Category: Statewide

The state of Iowa is under increasing pressure to improve agronomic efficiency while mitigating soil and water degradation. Predictive agroecosystem process models are used to target solutions for soil and water quality issues in Iowa by quantifying degradation and monitoring the efficacy of sustainable land management practices. The problem is that these models are sensitive to soil input data. Currently available soil maps are outdated and lack the spatial resolution required to meet the needs of precision agroecosystem modeling. The Soil Survey Geographic (SSURGO) database is considered the ‘best available’ source for spatial soil information, however, these maps were built from data over 30years old. Moreover, technological advancements since the production of SSURGO maps greatly exceed those used to make them. We propose to make “next generation” soil maps via Digital Soil Mapping (DSM) techniques for soil properties pertinent to agroecosystem model predictions to support monitoring and mitigating water quality.Specifically, these soil properties are thickness of A horizon, 2) depth to permanent saturation (water table), 3) particle size fractions (sand, silt, and clay) and 4)Soil Organic Carbon(SOC)content. In support of our current DSM project in Story and Boone Counties, we propose a comparative “quad-county” study region in Osceola, Clay, Emmet, and Dickinson Counties. The quad-county region encompasses different soil and drainage characteristics on sub-regions of the Des Moines Lobe (DML) that are frequently overlooked.

The objectives of this study are to: 1) produce digital soil maps for the target soil properties have greater accuracy and spatial resolution than the currently available SSURGO maps, and 2) test the transferability of the spatial models used to produce the digital soil maps for their ability to predict soil variation on the greater DML region. Preliminary analysis on the two study regions with a limited pool of environmental covariates and existing soil datasets found that predictive maps created by DSM methods outperformed SSURGO predictions. For example, the RMSE for A horizonthickness was reduced from 25.7 cm for SSURGO to 13.7 cm for the digital soilmap. Similar reductions in uncertainty from SSURGO to the digital soil map were achieved for depth to water table (30.3 reduced to 17.6 cm), sand content (12.3 reduced to 7.8%), and silt content (9.5 reduced to 7.1%). Project deliverables will include 3-meter resolution maps of predicted target soil properties and their estimated error for the two study regions. Maps for particle size fractions and SOC content will be generated at six depth intervals down to two meters. Comparative performance against equivalent SSURGO maps and model transferability to the greater DML region will be evaluated and reported.

In this project we propose to evaluate three common farm-animal antibiotics, chlortetracycline (Aureomycin), oxytetracycline (Terramycin) and erythromycin (a macrolide) with respect to their fate in Iowa’s soil/water environment. The expected results of this study will involve three aspects concerning fate of antibiotics. One aspect will involve elucidation of surface sorption of the selected antibiotics by organic and inorganic soil components. A second aspect will involve elucidation of the role of sorption on antibiotic mobility in soil, and a third aspect will involve half-life quantification of the selected antibiotics and cooperative or anti-cooperative contributions of the organic and inorganic surface-antibiotic interactions to the abiotic/biotic degradation process. The results from this project will allow us to elucidate and predict the potential long-term consequences of antibiotics with respect to their potential distribution and persistence in Iowa’s soil/water system. This type of information is of paramount importance in understanding the fate of antibiotics in the soil/water environment and proposing potential solutions to the problem.

This project integrates the research base on nonpoint source pollution control and watershed modeling and Geographic Information Systems (GIS) developed at Iowa State University’s Department of Agricultural and Biosystems Engineering with research capabilities at other centers and departments on campus to focus on key issues which will be faced in Iowa in implementing TMDLs on impaired watersheds and water bodies. The long-term goal of this project is to focus on developing critically needed decision support framework for enhancing the TMDL decision-making and implementation process by combining relevant information on in-stream water quality, pollutant sources, and alternative best management scenarios with issues related to costs and equity. The overarching aim is to develop tools and information resources that support and enlighten stakeholder input and participation and lead to better informed, science-based, and publicly acceptable management decisions regarding TMDLs. This project, in combination with other ongoing water quality monitoring and bio-economic modeling efforts, will result in a more practical approach to the development and implementation of TMDLs in Iowa. While the initial focus of the project is on waterbodies and watersheds impacted by agriculture, the approach and methods will be applicable to other TMDL issues in the state. Through the interaction with the Iowa Department of Natural Resources (IDNR), the Iowa State Water Resources Research Institute (ISWRRI) and other agencies and organizations, this project will provide valuable information needed for TMDL development and implementation both in Iowa and nationwide. Given the highly controversial nature of TMDL, research is needed now than ever to provide the tools needed to make tough and costly decisions mandated for effective watershed management.

Atmospheric nutrient (nitrogen and phosphorus; N and P) loading and transport through precipitation and dry deposition is one of the least understood and may be one of the most important pathways of nutrient transport in agricultural landscapes. Atmospheric P deposition through precipitation on a lakes surface has recently been found to contribute >30% of the annual P load, single handedly preventing eventual remediation to attain projected federal nutrient standards. The purpose of this project is to fill three essential information gaps: (I) to characterize both nitrogen and phosphorus deposition, (II) through both wet- and dry-deposition to dry- and wet-surfaces, and (III) to characterize the spatial and temporal variation of this deposition across the state of Iowa. We will measure nutrient deposition from April 1st, 2003-March 31st, 2005 at seven sites representing a range of landscape characteristics common in Iowa. Upon collection, samples will be returned to the Limnology Lab at Iowa State University for analysis. Comparisons among types of deposition measures will be made using non-parametric equivalents of ANOVA. Temporal analyses will be made graphically as well as using multivariate methods to relate deposition to storm type, source and intensity. Spatial patterns will be characterized using kriging within geostatistical (GIS) packages. This project will allow a broader understanding of the process of atmospheric nutrient transport in agricultural landscapes and a means of evaluating the role of atmospheric deposition in water quality impairment and remediation.

The use of antibiotic agents in fields other than human treatment has grown rapidly over the past few decades. Currently, the veterinary use of antibiotics accounts for approximately 40-50% of all antibiotics produced, and only 20% of that amount is employed in disease treatment, with the rest serving a sub-therapeutic role in growth promotion and disease prevention. Unfortunately, due to the poor uptake mechanisms of the treated animals, most of the antibiotics administered are excreted, unaltered, into the soil surrounding feed lots. Recently, it has been observed that microbial strains have developed antibiotic resistance as an effect of high dosages of antibiotic agents in the soil. Some effort has gone into identifying the phenomena of antibiotic resistance development around feed lots, specifically the detection of the identities of the microorganisms present and the tet-determinants responsible for the resistance. The interest of the current project lies in the detection and monitoring of the development of resistant strains as well as the specific genes responsible for the antibiotic resistance. Flow through columns (30 cm) have been packed with previously unexposed (to antibiotics) soil, as to mimic the natural conditions of the runoff water underlying feed lots. Currently, two columns are operating in a continuous manner, with one receiving a solution consisting of synthetic ground water and acetate, and the second, enriched with tetracycline. The concentrations of both acetate and tetracycline are monitored at both the entrance and exit of the columns, and profiles of these columns along their length are also monitored. Early results point out that tetracycline is being degraded upon contact with the column soil, and only about 5% of the original amount is detectable at the column exit. Most probable number (MPN) enumeration technique was used to monitor changes on the total heterotrophic population and antibiotic resistant strain populations of the two columns. PCR detection of tet-genes of the isolated resistant strains was performed but the targeted determinants were not detected in these microorganisms, suggesting the presence of tet-determinants coding for the efflux pump excretion mechanisms. Preliminary results suggest that sustained TC exposure decreases the concentrations of total heterotrophs and increases the fraction of the microorganisms that are resistant to the antibiotic. Whether discontinuing TC exposure results in the rapid loss of tet-resistance in the exposed microorganisms remains to be determined.

Impaired surface water and West Nile Virus (WNV), two issues that are critically important to Iowans, may be interrelated. High levels of nutrients and other agricultural chemicals that contaminate surface water may increase production of mosquitoes and their potential for carrying disease. Because mosquito numbers and vector efficiencies are determined by food quality during larval development, higher levels of nutrients may increase mosquito numbers. Likewise, pesticides applied to crops and gardens may have unexpected consequences upon mosquito production. Biology students at the University of Northern Iowa and I will evaluate various bodies of surface water in northeastern Iowa for their potential as mosquito developmental sites. We will estimate the risk of mosquito production for each site through on-the-ground surveys of biological, physical, and chemical attributes. We will identify sources of nutrients through land-use surveys and through remote sensing imagery based upon predictive characteristics from our on-the-ground survey. We will generate a Geographic Information System model for high-nutrient water bodies that will estimate risk of mosquito production and disease transmission. This study will provide valuable information concerning environmental impacts on impaired water quality, will provide educational opportunities for student researchers, and should result in a publication in a refereed journal.

Surface water quality is currently one of the most important environmental issues facing the state of Iowa since the ecological and recreational health of water bodies are threatened by non-point source (NPS) pollution. Many lakes are polluted because of their high concentration of nutrients, often phosphorus (P), which leads to excessive algal growth (eutrophication). To prevent eutrophication, it is necessary to prevent P from entering surface waters or to sequester (make unavailable to algae) the P that is already in the water body. Ferric (Fe3+) and ferrous (Fe2+) iron are known to react with phosphate, leading to precipitates that tie up P. The ferric iron primarily present in hematite can react with P directly, or the iron can be reduced to ferrous iron in anaerobic waters through anaerobic respiration by certain microorganisms present in soils and sediments. This ferrous iron can react with P or can be re-oxidized chemically or biologically back to ferric iron which forms P-sequestering particulate hydrous ferric oxides (HFO). Anaerobic re-oxidation of iron is facilitated by oxidants with a more positive redox potential than the ferric/ferrous couple such as the nitrate/N2 couple. When this occurs, iron oxidation also helps resolve nitrate stimulated eutrophication. An ongoing study of Iowa lakes and wetlands presents an opportunity to investigate the finding that phosphorus found in sediments can be sequestered with iron mine tailings. Specifically, the microbial chemistry involved in the sequestration of P by mixtures of P-laden soils and sediments and iron mine tailings, particularly under anaerobic conditions, will be investigated. The results will assist in formulation of pollution reduction and remediation plans for eutrophic lakes in Iowa and other locations where P is the major pollutant.

Sediment and phosphorus loading of streams are major impairments of surface water sources in Iowa. While production of perennial forages may limit sediment and phosphorus losses in precipitation run-off, sediment and phosphorus loading of streams from stream bank erosion may occur in pastures that are grazed to short sward heights by excessive numbers of cows. Further nutrient loading of streams may result from direct deposition of nutrients in manure. Because sediment and nutrient losses may be limited by maintaining an adequate forage sward height and distribution of manure may be altered by controlling animal movement with fencing or placement of alternative water sources, grazing management may be used to limit nonpoint source pollution of pastures streams. Therefore, an experiment is proposed to 1. Quantify the losses and flow of sediment and phosphorus from stream banks in pastures grazed under different stocking systems; 2. Measure the daily duration of time that cattle occupy locations in streams, along stream banks, and in riparian and upland areas in pastures grazed under different stocking systems; 3. Quantify the frequency that cattle defecate in streams, along stream banks, and in riparian and upland areas in pastures grazed under different stocking systems; and 4. Develop site-specific models of grazing management practices that optimize the quality of stream water and the profitability of pastures in Iowa. Six 30-acre smooth bromegrass pastures that have Clear Creek running through them will be stocked with 18 cow-calf pairs in three grazing management systems: continuous stocking with full access to the stream; rotational stocking (9 paddocks) with full access to the stream within each paddock and alternative water distal from the stream; and rotational (8 paddocks) with deferred (1 paddock containing the stream) stocking with limited access to the stream and alternative water distal to the stream. Paddocks grazed by rotational and deferred stocking will be managed for 50% forage removal and grazed to a 4-inch residual height, respectively. Cattle movement and fecal distribution patterns will be measured monthly on a four (equidistant perpendicular to the stream) by five (in the stream, on the stream bank, and 100, 200 or greater than 200 feet from the stream bank) grid and related to ambient temperature, and forage height and mass. Sediment and phosphorus pollution from stream bank erosion will be measured as the change in length of 5/8-inch fiberglass pins placed 3, 6, 9, and 12 feet from the streams edge in 10 locations in each pasture and the soil phosphorus concentration measured as different soil depths at the initiation of the experiment. Relationships of stream bank erosion to soil surface roughness, forage canopy cover and climatic conditions will be determined. Cow production costs and returns will be determined and used with the sediment and phosphorus losses in optimization models for water quality and economic returns. The results will provide data for the development of water quality plans that consider the benefits of improved grazing management practices and, thus, enhance both water quality and economic returns.