Insights on agricultural nitrate leaching from soil block mesocosms.

Quantifying nitrate leaching in agricultural fields is often complicated by inability to capture all water draining through a specific area. We designed and tested undisturbed soil monoliths (termed "soil block mesocosms") to achieve complete collection of drainage. Each mesocosm measures 1.

U.S. cereal rye winter cover crop growth database.

Winter cover crop performance metrics (i.e., vegetative biomass quantity and quality) affect ecosystem services provisions, but they vary widely due to differences in agronomic practices, soil properties, and climate.

Poorly drained depressions can be hotspots of nutrient leaching from agricultural soils.

Much of the US Corn Belt has been drained with subsurface tile to improve crop production, yet poorly drained depressions often still flood intermittently, suppressing crop growth. Impacts of depressions on field-scale nutrient leaching are unclear. Poor drainage might promote denitrification and physicochemical retention of phosphorus (P), but ample availability of water and nutrients might exacerbate nutrient leaching from cropped depressions.

Influence of no-till and a winter rye cover crop on nitrate losses from tile-drained row-crop agriculture in Iowa.

Artificial subsurface drainage is necessary to maintain agricultural production in the soils and climate of north-central Iowa. However, it can result in adverse environmental impacts, because it intercepts and diverts some water and soluble NO -N directly to streams. We investigated the impact of no-till and a winter rye cover crop (Secale cereale L.

Midwestern cropping system effects on drainage water quality and crop yields.

Grain producers are challenged to maximize crop production while utilizing nutrients efficiently and minimizing negative impacts on water quality. There is a particular concern about nutrient export to the Gulf of Mexico via loss from subsurface drainage systems. The objective of this study was to investigate the effects of crop rotation, tillage, crop residue removal, swine manure applications, and cereal rye (Secale cereale L.

High-frequency, in situ sampling of field woodchip bioreactors reveals sources of sampling error and hydraulic inefficiencies.

Woodchip bioreactors are a practical, low-cost technology for reducing nitrate (NO) loads discharged from agriculture. Traditional methods of quantifying their performance in the field mostly rely on low-frequency, time-based (weekly to monthly sampling interval) or flow-weighted sample collection at the inlet and outlet, creating uncertainty in their performance and design by providing incomplete information on flow and water chemistry. To address this uncertainty, two field bioreactors were monitored in the US and New Zealand using high-frequency, multipoint sampling for in situ monitoring of NO-N concentrations.

Catchment-scale Phosphorus Export through Surface and Drainage Pathways.

The site-specific nature of P fate and transport in drained areas exemplifies the need for additional data to guide implementation of conservation practices at the catchment scale. Total P (TP), dissolved reactive P (DRP), and total suspended solids (TSS) were monitored at five sites-two streams, two tile outlets, and a grassed waterway-in three agricultural subwatersheds (221.2-822.

Drying-Rewetting Cycles Affect Nitrate Removal Rates in Woodchip Bioreactors.

Woodchip bioreactors are widely used to control nitrogen export from agriculture using denitrification. There is abundant evidence that drying-rewetting (DRW) cycles can promote enhanced metabolic rates in soils. A 287-d experiment investigated the effects of weekly DRW cycles on nitrate (NO) removal in woodchip columns in the laboratory receiving constant flow of nitrated water.

Prairie strips improve biodiversity and the delivery of multiple ecosystem services from corn-soybean croplands.

Loss of biodiversity and degradation of ecosystem services from agricultural lands remain important challenges in the United States despite decades of spending on natural resource management. To date, conservation investment has emphasized engineering practices or vegetative strategies centered on monocultural plantings of nonnative plants, largely excluding native species from cropland. In a catchment-scale experiment, we quantified the multiple effects of integrating strips of native prairie species amid corn and soybean crops, with prairie strips arranged to arrest run-off on slopes.

Maximum soil organic carbon storage in Midwest U.S. cropping systems when crops are optimally nitrogen-fertilized.

Nitrogen fertilization is critical to optimize short-term crop yield, but its long-term effect on soil organic C (SOC) is uncertain. Here, we clarify the impact of N fertilization on SOC in typical maize-based (Zea mays L.) Midwest U.

Subsurface Drainage Nitrate and Total Reactive Phosphorus Losses in Bioenergy-Based Prairies and Corn Systems.

We compare subsurface-drainage NO-N and total reactive phosphorus (TRP) concentrations and yields of select bioenergy cropping systems and their rotational phases. Cropping systems evaluated were grain-harvested corn-soybean rotations, grain- and stover-harvested continuous corn systems with and without a cover crop, and annually harvested reconstructed prairies with and without the addition of N fertilizer in an Iowa field. Drainage was monitored when soils were unfrozen during 2010 through 2013.

Comparing nitrate sink strength in perennial filter strips at toeslopes of cropland watersheds.

Integration of perennial filter strips (PFS) into the toeslopes of agricultural watersheds may decrease downstream nitrate (NO) losses. However, long-term NO removal depends on the relative importance of several NO sinks in the PFS. Plant biomass and labile soil organic matter (SOM) are temporary NO sinks, while stable SOM is a long-term, but potentially finite, NO sink.

Effects of vegetation cover of natural grassland on runoff and sediment yield in loess hilly region of China.

Background: The effects of vegetation cover (VC) on runoff and sediment yield were investigated from rainfall simulation experiments in the Loess Plateau of China. Five VCs from 0% to 80% and three different rainfall intensities (I₂.₀, ₁.

Impact of system management on vegetative treatment system effluent concentrations.

Beef feedlots of all sizes are looking for more cost-effective solutions for managing feedlot runoff. Vegetative treatment systems are one potential option, but require performance evaluation for use on concentrated animal feeding operations. The performance of six vegetative treatment systems on open beef feedlots throughout Iowa was monitored from 2006 through 2009.

Sediment removal by prairie filter strips in row-cropped ephemeral watersheds.

Twelve small watersheds in central Iowa were used to evaluate the effectiveness of prairie filter strips (PFS) in trapping sediment from agricultural runoff. Four treatments with PFS of different size and location (100% rowcrop, 10% PFS of total watershed area at footslope, 10% PFS at footslope and in contour strips, 20% PFS at footslope and in contour strips) arranged in a balanced incomplete block design were seeded in July 2007. All watersheds were in bromegrass ( L.

Simulating nitrate-nitrogen concentration from a subsurface drainage system in response to nitrogen application rates using RZWQM2.

Computer models have been widely used to evaluate the impact of agronomic management on nitrogen (N) dynamics in subsurface drained fields. However, they have not been evaluated as to their ability to capture the variability of nitrate-nitrogen (NO(3)-N) concentration in subsurface drainage at a wide range of N application rates due to possible errors in the simulation of other system components. The objective of this study was to evaluate the performance of Root Zone Water Quality Model2 (RZWQM2) in simulating the response of NO(3)-N concentration in subsurface drainage to N application rate.

Nitrate-nitrogen losses through subsurface drainage under various agricultural land covers.

Nitrate-nitrogen (NO₃-N) loading to surface water bodies from subsurface drainage is an environmental concern in the midwestern United States. The objective of this study was to investigate the effect of various land covers on NO₃-N loss through subsurface drainage. Land-cover treatments included (i) conventional corn ( L.

Modeling phosphorus transport in an agricultural watershed using the WEPP model.

The Water Erosion Prediction Project (WEPP) model has been tested for its ability to predict soil erosion, runoff, and sediment delivery over a wide range of conditions and scales for both hillslopes and watersheds. Since its release in 1995, there has been considerable interest in adding a chemical transport element to it. Total phosphorus (TP) loss at the watershed outlet was simulated as the product of TP in the soil, amount of sediment at the watershed outlet, and an enrichment ratio (ER) factor.

Perennial filter strips reduce nitrate levels in soil and shallow groundwater after grassland-to-cropland conversion.

Many croplands planted to perennial grasses under the Conservation Reserve Program are being returned to crop production, and with potential consequences for water quality. The objective of this study was to quantify the impact of grassland-to-cropland conversion on nitrate-nitrogen (NO3-N) concentrations in soil and shallow groundwater and to assess the potential for perennial filter strips (PFS) to mitigate increases in NO3-N levels. The study, conducted at the Neal Smith National Wildlife Refuge (NSNWR) in central Iowa, consisted of a balanced incomplete block design with 12 watersheds and four watershed-scale treatments having different proportions and topographic positions of PFS planted in native prairie grasses: 100% rowcrop, 10% PFS (toeslope position), 10% PFS (distributed on toe and as contour strips), and 20 PFS (distributed on toe and as contour strips).