Midwest Corn Belt Research Articles

Conservation tillage or plastic film mulching? A comprehensive global meta-analysis based on maize yield and nitrogen use efficiency

Rain-fed agriculture is an important part of the global agriculture system and plays a vital role in ensuring food security. Conservation tillage (CT) is widely used in USA maize cultivation in the Mid-west Corn Belt. Meanwhile, Chinese farmers' adoption of CT is limited and plastic film mulching (PM) is widely developed to increase maize yield in northern China. This paper compared the yield and nitrogen use efficiency (NUE) between CT and PM, and analyzed the reasons for the differences in the choice of maize cultivation practice. We collected 767 observations for CT and 217 observations for PM and analyzed how these two tillage practices affected yield. For NUE, there were 66 and 56 observations, respectively. The meta-analysis showed that PM significantly increased maize yield by 36% and NUE by 34% compared with the control, and CT significantly decreased maize yield by 5% and NUE by 15%. The effects of PM on maize yield were mainly determined by growing season precipitation (GSP) and temperature (GST). The yield response ratio was also influenced by the type of plastic film, mulching cycle, pH, soil saturated hydraulic conductivity, and soil bulk density. The negative effects of CT on yield could be alleviated under good hydrothermal conditions and with straw mulching. The yield response ratio was also affected by soil texture and N application rate. In conclusion, PM should be applied under limited hydrothermal conditions (GSP < 650 mm or GST < 23 °C), and CT was conducive to higher maize yield under good hydrothermal conditions (GSP > 650 mm or GST > 23 °C) . Besides, the average farm size was positively correlated with the CT total areas.

Soil hydrologic grouping guide which soil and weather properties best estimate corn nitrogen need

AbstractNitrogen fertilizer recommendations in corn (Zea mays L.) that match the economically optimal nitrogen fertilizer rate (EONR) are imperative for profitability and minimizing environmental degradation. However, the amount of soil N available for the crop depends on soil and weather factors, making it difficult to know the EONR from year‐to‐year and from field‐to‐field. Our objective was to explore, within the framework of hydrologic soil groups and drainage classifications (HGDC), which site‐specific soil and weather properties best estimated corn N needs (i.e., EONR) for two application timings (at‐planting and side‐dress). Included in this investigation was a validation step using an independent dataset. Forty‐nine N response trials conducted across the U.S. Midwest Corn Belt over three growing seasons (2014–2016) were used for recommendation model development, and 181 independent site‐years were used for validation. For HGDC models, soil organic matter (SOM), clay content, and evenness of rainfall distribution before side‐dress N application were the properties generally most helpful in predicting EONR. Using the validation data, model recommendations were within 34 kg N ha–1 of EONR for 37 and 42% of the sites with a root mean square error (RMSE) of 70 and 68 kg N ha–1 for at‐planting and side‐dress applications, respectively. Compared to state‐specific recommendations, sites needing &lt;100 kg N ha–1 or no N were better estimated with HGDC models. In contrast, for sites where EONR was &gt;150 kg N ha–1, HGDC models underestimated N needs compared to state specific. These results show HGDC groupings could aid in developing tools for N fertilizer recommendations.

Future Summer Drying in the U.S. Corn Belt and the Role of Midlatitude Storm Tracks

AbstractDuring the summer, the Midwest United States, which covers the main US corn belt, has a net loss of surface water as evapotranspiration exceeds precipitation. The net moisture gain into the atmosphere is transported out of the region to northern high latitudes through transient eddy moisture fluxes. How this process may change in the future is not entirely clear despite the fact that the corn belt region is responsible for a large portion of the global supply of corn and soybeans. We find that increased CO2 and the associated warming increases evapotranspiration. while precipitation reduces in the region leading to further reduction in precipitation minus evaporation (P-E) in the future. At the same time, the poleward transient moisture flux increases leading to enhanced atmospheric moistures export from the corn belt region. However, storm track intensity is generally weakened in the summer due to reduced north-south temperature gradient associated with amplified warming in the midlatitudes. The intensified transient eddy moisture transport as storm track weakens can be reconciled by the stronger mean moisture gradient in the future. This is found to be caused by the climatological low-level jet transporting more moisture into the Great Plains region due to the thermodynamic mechanism under warmer conditions. Our results, for the first time, show that in the future, the US Midwest corn belt will experience more hydrological stress due to intensified transient eddy moisture export leading to drier soils in the region.

Corn nitrogen rate recommendation tools’ performance across eight US midwest corn belt states

AbstractDetermining which corn (Zea mays L.) N fertilizer rate recommendation tools best predict crop N need would be valuable for maximizing profits and minimizing environmental consequences. Simultaneous comparisons of multiple tools across various environmental conditions have been limited. The objectives of this research were to evaluate the performance of publicly‐available N fertilizer recommendation tools across diverse soil and weather conditions for: (i) prescribing N rates for planting and split‐fertilizer applications, and (ii) economic and environmental effects. Corn N‐response trials using standardized methods were conducted at 49 sites, spanning eight US Midwest states and three growing seasons. Nitrogen applications included eight rates in 45 kg N ha−1 increments all at‐planting and matching rates with 45 kg N ha−1 at‐planting plus at the V9 development stage. Tool performances were compared to the economically optimal N rate (EONR). Over this large geographic region, only 10 of 31 recommendation tools (mainly soil nitrate tests) produced N rate recommendations that weakly correlated to EONR (P ≤ .10; r2 ≤ .20). With other metrics of performance, the Maximum Return to N (MRTN) soil nitrate tests, and canopy reflectance sensing came close to matching EONR. Economically, all tools but the Maize‐N crop growth model had similar returns compared to EONR. Environmentally, yield goal based tools resulted in the highest environmental costs. Results show that no tool was universally reliable over this study's diverse growing environments, suggesting that additional tool development is needed to better represent N inputs and crop utilization at a larger regional level.

Intensification of Midwestern Agriculture as a Regional Climate Modifier and Atmospheric Boundary Layer Moisture Source

Agricultural land use changes have likely played an important role in modifying local and regional climate factors. According to a recent study, summers in the Midwest were significantly cooler and wetter due to the dramatic increases in production of corn and soybeans caused by an intensification of agricultural practices (Alter et al. 2018). In this context, this study examines regional changes manifested in multiple climate variables and directly quantifies the magnitude of potential moisture contributions from Midwest corn and soybean agriculture. Meteorological data were collected for daily minimum, maximum, and dewpoint temperatures over a sixty-one-year study period from fifty-nine National Weather Service first-order stations and cooperative network stations. Regional growing season climatology for two study regions that focused on the rain-fed Midwest Corn Belt and the southern United States extending to the Gulf Coast was analyzed. Further, vapor pressure deficit was calculated to ascertain any regional changes. Field surveys of corn and soybean crop transpiration were used in a multivariate model to estimate lower atmospheric moisture contributions at midday during peak season directly from intensified rain-fed agriculture. Findings indicate an increase in regional dewpoint, associated with elevated nocturnal minimums and suppression of both daily maximum and vapor pressure deficit, concentrated in the Midwest Corn Belt, which was not evident within the South. The estimation results of the atmospheric moisture contributions from the Corn Belt confirm the intensification of Midwestern agriculture as a regional climate modifier. Key Words: agriculture, dewpoint, energy balance, humidity, regional climate.

Active‐Optical Reflectance Sensing Corn Algorithms Evaluated over the United States Midwest Corn Belt

Core Ideas Active‐optical reflectance sensor algorithms perform poorly outside the area for which they were originally developed. The red edge waveband is more sensitive to N stress than the red waveband. Some active‐optical reflectance algorithms are dependent on the sensor for which they were developed. Uncertainty exists with corn (Zea mays L.) N management due to year‐to‐year variation in crop N need, soil N supply, and N loss from leaching, volatilization, and denitrification. Active‐optical reflectance sensing (AORS) has proven effective in some fields for generating N fertilizer recommendations that improve N use efficiency, but locally derived (e.g., within a US state) AORS algorithms have not been tested simultaneously across a broad region. The objective of this research was to evaluate locally developed AORS algorithms across the US Midwest Corn Belt region for making in‐season corn N recommendations. Forty‐nine N response trials were conducted across eight states and three growing seasons. Reflectance measurements were collected and sidedress N rates (45–270 kg N ha−1 on 45 kg ha−1 increments) applied at approximately V9 corn development stage. Nitrogen recommendation rates from AORS algorithms were compared with the end‐of‐season calculated economic optimal N rate (EONR). No algorithm was within 34 kg N ha−1 of EONR &gt; 50% of the time. Average recommendations differed from EONR 81 to 147 kg N ha−1 with no N applied at planting and 74 to 118 kg N ha−1 with 45 kg of N ha−1 at planting, indicating algorithms performed worse with no N applied at planting. With some algorithms, utilizing red edge instead of the red reflectance improved N recommendations. Results demonstrate AORS algorithms developed under a particular set of conditions may not, at least without modification, perform very well in regions outside those within which they were developed.

Canopy sensing for corn nitrogen recommendations: Does it work?

In conjunction with canopy sensor reflectance measurements, a canopy sensor algorithm is used to formulate a nitrogen fertilizer recommendation. One such algorithm is the University of Missouri corn canopy sensor algorithm (ALGMU). The purpose of this study was to (1) evaluate the ability of the ALGMU to estimate the economical optimal N rates (EONR) across the U.S. Midwest Corn Belt and (2) improve the ALGMU performance using site‐specific soil and weather information. Earn 0.5 CEUs in Nutrient Management by reading this article and taking the quiz at www.certifiedcropadviser.org/education/classroom/classes/628.

An amphibian with a contracting range is not more vulnerable to pesticides in outdoor experimental communities than common species.

In areas with heavy pesticide use, it is easy to attribute population declines to environmental contamination. The Blanchard's cricket frogs (Acris blanchardi) is an amphibian experiencing declines and range contractions across its distribution in the Midwest Corn Belt (USA). Experimental studies suggest that cricket frogs are sensitive to pesticides, but there are few studies examining this species' susceptibility to contaminants in realistic environments or comparing relative impacts with other anuran species. I reared 3 summer breeding anurans in outdoor mesocosms posthatching through metamorphosis to examine the effects of 2 insecticides (imidacloprid and carbaryl) and 1 herbicide (glyphosate with polyoxyethylene tallow amine) on larval development and metamorphosis. Cricket frogs were positively affected by insecticide exposure, likely a result of changes in the food web that increased food abundance. However, metamorphosis of green frogs (Lithobates clamitans) and gray tree frogs (Hyla chrysoscelis) appeared unaffected by pesticide exposure. The results of the present study suggest that the impacts of pesticides alone are unlikely to have population-level impacts for the anurans examined. Environ Toxicol Chem 2018;37:2699-2704. © 2018 SETAC.

Soil and Water Assessment Tool model predictions of annual maximum pesticide concentrations in high vulnerability watersheds.

Recent national regulatory assessments of potential pesticide exposure of threatened and endangered species in aquatic habitats have led to increased need for watershed-scale predictions of pesticide concentrations in flowing water bodies. This study was conducted to assess the ability of the uncalibrated Soil and Water Assessment Tool (SWAT) to predict annual maximum pesticide concentrations in the flowing water bodies of highly vulnerable small- to medium-sized watersheds. The SWAT was applied to 27 watersheds, largely within the midwest corn belt of the United States, ranging from 20 to 386 km2 , and evaluated using consistent input data sets and an uncalibrated parameterization approach. The watersheds were selected from the Atrazine Ecological Exposure Monitoring Program and the Heidelberg Tributary Loading Program, both of which contain high temporal resolution atrazine sampling data from watersheds with exceptionally high vulnerability to atrazine exposure. The model performance was assessed based upon predictions of annual maximum atrazine concentrations in 1-d and 60-d durations, predictions critical in pesticide-threatened and endangered species risk assessments when evaluating potential acute and chronic exposure to aquatic organisms. The simulation results showed that for nearly half of the watersheds simulated, the uncalibrated SWAT model was able to predict annual maximum pesticide concentrations within a narrow range of uncertainty resulting from atrazine application timing patterns. An uncalibrated model's predictive performance is essential for the assessment of pesticide exposure in flowing water bodies, the majority of which have insufficient monitoring data for direct calibration, even in data-rich countries. In situations in which SWAT over- or underpredicted the annual maximum concentrations, the magnitude of the over- or underprediction was commonly less than a factor of 2, indicating that the model and uncalibrated parameterization approach provide a capable method for predicting the aquatic exposure required to support pesticide regulatory decision making. Integr Environ Assess Manag 2018;14:358-368. © 2017 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Where is the USA Corn Belt, and how is it changing?

The “Corn Belt” is a commonly used term, but often referenced as a vaguely defined region in the Midwest USA. A few key studies have delineated synoptic maps of the Corn Belt boundaries going back to the early 20th century, but a modern flexible and accessible framework for mapping the Corn Belt in space and time is needed. New tools provide reference maps for the Corn Belt in the 21st century and the ability to quantify space-time changes in corn cropping patterns. The Landuse and Agricultural Management Practices web-Service (LAMPS) was used to estimate the average corn (maize, Zea mays L.) area in each county of the contiguous 48 USA states for the years 2010–2016. LAMPS provides a modified areal Fraction of corn (Fc) used to map the Corn Belt at three intensity levels, for example. The resulting patterns illustrate a mostly contiguous Midwest Corn Belt surrounded by more scattered regions, including southern and eastern regions. We also mapped irrigated areas and temporal changes in Fc. Mapped patterns have the potential to help researchers study issues related to food, feed, biofuel, and water security.

Recent changes in county-level corn yield variability in the United States from observations and crop models

The United States is responsible for 35% and 60% of global corn supply and exports. Enhanced supply stability through a reduction in the year-to-year variability of US corn yield would greatly benefit global food security. Important in this regard is to understand how corn yield variability has evolved geographically in the history and how it relates to climatic and non-climatic factors. Results showed that year-to-year variation of US corn yield has decreased significantly during 1980–2010, mainly in Midwest Corn Belt, Nebraska and western arid regions. Despite the country-scale decreasing variability, corn yield variability exhibited an increasing trend in South Dakota, Texas and Southeast growing regions, indicating the importance of considering spatial scales in estimating yield variability. The observed pattern is partly reproduced by process-based crop models, simulating larger areas experiencing increasing variability and underestimating the magnitude of decreasing variability. And 3 out of 11 models even produced a differing sign of change from observations. Hence, statistical model which produces closer agreement with observations is used to explore the contribution of climatic and non-climatic factors to the changes in yield variability. It is found that climate variability dominate the change trends of corn yield variability in the Midwest Corn Belt, while the ability of climate variability in controlling yield variability is low in southeastern and western arid regions. Irrigation has largely reduced the corn yield variability in regions (e.g. Nebraska) where separate estimates of irrigated and rain-fed corn yield exist, demonstrating the importance of non-climatic factors in governing the changes in corn yield variability. The results highlight the distinct spatial patterns of corn yield variability change as well as its influencing factors at the county scale. I also caution the use of process-based crop models, which have substantially underestimated the change trend of corn yield variability, in projecting its future changes.

Evidence for a weakening strength of temperature-corn yield relation in the United States during 1980–2010

Temperature is known to be correlated with crop yields, causing reduction of crop yield with climate warming without adaptations or CO2 fertilization effects. The historical temperature-crop yield relation has often been used for informing future changes. This relationship, however, may change over time following alternations in other environmental factors. Results show that the strength of the relationship between the interannual variability of growing season temperature and corn yield (RGST_CY) has declined in the United States between 1980 and 2010 with a loss in the statistical significance. The regression slope which represents the anomalies in corn yield that occur in association with 1 degree temperature anomaly has decreased significantly from −6.9%/K of the first half period to −2.4%/K–−3.5%/K of the second half period. This implies that projected corn yield reduction will be overestimated by a fact of 2 in a given warming scenario, if the corn-temperature relation is derived from the earlier historical period. Changes in RGST_CY are mainly observed in Midwest Corn Belt and central High Plains, but are partly reproduced by 11 process-based crop models. In Midwest rain-fed systems, the decrease of negative temperature effects coincides with an increase in water availability by precipitation. In irrigated areas where water stress is minimized, the decline of beneficial temperature effects is significantly related to the increase in extreme hot days. The results indicate that an extrapolation of historical yield response to temperature may bias the assessment of agriculture vulnerability to climate change. Efforts to reduce climate impacts on agriculture should pay attention not only to climate change, but also to changes in climate-crop yield relations. There are some caveats that should be acknowledged as the analysis is restricted to the changes in the linear relation between growing season mean temperature and corn yield for the specific study period.

Cleaning up nitrogen on farmlands

A dead zone forms in the deep waters of the Gulf of Mexico every summer. This low-oxygen, or hypoxic, area can stretch for 20,000 km2 some years, with significant consequences for the Gulf’s ecosystems and economy. Hypoxia puts the multibillion-dollar tourism and fishing industries of the Gulf states at risk, but the problem starts far to the north. The Gulf dead zone feeds on the runoff of nutrients, particularly nitrogen fertilizers, from farms in the Midwest Corn Belt whose rivers and streams feed the Mississippi and Atchafalaya Rivers. When these nutrients reach the Gulf’s waters, they trigger explosive growth of algae. Eventually, these algae die and aerobic microbes feast on them and on other organic matter, consuming large amounts of oxygen from the water in the process. When levels of dissolved oxygen fall below 2 mg/L, creatures such as shrimp that can crawl or swim vacate the area, leaving little

Impact of cover crop on soil carbon accrual in topographically diverse terrain

Farmers must consider real-world problems and variability to maximize yields and minimize environmental impacts when using cover crops in corn (Zea mays L.)-based cropping systems. Much of the variability encountered by farmers of the Midwest Corn Belt is due to the topographical diversity of the undulating landscape. The objectives of this study are to explore the effects of cover crops on soil organic carbon (C), both total organic C and its labile form, particulate organic C (POC), and on water retention at contrasting topographies (summit, slope, and depression). A cereal rye (Secale cereal L.) cover crop was established in the fall of 2011 at two experimental sites. At each site, the experimental design was a split-split plot with whole plot factor, topographical position, in a randomized complete block design with two replications. Topographical position affected all studied plant and soil characteristics, including aboveground plant biomass, rye residue decomposition, POC, total soil C, and soil water retention. Across all topographical positions, rye residue decomposition was ~5% greater in the treatment with than without cover crop. In slopes and summits, the POC in the treatment with cover crop was significantly (~0.7 mg g−1 soil [~700 ppm]) greater than in the treatment without the cover crop; however, the difference was not statistically significant in depressions. The cover crop effect on both total organic C and soil water retention levels was not statistically significant. The study points to potential interactions between topography and C sequestration benefits of cover crops; however, longer experimental times are needed to detect significant differences in soil total C and water retention measurements.

Multistressor predictive models of invertebrate condition in the Corn Belt, USA

AbstractUnderstanding the complex relations between multiple environmental stressors and ecological conditions in streams can help guide resource-management decisions. During 14 weeks in spring/summer 2013, personnel from the US Geological Survey and the US Environmental Protection Agency sampled 98 wadeable streams across the Midwest Corn Belt region of the USA for water and sediment quality, physical and habitat characteristics, and ecological communities. We used these data to develop independent predictive disturbance models for 3 macroinvertebrate metrics and a multimetric index. We developed the models based on boosted regression trees (BRT) for 3 stressor categories, land use/land cover (geographic information system [GIS]), all in-stream stressors combined (nutrients, habitat, and contaminants), and for GIS plus in-stream stressors. The GIS plus in-stream stressor models had the best overall performance with an average cross-validation R2 across all models of 0.41. The models were generally consis...

Grassland and Wheat Loss Affected by Corn and Soybean Expansion in the Midwest Corn Belt Region, 2006–2013

Increases in agricultural commodity price triggered by ethanol production and other socioeconomic conditions have dramatically affected land uses and agronomic practices in the U.S. This study used crop-specific land cover data from the U.S. Department of Agriculture (USDA) to analyze agricultural expansion and crop rotation pattern from 2006 to 2013 in the Midwest Corn Belt (MWCB): nine states including Illinois, Indiana, Iowa, Kansas, Minnesota, Missouri, Nebraska, Ohio, and South Dakota. We identified a total of 3.9 million acres’ grassland loss between 2007 and 2012. The net loss of grassland occurred mainly along the western MWCB, an area with competing demand for limited water supply. Net conversion of grassland to corn or soybean is likely the result of a resumption of cropping on lands previously enrolled under the USDA Conservation Reserve Program (CRP), as well as expansion beyond CRP lands. Wheat, small grains, and other crops were also impacted by corn and soybean expansion. The amount of corn planted on corn increased by 23% between 2006 and 2013, whereas the amount of continuous soybean cropping fluctuated over time.

Cover Image, Volume 10, Issue 6

The cover image, by Maria Cristina Negri et al., is based on the Modeling and Analysis The economics of growing shrub willow as a bioenergy buffer on agricultural fields: A case study in the Midwest Corn Belt, DOI: 10.1002/bbb.1679. image

Kriging Models Predicting Atrazine Concentrations in Surface Water Draining Agricultural Watersheds

The performance of kriging methods in predicting maximum m-day (m = 1, 7, 14, or 30) rolling averages of atrazine concentrations in 42 site-years of Midwest Corn Belt watersheds under two systematic sampling designs (sampling every 7 or 14 d) was examined. Daily atrazine monitoring data obtained from the Atrazine Ecological Monitoring Program in the Corn Belt region (2009-2014) were used in the evaluation. Both ordinary and universal kriging methods were considered, with the covariate for universal kriging derived from the deterministic Pesticide Root Zone Model (PRZM). For the maximum 1-d rolling averages, prediction did not differ among methods. For rolling averages of longer duration (m > 1), predictions obtained by linear interpolation on a logarithmic scale were better (up to 15% lower for 7-d sampling and 22% lower for 14-d sampling in terms of the relative root mean squared prediction error) than those obtained by linear interpolation on the original linear scale and also less variable. For kriging methods, empirical semivariograms of daily atrazine time series suggest a negligible noise process, supported by replicate analysis of selected field samples; piecewise linear semivariogram models were found to perform best for predicting sampled data. We demonstrate that kriging prediction intervals offer close to nominal coverage for unsampled values.

The economics of growing shrub willow as a bioenergy buffer on agricultural fields: A case study in the Midwest Corn Belt

AbstractLandscape design has been embraced as a promising approach to holistically balance multiple goals related to environmental and resource management processes to meet future provisioning and regulating ecosystem services needs. In the agricultural context, growing bioenergy crops in specific landscape positions instead of dedicated fields has the potential to improve their sustainability, provide ecosystem services, and minimize competition with other land uses. However, growing bioenergy crops in sub‐productive or environmentally vulnerable parts of a field implies more complex logistics as small amounts of biomass are generated in a distributed way across the landscape. We present a novel assessment of the differences in production and logistic costs between business as usual (BAU, dedicated fields), and distributed landscape production of shrub, or short‐rotation willow for bioenergy within a US Midwestern landscape. Our findings show that regardless of the mode of cropping, BAU or landscape design, growing shrub willows is unlikely to provide positive revenues (−$67 to –$303 ha−1 yr−1 at a biomass price of $46.30 Mgwet−1) because of high land rental costs in this agricultural region. However, when translated into a practice cost per unit of N removed at the watershed scale (range: $1.8–37.0 kg N−1 yr−1), the net costs are comparable to other conservation practices. The projected opportunity cost of growing willows instead of corn on underproductive areas varied between –$14 and $49 Mgwet−1. This highlights the potential for willows to be a cost effective choice depending on the intra‐field grain productivity, biomass price and desirable concurrent ecosystem services. © 2016 The Authors. Biofuels, Bioproducts and Biorefining published by Society of Chemical Industry and John Wiley &amp; Sons, Ltd.

Assessment of plant availability and environmental risk of biosolids-phosphorus in a U.S. Midwest Corn-Belt Soil

A field experiment was conducted from 2005 to 2008 in Fulton County, Western Illinois with biosolids from conventional wastewater treatment applied as corn fertilizer in a series of P rates (0, 163, 325, 488, 650 kg P ha−1) along with commercial P fertilizer - triple superphosphate P (TSP) as reference to assess biosolids-P plant availability and potential loss to waterbodies through runoff. Air-dried biosolids and TSP were incorporated into surface soil at end of 2005, and corn (Zea mays) was planted for three consecutive years (2006–2008). Concentrations of soil extractable P except for Mehlich-3 P were always lower in the biosolids than TSP treatments at the same P rates. The soil potentially available P in water extractable P (WEP) and Olsen P derived from biosolids-P estimated by the exponential depletion model was 2–4% and 15–24% of total P in the applied biosolids, respectively. The residence time of biosolids-induced WEP and Olsen P in Midwest soil under annual corn cropping was 5 and 2 years, respectively. Corn tissue analysis showed lower increase in P concentration by biosolids-P than TSP. The elevation rate of soluble reactive P (SRP) concentration in simulated runoff was less by biosolids than TSP. Based on the data in this study, the plant availability and environmental risk of biosolids-P are lower than those of TSP in the Midwest soil, thus use of biosolids as P nutrient for corn would not cause a major impairment to water sources even P applied through biosolids was not completely used by annual crop.