Location: National Soil Erosion Research2018 Annual Report
Objective 1: Quantify short- and long- term impacts of drainage water management, cover crop and manure application on soil and water quality, and greenhouse gas emissions of the Eastern Corn Belt. Objective 2: Assess climate change impacts on erosion and water quality for the Eastern Corn Belt using projected climate scenarios with the WEPP and SWAT models.
1. Monitor and assess changes in soil and water quality and greenhouse gas emission under different drainage water management, cover crop and manure applications at university research farms as well as farmer fields as a part of the Long-Term Agro-ecological Research (LTAR) network for the Eastern Corn Belt. 2. Downscale global climate change scenarios for the Eastern Corn Belt and perform simulations using the Water Erosion Prediction Project (WEPP) model Soil and Water Assessment Tool (SWAT) to assess the climate change effects on erosion and water quality at the region.
Excessive transport of dissolved phosphorus (P) to surface waters directly contributes to water quality degradation, such as the eutrophication of Lake Erie and Chesapeake Bay. Phosphorus removal structures are a new technology that utilizes industrial by-products in a landscape-scale filter. Steel slag is one of the most popular P sorption materials (PSMs) due to its availability and ability to conduct water at high flow rates. However, slag must first be sieved in order to achieve this permeability, and much of the P removal ability is found in the fines. On the other hand, the fine fraction often produces excessive amounts of precipitant that can clog the filter upon drying. The potential for utilizing the slag fines in a filter design that allows for water to flow from the bottom-upward instead of the traditional top-downward was evaluated. The results appear to be promising as no clogging occurred with our pilot-scale unit, due to the flocculated precipitant being saturated in water at all times, preventing it from drying and forming a solid that could clog the filter. When tested on a small scale, this material has the potential to remove dissolved P for over 30 years. Future work is to be conducted on scaling up to the field. This research provides guidance for how to properly design P removal structures that are economical and efficient at improving water quality. Determining precise phosphorus requirements for soybean is critical for maximizing agronomic/economic efficiency and minimizing nutrient pollution. A study using sand hydroponics, as opposed to soil, in order to precisely control solution nutrient concentrations for soybean was conducted with a range in solution P from 0.01 to 0.35 mg/L, by adding the nutrients through irrigation applied several times per day. Even at the highest P concentration applied, soybean was deficient in P. There was a strong correlation between P uptake, plant biomass, leaf surface area, average pod mass, and number of leaves dropped, with solution P concentration. The more severe the P deficiency, the more leaves were dropped. Current literature reports that soybean does not show visible symptoms of P deficiency, only decreased yield. It was observed clear deficiency symptoms that proceeded rapidly: older leaves showed chlorosis near the center of the leaf, which extended outward with time, until the entire leaf turned brown and the leaf dropped. From the onset of the visible symptom, a tri-fold would drop within four days. The experiments will be repeated with higher P concentrations in order to determine the minimum mass of P uptake required for maximum pod yield. These results are useful to growers and consultants interested in properly identifying P deficiency in soybean. In laboratory experiments, extraction of Mehlich-3 P (M3-P) decreased 40% to 55% with increasing soil pH. Water-soluble P (WSP) increased with increasing pH up to pH 6–7. Mehlich-3 (M3) P and WSP should be positively correlated if M3 is to be used as an indicator of plant availability and for risk of P loss. However, they were not positively correlated except for one soil type. Thus Mehlich-3 P should be used in combination with WSP as indicators of plant availability and pollution risk. Use of M3-P alone at soil pH < 5.5 may overestimate solubility. Future research should examine the suitability of M3-P at soil pH > 7. Experimental set-ups were implemented at both Throckmorton-Purdue Agricultural Center (TPAC) and Davis-Purdue Agricultural Center (DPAC), including the implementation of cover crops (TPAC and DPAC) and manure applications (DPAC). Soils were collected before the implementation of these practices to obtain background information (Before period). In 2018, soil and plant samples were collected to assess Year 1 of this project (before planting and soybean R2 stage). In addition, after planting in 2018, suction lysimeters were installed in both TPAC and DPAC sites to sample soil water and analyze for soluble nutrients and pesticides. Research studies related to climate change and impacts on runoff, sediment loss, and chemical losses have been conducted cooperatively with graduate students, post-docs, visiting scholars, and faculty at Purdue University. These include applications of the Soil and Water Assessment Tool (SWAT) and Water Erosion Prediction Project (WEPP) models to the St. Joseph River watershed in northeastern Indiana, application of the Agricultural Policy Extender (APEX) model to the Western Lake Erie Basin, application of a linked Variable Capacity Infiltration-Water Erosion Prediction Project (VIC-WEPP) model to the Great Lakes region, and development and application of a WEPP-Water Quality model in two watersheds in the Great Lakes region. Quality checked and bias corrected future climate data sets for 2020-2100 for the Western Lake Erie Basin (16 weather stations) were developed through the efforts of a Purdue University graduate student and their committee advisors, and plans are to make these publicly available at a Purdue University Repository website following publication of the associated journal paper.
1. Limitations on the use of Mehlich-3 phosphorus extraction: impact of soil pH. Making accurate phosphorus (P) fertilizer recommendations is critical for achieving maximum agronomic and economic efficiency, as well as minimizing excess P applications that contribute to water quality degradation. Mehlich-3 (M3) is one of the most common P extractants for determining P fertilizer requirements and the potential for non-point source pollution. Understanding how soil properties impact M3 extractability can improve the ability to properly use this soil test, and one of the most important soil properties in that regard is pH. Extraction of Mehlich-3 P decreased 40% to 55% with increasing pH. Mehlich-3 P and water soluble P (WSP) should be positively correlated if M3 is to be used as an indicator of plant availability and for risk of P loss. However, they were not positively correlated except for one soil type. Therefore, ARS researchers at West Lafayette, Indiana, recommend that Mehlich-3 P should not be used alone, but in combination with WSP as indicators of plant availability and pollution risk. Further research should examine the suitability of M3-P at pH > 7. This research provides guidance for how to properly use Mehlich-3 P for crop production and water quality protection.
2. Using phosphorus sorption materials in bio-retention cells for improving water quality. Excess phosphorus (P) transported to surface waters from the landscape is a significant contributor to eutrophication and poor water quality. Bioretention cells (BRC) are an urban best management practice (BMP) that work by mitigating both water quantity and quality through slow release of runoff water and filtering of nutrients such as P. A new technique for BRCs includes use of fly-ash as a P filter material, thereby making the BRC a type of P removal structure. ARS researchers at West Lafayette, Indiana, examined the effectiveness of several BRCs that were in operation for several years. The filter media was sampled to a depth of 0.6 m and tested for different forms of P. Most of the P was captured in the upper 15 cm of the BRCs. Overall efficiency of the BRCs with fly-ash ranged from 68-75% in reducing P concentration, and 76-93% in reducing P mass (i.e. load). The appreciable measured P reduction illustrates how this BMP can serve as an effective tool at reducing dissolved P losses to surface waters through a simple modification of BRCs.
3. Assessment of phosphorus availability in soil cultivated with ruzigrass. Growing ruzigrass in crop rotations is often encouraged to improve phosphorus (P) availability to plants. However, even though soil tests indicate that soil P should be more plant available after ruzigrass cultivation, decreased yields of the crop following ruzigrass is often observed. The objective of this study was to explore how ruzigrass changed soil P forms, and compare this to measured P uptake by corn planted in soil that was previously cultivated with ruzigrass. Isothermal titration calorimetry (ITC) was also used to assess P sorption and desorption mechanisms of P onto soil. ARS researchers in West Lafayette, Indiana, showed that growing corn in soil that was previously cultivated with ruzigrass resulted in less plant uptake of soil P, even though soil extractable P (resin-P) and soil organic matter was higher compared to soils that were not previously cultivated with ruzigrass. The P fractionation test combined with plant uptake indicated that organic P bound to iron (Fe) and alumunim (Al) was non-available, and that this form of P increased from ruzigrass cultivation. The ITC technique indicated that P was less sorbed with greater strength in the ruzigrass cultivated soil, which likely decreased bioavailability to corn. The results of this study indicate that certain types of crop rotations can decrease soil P availability to the following crop. This research has a direct impact on agricultural producers and researchers interested in crop rotation effects on nutrient availability.
4. Plant stem juice: a natural and organic soil erosion control material. Many industrial by-products are used as soil amendments to improve water infiltration, soil fertility and reduce runoff and erosion. Nevertheless, some of the by-products may contain harmful residues, hence constraints in their usage. ARS researchers at West Lafayette, Indiana and cooperators in China tested plant stem juice, a natural by-product from fiber extraction, for its effectiveness in reducing soil erosion. Both corn and grape stem juices were tested under laboratory rainfall simulation. All stem juice treatments increased soil aggregate size, percent water stable aggregate, soil organic carbon, and total nitrogen but reduced runoff and soil loss. The corn stem juice was more effective in reducing soil erosion (~ 88% reduction) as compared to the grape stem juice (~ 30% reduction), probably due to its higher carbon and nutrient contents in the juice. A parallel study on the corn stem juice also showed a significant increase in the soil crust strength under controlled sand blasting, hence a potential application to reduce wind erosion and dust emission. The research opens a new avenue for industries in processing plant materials for bioenergy and fiber production that their waste stream can have soil conservation benefits.
5. Modeling studies were completed related to the effects of projected climate change on runoff, soil erosion, and pollutant losses. Changes in climate are expected over the next 80 years due to rising CO2 levels in the atmosphere, and increased precipitation, storm severity, and temperatures may all affect the occurrence and severity of runoff and erosion rates. ARS scientists with collaborators from Purdue University conducted a number of projects. These included applications of the Water Erosion Prediction Project (WEPP) model in Brazil under different land management systems; we found WEPP had acceptable performance and land use had significant effects on runoff and soil loss rates. The Soil and Water Assessment Tool (SWAT) was applied in northeastern Indiana where average annual maximum and minimum daily temperatures were projected to increase by approximately 4°C by 2099, and average annual rainfall volume was predicted to increase by approximately 8.5%. Total runoff and sediment loss were projected to increase, while no significant changes were predicted for nutrient or pesticide losses. The coupled Variable Infiltration Capacity – WEPP (VIC-WEPP) model was applied to the Great Lakes region, and results indicated that to reduce soil loss there, soil conservation efforts should focus on the fall and winter seasons to reduce the effects of increased precipitation. Understanding possible changes in erosion and pollutant losses into the future may allow conservation agency personnel and landowners to develop management strategies to minimize harmful impacts.
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Williams, M.R., Livingston, S.J., Penn, C.J., Smith, D.R., King, K.W., Huang, C. 2018. Controls of event-based nutrient transport within nested headwater agricultural watersheds of the western Lake Erie basin. Journal of Hydrology. 559:749-761.
Penn, C.J., Bowen, J.M. 2017. Design and construction of phosphorus removal structures for improving water quality. Cham, Switzerland: Springer International Publishing AG. 228 p.
Penn, C.J., Zoca, S.M. 2017. An important tool with no instruction manual: A review of gypsum use in agriculture. Advances in Agronomy. 144:1-44.
Carmeis Filho, A., Penn, C.J., Crusciol, C., Calonego, J.C. 2017. Lime and phosphogypsum impacts on soil organic matter pools in a tropical Oxisol under long-term no-till conditions. Agriculture, Ecosystems and Environment. 241:11-23.
Almeida, D.S., Penn, C.J., Roselem, C.A. 2018. Assessment of phosphorus availability in soil cultivated with ruzigrass. Geoderma. 312:64-73.
Whitaker, A.H., Penn, C.J. 2018. Total petroleum hydrocarbon degradation and BTEX leaching in soils after application of oil-base drilling mud: Impact of application rate, rainfall regime, and time. Modern Approaches in Oceanography and Petrochemical Sciences. 1(2):1-13. https://doi.org/10.32474/MAOPS.2018.01.000107.
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Penn, C.J., Rutter, E.B., Arnall, D.B., Camberato, J., Williams, M.R., Watkins, P. 2018. A discussion on Mehlich-3 phosphorus extraction from the perspective of governing chemical reactions and phases: Impact of soil pH. Agriculture. 8(7):106. https://doi.org/10.3390/agriculture8070106.
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Wang, L., Flanagan, D.C., Cherkauer, K. 2018. Climate change impacts on the nutrient losses of two watersheds in the Great Lakes region. Water. 10:442. doi:10.3390/w10040442.
Wei, X., Huang, C., Wei, N., Zhao, H., Wang, T. 2018. Reducing soil loss using surface application of stem juices. Land Degradation and Development. 29:1705-1713. doi: 10.1002/ldr.2969.
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