and soybean averaging <22 kilograms per hectare (20 lb per acre) in all systems.
- Incidence and severity of sudden death syndrome, a key disease affecting soybean in the Corn Belt, have been markedly lower in the longer rotations than in the 2-year rotation.
- Three indicators of soil quality–particulate organic matter carbon, microbial biomass carbon, and potentially mineralizable nitrogen–were 22% to 51% higher in the 3-year and 4-year rotations than in the 2-year rotation.
- Spring (March-May) concentrations of nitrate in drainage water collected from corn in the more diverse systems were 57% lower (p<0.005) than from corn in the 2-year system.
- Soil erosion was 50% lower, fossil energy consumption was 60% lower, and freshwater toxicity associated with herbicide use was 93% lower in the more diverse systems than in the conventional system.
- During 2008-2016, increases in rotation length led to greater labor requirements and decreased gross revenue. However, production costs also dropped substantially as cropping system diversity increased. Consequently, net returns to land and management did not differ among systems (p=0.56, mean=$845 per hectare per year, $342 per acre year), though profitability tended to rise as rotation length increased.
Collectively, results of this long-term study indicate that diversification of conventional corn-soybean systems with small grains and forage legumes, coupled with integration of those systems with livestock, can allow for large reductions in the use of mineral fertilizers and herbicides and lead to less environmental damage, equivalent profitability, improved soil quality, and higher crop productivity. Thus, the diversified, integrated crop-livestock systems we have investigated are in many ways more sustainable than a conventionally managed corn-soybean rotation. Translating these potential gains in agricultural sustainability into broad-scale changes in the U.S. Corn Belt will likely depend on combinations of factors that include government policies, farmer confidence, technical support, and markets for ‘non-conventional’ products.
Publications: Chen, X., X. Wang, M. Liebman, M. Cavigelli, and M. Wander. 2014. Influence of soil quality on carbon mineralization response to residue and nitrogen fertilizer additions. PLOS ONE 9(7): e103720, doi:10.1371/journal.pone.0103720.
Cruse, M.J., M. Liebman, D.R. Raman, and M. Wiedenhoeft. 2010. Fossil energy use in conventional and low-external-input cropping systems. Agronomy Journal 102: 934-941, doi:10.2134/agronj2009.0457; erratum: doi:10.2134/agronj2009.0457er.
Davis, A.S., J.D. Hill, C.A. Chase, A.M. Johanns, and M. Liebman. 2012. Increasing cropping system diversity balances productivity, profitability and environmental health. PLoS ONE 7(10): e47149. doi:10.1371/journal.pone.0047149.
Gómez, R., M. Liebman, and G. Munkvold. 2013. Weed seed decay in conventional and diversified cropping systems. Weed Research 54: 13-25.
Gómez, R., M. Liebman, D.N. Sundberg, and C.A. Chase. 2012. Comparison of crop management strategies involving crop genotype and weed management practices in conventional and more diverse cropping systems. Renewable Agriculture and Food 28: 220-233.
Heggenstaller, A.H. and M. Liebman. 2006. Demography of Abutilon theophrasti and Setaria faberi in three crop rotation systems. Weed Research 46: 138-151.
Heggenstaller, A.H., F.D. Menalled, M. Liebman, and P.R. Westerman. 2006. Seasonal patterns in post-dispersal seed predation of Abutilon theophrasti and Setaria faberi in three cropping systems. Journal of Applied Ecology 43: 999-1010.
Hunt, N., J. Hill, and M. Liebman. 2019. Cropping system diversity effects on nutrient discharge, soil erosion, and agronomic performance. Environmental Science and Technology, doi:10.1021/acs.est.8b02193.
Hunt, N., J. Hill, and M. Liebman. 2017. Reducing freshwater toxicity while maintaining weed control, profits, and productivity: effects of increased crop rotation diversity and reduced herbicide usage. Environmental Science and Technology 51: 1707–1717, doi:10.1021/acs.est.6b04086.
Jordan, N.R., and A.S. Davis. 2015. Middle-way strategies for sustainable intensification of agriculture. Bioscience 65: 513-519.
King, A.E., and K.S. Hofmockel. 2017. Diversified cropping systems support greater microbial cycling and retention of carbon and nitrogen. Agriculture, Ecosystems and Environment 240: 66-67.
Lazicki, P., M. Liebman, and M. Wander. 2016. Root parameters show how management alters resource distribution and soil quality in conventional and low-input cropping systems in central Iowa. PLOS ONE 11(10): e0164209, doi:10.1371/journal.pone.0164209.
Leandro, L.F.S., S. Eggenberger, C. Chen, J. Williams, G. Beattie, and M. Liebman. 2018. Cropping system diversification reduces severity and incidence of soybean sudden death syndrome caused by Fusarium virguliforme. Plant Disease 102, doi:10.1094/PDIS-11-16-1660-RE.
Liebman, M., B. Baraibar, Y. Buckley, D. Childs, S. Christensen, R. Cousens, H. Eizenberg, S. Heijting, D. Loddo, A. Merotto Jr., M. Renton, and M. Riemens. 2016. Ecologically sustainable weed management: How do we get from proof-of-concept to adoption? Ecological Applications 26: 1352–1369.
Liebman, M., L.R. Gibson, D.N. Sundberg, A.H. Heggenstaller, P.R. Westerman, C.A. Chase, R.G. Hartzler, F.D. Menalled, A.S. Davis, and P.M. Dixon. 2008. Agronomic and economic performance characteristics of conventional and low-external-input cropping systems in the central Corn Belt. Agronomy Journal 100: 600-610.
Liebman, M., M.J. Helmers, L.A. Schulte, and C.A. Chase. 2013. Using biodiversity to link agricultural productivity with environmental quality: results from three field experiments in Iowa. Renewable Agriculture and Food Systems 28: 115-128, doi:10.1017/S1742170512000300.
Liebman, M., Z.J. Miller, C.L. Williams, P.R. Westerman, P.M. Dixon, A.H. Heggenstaller, A.S. Davis, F.D. Menalled, and D.N. Sundberg. 2014. Fates of Setaria faberi and Abutilon theophrasti seeds in three crop rotation systems. Weed Research 54: 293–306.
Liebman, M. and L.A. Schulte. 2015. Enhancing agroecosystem performance and resilience through increased diversification of landscapes and cropping systems. Elementa: Science of the Anthropocene, doi:10.12952/journal.elementa.000041.
O’Rourke, M.E., A. Heggenstaller, M. Liebman, M.E. Rice. 2006. Post-dispersal weed seed predation by invertebrates in conventional and low-external-input crop rotation systems. Agriculture, Ecosystems and Environment 116: 280-288.
O’Rourke, M.E., M. Liebman, and M.E. Rice. 2008. Ground beetle (Coleoptera: Carabidae) assemblages in conventional and diversified crop rotation systems. Environmental Entomology 37: 121-130.
Osterholz, W., M. Liebman, and M.J. Castellano. 2018. Can soil nitrogen dynamics explain the yield benefit of crop diversification? Field Crops Research 291: 33-42, doi:10.1016/j.fcr.2018.01.026.
Osterholz, W.R., O. Rinot, M. Liebman, and M.J. Castellano. 2016. Can mineralization of soil organic matter meet maize nitrogen demand? Plant and Soil, doi:10.1007/s11104-016-3137-1.
Osterholz, W.R., O. Rinot, A. Shaviv, R. Linker, G. Sanford, J. Strock, M. Liebman, and M. Castellano. 2017. Predicting gross nitrogen mineralization and potentially mineralizable N using soil organic matter properties. Soil Science Society of America Journal, doi:10.2136/sssaj2017.02.0055.
Poffenbarger, H., G. Artz, G. Dahlke, W. Edwards, M. Hanna, J. Russell, H. Sellers, and M. Liebman. 2017. An economic analysis of integrated crop-livestock systems in Iowa, U.S.A. Agricultural Systems 157: 51-69, doi:10.1016/j.agsy.2017.07.001.
Poffenbarger, H.J., D.C. Olk, C. Cambardella, J. Kersey, M. Liebman, A. Mallarino, J. Six, and M.J. Castellano. 2020. Whole-profile soil organic matter content, composition, and stability under crop rotations differing in belowground inputs. Agriculture, Ecosystems, and Environment, doi:10.1016/j.agee.2019.106810.
Rinot, O., W. Osterholz, M.J. Castellano, R. Linker, M. Liebman, and A. Shaviv. 2018. Excitation–emission matrix fluorescence spectroscopy of water extractable organic matter to predict nitrogen mineralization rates in soil. Soil Science Society of America Journal, doi:10.2136/sssaj2017.06.0188.
Tomer, M.D. and M. Liebman. 2014. Nutrients in soil water under three rotational cropping systems, Iowa, USA. Agriculture, Ecosystems and Environment 186: 105-114.
Wattenburger, C.J., L.J. Halverson, and K.S. Hofmockel. 2019. Agricultural management affects root-associated microbiome recruitment over maize development. Phytobiomes Journal. doi: 10.1094/PBIOMES-03-19-0016-R.
Westerman, P.R., M. Liebman, F.D. Menalled, A.H. Heggenstaller, R.G. Hartzler, and P.M. Dixon. 2005. Are many little hammers effective? Velvetleaf population dynamics in two- and four-year crop rotation systems. Weed Science 53: 382-392.
Williams, C.L., M. Liebman, P.R. Westerman, J. Borza, D. Sundberg, and B. Danielson. 2009. Over-winter predation of Abutilon theophrasti and Setaria faberi seeds in arable land. Weed Research 49: 439–447.
Funders: USDA Agriculture and Food Research Initiative, Leopold Center for Sustainable Agriculture, Iowa Soybean Association, and Iowa Nutrient Research Center
Disclaimer: This is an active research site, please contact the research team prior to planning any site visits.
Title: Does quantity and quality of tile drainage water impact in-stream eutrophication potential? Evidence from a long-term biofuel cropping systems experiment.
Location: Boone
Time Period: 2019-2021
Research Team: Marshall D. McDaniel, Mriganka De, Michael L. Thompson, Matt Liebman, and Matthew J. Helmers
Project Description: The challenge with farming is balancing crop nutrient needs while minimizing losses. Fertilizer nitrogen (N) and phosphorus (P) are added to agricultural fields to increase yields, but these nutrients also limit algal growth in the aquatic ecosystems and in excess can lead to eutrophication. Tile drainage is used extensively across the U.S. Midwest to also improve yields, but these tile drainage lines can directly transport nutrients to streams - effectively bypassing natural stream buffers. The quantity (i.e. load) and quality (i.e. chemical composition of nutrients and carbon) of the tile drainage water likely plays a crucial role in stream water quality, but most tile drainage studies focus on only the quantity of total dissolved and inorganic forms of N and P. This, however, may not be giving us the whole story of how tile drainage water can affect stream water quality. Instead, we propose to delve further into the chemical forms of N and P (and dissolved organic carbon) in tile drainage water, and look at how management practices affect these. Furthermore, we will evaluate the eutrophication potential of the same tile water in order to gain a more comprehensive understanding of the effects of tile drainage water on stream water eutrophication. We will analyze tile drainage water samples from an ongoing, long-term experiment near Boone, IA called the Comparison of Biofuel cropping Systems (or COBS). The COBS experiment consists of five treatments: continuous corn, corn-soybean, corn with cover crop, fertilized prairie, and unfertilized prairie. Our specific research objectives are to:
1. Assess the impact of the five different management practices on chemical composition and bioavailability of dissolved organic matter in tile drainage water.
2. Determine the eutrophication potential of tile drain water from these different management practices.
Publications:
Funders: Iowa Nutrient Research Center
Disclaimer: This is an active research site, please contact the research team prior to planning any site visits.
Title: Perennial turfgrass cover crops in maize production systems
Location: Sorenson Research Farm, Ames
Time Period: 2019-2021
Research Team: Shui-zhang Fei, Ken Moore, Andrew Lenssen, and Allen Chen
Project Description: The current crop production system in the Midwest is highly productive but it negatively impacts the environment in a number of ways including non-point source nutrient pollution in waterways, soil erosion and declining soil quality. Growing annual cover crops can be a partial solution to these problems, however, the cost of annual planting, increased potential for corn root diseases, and the narrowed planting windows for subsequent crops continue to be hurdles to the widespread adoption of annual cover crops. Growing cool-season grasses with corn or soybean as perennial ground cover (PGC) provides similar benefits as annual cover crops but it does not require costly annual replanting or delayed planting of row crops. Many cool-season grasses that are commonly used as lawn grasses possess characteristics that make them ideal ground covers for maize and soybean: preference for cool, moist weather, shallow roots, good shade tolerance and winter hardiness. Our previous research indicated that Kentucky bluegrass grown concurrently with conventionally managed corn can produce comparable corn yields to a no-grass control, and Sandberg bluegrass which exhibits distinct summer dormancy can perform similarly. This proposal seeks to investigate the compatibility of PGC with maize by growing a diverse set of cultivars of Kentucky bluegrass and Sandberg bluegrass as PGC. We will investigate above and below-ground nutrient dynamics and the potential of using PGC to reduce non-point nitrogen and phosphorus pollution. Team members include Shuizhang Fei, professor of Horticulture, Andy Lenssen and Ken Moore, professors of Agronomy and Allen Chen, Ph.D. candidate.
Publications:
Funders: Iowa Nutrient Research Center
Disclaimer: This is an active research site, please contact the research team prior to planning any site visits.
Title: Evaluation of measurement methods as surrogates for tile-flow nitrate-N concentrations
Location: Agricultural Drainage Water Quality Site, Gilmore City, IA: Iowa State University Northwest Research Farm, Sutherland, IA
Time Period: 2017-2019
Research Team: John Sawyer, Matt Helmers, and Girma Birru
Project Description: Nitrogen management practice effects on nitrate loss to surface waters are best determined through measurement of nitrate-N concentrations in tile water flow at specially developed water quality sites. However, these sites are expensive to develop and maintain. In addition, the number of treatments that can be compared is limited due to physical constraints on the number of plots. With a common need to determine N reduction practice effects with multi-year rotations, such as corn following soybean, the number of drainage plots available for different practice evaluation becomes even more limited. Surrogate methods need to be developed that allow evaluation of N management practices that reasonably estimate nitrate-N concentrations comparable to measurement in tile flow drainage. If successful, surrogates could be used on land that is not suitable for tile drainage, but where ground water recharge supplies water (and potential nitrate-N) to surface water systems.
Objective:
The objective of this project is to relate two measurement methods as surrogates to tile-flow nitrate-N concentrations, then measure the effects of two N reduction management practices on nitrate-N via the surrogate measures and loss in tile drainage.
Approach:
The research will include two surrogate methods, measuring soil nitrate-N and soil solution nitrate-N concentrations. Sampling will be done by probing the soil profile and with suction lysimeters. To make the comparison with tile-flow nitrate-N concentrations, two existing water quality tile drainage sites in Iowa will be used, with two nitrogen management practices. Other on-going data being collected also will be available, such as crop production practices, crop yields, and grain N content.
Publications:
Funders: Iowa Nutrient Research Center and Iowa Nutrient Research and Education Council
Disclaimer: This is an active research site, please contact the research team prior to planning any site visits.
Title: Evaluation of saturated buffers as a conservation drainage practice for treating agricultural subsurface drainage
Location: Roland, Dysart, Ellsworth, Colo and Slater
Time Period: 2018-2020
Research Team: Chris R. Rehmann, Michael A. Perez, Cassandra J. Rutherford, Thomas M. Isenhart, Dan B. Jaynes, Andrea R. McEachran and Loulou C. Dickey
Project Description: This study involves the use of MODFLOW and analytical modeling to gain a better understanding of how saturated riparian buffers function, in terms of groundwater flow and nitrate transport and removal. Suggestions for improving the design of saturated riparian buffers in terms of nitrate removal will be made based on the findings from the models.
Publications: McEachran, A.R., Dickey, L.C., Rehmann, C.R., Perez, M.A., Rutherford, C.J., and Groh, T.A. 2019 Effectiveness of saturated riparian buffers for removing nitrate from subsurface drainage, in preparation for J. Environmental Quality.
Funders: Iowa Nutrient Research Center
Disclaimer: This is an active research site, please contact the research team prior to planning any site visits.
Title: Bayer-ISU Water Quality Partnership
Location: Story County
Time Period: 2018-present
Research Team: Sortirios Archontoulis, Mike Castellano, and Matt Helmers
Project Description: Advances in cropping systems technology – including genetics and management – have the potential to increase crop productivity and improve water quality. This project uses a research site that includes 48, half-acre, independently drained plots that were donated by Bayer and The Climate Corporation. This research infrastructure has created an unprecedented ability to understand how future advances in genetics and management can be used to improve water quality.
Publications:
Funders: Bayer and Iowa State University
Disclaimer: This is an active research site, please contact the research team prior to planning any site visits.
Title: Bioreactor research & assessment of woodchip tile denitrification bioreactors: Optimal design/performance and experimental bioreactor installation and study
Location: Iowa State University Ag Engineering and Agronomy Farm, Boone
Time Period: 2013-2016
Research Team: Michelle Soupir, Natasha Hoover, Timothy Goode, and Richard VanDePol
Project Description: A total of nine pilot-scale bioreactors were installed in 2014, and initial characteristic evaluation was completed in 2015. The reactors were designed to maximize flexibility in experimental design, allowing for potential variation in the main parameters influencing bioreactor performance: influent water quality, HRT, and bioreactor fill material. The pilot-scale bioreactor research site at the ISU ABE Research Farm is a valuable tool for evaluating denitrification bioreactors, allowing for control of multiple factors under environmental conditions representative of changing field conditions.
Publications: Hoover, N.L., M.L. Soupir, R.D. VanDePol, T.R. Goode, J.Y. Law. 2016. Technical Note: Pilot-Scale Denitrification Bioreactors for Replicated Field Research. Applied Engineering in Agriculture 33(1): 83-90.
Funders: Iowa Nutrient Research Center
Disclaimer: This is an active research site, please contact the research team prior to planning any site visits.
Title: Impacts of cover crops on P and N loss with surface runoff
Location: Boone County
Time Period: 2015-present
Research Team: Antonio Mallarino, Matthew Helmers, Richard Cruse, John Sawyer, and Dan Jaynes
Project Description:
Issue: Cover crops are a recognized conservation practice to reduce soil erosion, and Iowa research has shown a winter cereal rye cover crop greatly reduces nitrate loss with subsurface drainage. However, little research has evaluated the impact of cover crops on total and dissolved nitrogen (N) and phosphorus (P) loss with surface runoff.
Objective: This project will continue an existing study for two more years, conducted under natural rainfall, to evaluate impacts of a winter cereal rye cover crop on soil, N, and P loss with surface runoff in a field testing high in P, managed with a corn-soybean rotation. Approach: Systems evaluated in 12 areas ranging from one to three acres are chiselplow/disk tillage and no-tillage with or without a cereal rye cover crop seeding each year. Soil samples for the late-spring nitrate test are collected when corn is 6 to 12 inches tall. Dry matter yield and total P and N are measured in rye cover crop samples collected each spring and fall to study nutrient uptake and recycling into the soil. Grain yield, grain N and P concentrations, and removal are measured each year. Runoff from the test areas is analyzed for total solids and several P and N forms.
Publications:
Funders: Iowa Nutrient Research Center
Disclaimer: This is an active research site, please contact the research team prior to planning any site visits.
Title: SERF wetland
Location: Southeast Research and Demonstration Farm
Time Period: 2007-present
Research Team: Kristina TeBockhorst, Carl Pederson, and Matt Helmers
Project Description: The purpose of this project was to demonstrate the reductions in nitrate-nitrogen concentrations that can be achieved with a constructed wetland. The constructed wetland is located at the Southeast Research Farm near Crawfordsville, IA. It receives subsurface drainage from 30 acres of a drainage water management study. The wetland was constructed to have a water depth of 0 to 3 ft. Berms were constructed to force the water to follow a serpentine route as it flows through the wetland. The wetland was constructed to have a surface area of approximately one percent of the drained area. With 30 acres of subsurface coming into the wetland, it was sized with a surface area of 0.3 to 0.4 acres. Water levels in the wetland can be controlled with head control structure on the outlet of the wetland. Because denitrification requires a growth of vegetation, cattail cuttings were planted in the spring of 2007. Good growth was achieved in 2007 with the cattails establishing well in 2008.Water flow rates into and out of the wetland were monitored using V-notch weirs and pressure transducers and water samples were taken by grab sampling inflow and outflow on a weekly basis for assessment of nitrate-nitrogen levels.
Publications:
Funders: The project was initially funded by a State Conservation Innovation Grant from USDA-NRCS.
Disclaimer: This is an active research site, please contact the research team prior to planning any site visits.