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Accurate simulation of agricultural management effects on N loss in tile drainage is vitally important for understanding hypoxia in the Gulf of Mexico. An experimental study was initiated in 1978 at Nashua, Iowa of the USA to study long-term effects of tillage, crop rotation, and N management practices on subsurface drainage flow and associated N losses. The Root Zone Water Quality Model (RZWQM) was applied to evaluate various management effects in several previous studies. In this study, the simulation results were further analyzed for management effects (tillage, crop rotation, and controlled drainage) on crop production and N loss in drain flow. RZWQM simulated the observed increase in N concentration in drain...
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Nitrapyrin is a nitrification inhibitor that is co-applied with N-fertilizer in agroecosystems. Over the course of one year (March 2016 to June 2017), 192 water samples from seven streams across Iowa and Illinois were analyzed for nitrapyrin, its degradate 6-chloropicolinic acid (6-CPA), and three widely used herbicides acetochlor, atrazine, and metolachlor. Additional environmental samples were collected and analyzed in spring 2017: 63 water samples from eight subsurface drains, and 33 soil samples from a field in Iowa that received direct application of nitrapyrin (only for nitrapyrin and herbicides). Nitrapyrin was detected in all seven streams (56% detection) with concentrations ranging from 4 to 1,200 ng/L;...
Summary Drainage tiles buried beneath many naturally poorly drained agricultural fields in the Midwestern U.S. are believed to “short circuit” pools of NO 3 - -laden soil water and shallow groundwater directly into streams that eventually discharge to the Mississippi River. Although much is known about the mechanisms controlling this regionally pervasive practice of artificial drainage at the field-plot scale, an integrative assessment of the effect of drainage density (i.e., the number of tile drains per unit area) on the transport of nutrients and solutes in streams at the catchment scale is lacking. In this study, we quantified the flux and hydrological pathways of agricultural NO 3 - and road-salt Cl− from catchments...
In this study, the ADAPT (Agricultural Drainage and Pesticide Transport) model was calibrated and validated for monthly flow and nitrate-N losses, for the 2000–2004 period, from two minor agricultural watersheds in Seven Mile Creek (SMC-1 and SMC-2) in south-central Minnesota. First, the model was calibrated and validated using the water quality data from the SMC-1 and again independently validated with the SMC-2 dataset. The predicted monthly flow and associated nitrate-N losses agreed reasonably with the measured trends for both calibration (r2 = 0.81 and 0.70 for flow and nitrate-N losses, respectively) and validation (r2 = 0.85 and 0.78 for flow and nitrate-N losses from SMC-1, and 0.89 and 0.78 for flow and...
A number of structural and managerial practices were evaluated to determine their environmental and economic effectiveness on animal feeding operations in the upper Maquoketa river watershed in northeast Iowa. Economic and environmental model simulations were performed over a 30-year time horizon for each of these practices using extensive data collected from the study area. Results from model simulations indicate that while most of the practices (including terraces, no till farming, contouring, and in-field contour buffers) would reduce sediment and sediment-bound nutrient losses significantly, they have very little benefit on soluble nitrogen and phosphorus losses. This is primarily because the increased infiltration...
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Nitrapyrin, a nitrification inhibitor, 6-CPA, a nitrapyrin degradate, and three co-applied herbicides (acetochlor, atrazine, and metolachlor) were measured in surface drains from eights sites in Illinois. Water samples were collected from April to June 2017. The compounds studied are applied to corn, Illinois is one of the largest corn producing states in the U.S. Water samples (1-L) were collected in amber glass bottles using a grab or depth weighted approach. Water samples were filtered (0.7 micrometers), extracted via solid phase extraction (Oasis® MAX cartridge), and analyzed (nitrapyrin and herbicides by gas chromatography with mass-spectrometry; 6-CPA by liquid chromatography tandem mass-spectrometry).
Upscaling the spatial and temporal changes in carbon (C) stocks and fluxes from sites to regions is a critical and challenging step toward improving our understanding of the dynamics of C sources and sinks over large areas. This study simulated soil organic C (SOC) dynamics within 0–100 cm depth of soils across the state of Iowa in the USA from 1972 to 2007 using the General Ensemble biogeochemical Modeling System (GEMS). The model outputs with variation coefficient were analyzed and assembled from simulation unit to the state scale based upon major land use types at annual step. Results from this study indicate that soils (within a depth of 0–100 cm) in Iowa had been a SOC source at a rate of 190 ± 380 kg C ha−1...


map background search result map search result map Nitrapyrin, 6-CPA, and herbicide concentrations in agricultural soils, subsurface drains, and corresponding streams in the Midwestern US Nitrapyrin, 6-CPA, and herbicide concentrations in subsurface drains in the Midwestern US (April 2017 to June 2017) Nitrapyrin, 6-CPA, and herbicide concentrations in subsurface drains in the Midwestern US (April 2017 to June 2017) Nitrapyrin, 6-CPA, and herbicide concentrations in agricultural soils, subsurface drains, and corresponding streams in the Midwestern US