Subsurface Drainage Water Quality Research Articles

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.) cover crops on nitrate-N (NO3 -N) and total reactive phosphorus (TRP) loss via subsurface drainage. The study was evaluated from 2008 through 2015 using 36 0.4-ha plots outfitted with a subsurface drainage water quality monitoring system. Results showed that when swine manure was applied before both corn (Zea mays L.) and soybean [Glycine max (L.) Merr.], drainage water had significantly higher 8-yr-average flow-weighted NO3 -N concentrations compared with swine manure applied before corn only in a corn-soybean rotation. The lowest NO3 -N loss was 15.2kg N ha-1 yr-1 from a no-till corn-soybean treatment with rye cover crop and spring application of urea-ammonium nitrate (UAN) to corn. The highest NO3 -N loss was 29.5kg N ha-1 yr-1 from swine manure applied to both corn and soybean. A rye cover crop reduced NO3 -N loss, whereas tillage and residue management had little impact on NO3 -N loss. Losses of TRP averaged<32g P ha-1 yr-1 from all treatments. Corn yield was negatively affected by both no-till management and cereal rye cover crops. Results showed that cropping management affected N leaching but impacts on P leaching were minimal.

Surface and Subsurface Phosphorus Discharge from a Clay Soil in a Nine-Year Study Comparing No-Till and Plowing.

No-till as a water protection measure is highly efficient in controlling erosion and particulate P (PP) loss but tends to increase dissolved reactive P (DRP) concentrations in runoff water. In a 9-yr field study on a clay soil in Southwest Finland, the effects of no-till and autumn plowing on surface runoff and subsurface drainage water quality were compared. The site had a 2% slope and was under spring cereal cropping, with approximately replacement fertilizer P rates. Vertical stratification of soil-test P that had developed during a preceding 6-yr grass ley was undone by plowing but continued to develop under no-till. During the 9-yr study period, no-till soil had 27% lower cumulative total P losses than plowed soil (10.0 vs. 13.7 kg total P ha). Concentrations and losses of PP were clearly lower under no-till than under plowing (5.6 vs. 12.3 kg PP ha), but DRP loss showed the opposite trend (4.3 vs. 1.4 kg DRP ha). There was an increasing trend in subsurface drainflow DRP concentration under no-till, possibly because of development of a conductive pore structure from soil surface to drain depth. The potential benefit of no-till in water protection depends on how much of the PP transported to water is transformed into a bioavailable form and used by aquatic organisms. The beneficial effect of no-till in controlling P-induced eutrophication at the study site would only be realized if the bioavailable share of PP exceeds 43%. Otherwise, no-till would not be an efficient eutrophication control measure at this site.

Impacts of nitrogen application timing and cover crop inclusion on subsurface drainage water quality

Significant reductions in nitrogen loading from sub-surface drainage fields of the Upper Mississippi River Basin to the Gulf of Mexico will most likely be achieved from the mass adoption of nutrient loss reduction strategies at a watershed scale. Few studies have quantified the efficacy of cover crops to reduce NO3-N loading in nitrogen fertilizer management systems, where the dominant portion of the N rate is applied in the spring or fall, both of which are common practices in the Upper Mississippi River Basin. In this experiment we quantified the impact of N application timing and cover crop inclusion on NO3-N loss (leaching) from agricultural sub-surface drainage within five nitrogen management scenarios: a zero control, applying the dominant portion of the N rate in the spring, applying the dominant portion of the N rate in the fall, augmenting the a spring and Fall N application system with cover crop. Each of the five nitrogen management scenarios was replicated three times on individually monitored sub-surface drainage plots established in Lexington, IL. During the experiment, a cereal rye (Secale cereal L.) and radish (Raphanus sativus L.) blend was interseeded within both corn (Zea mays L.) and soybean (Glycine max L.). Fertilizer N application timing did not affect cover crop growth or N uptake. The inclusion of cover crop resulted in more consistent and greater NO3-N loss reductions relative to adjusting fertilizer N application timing from fall to spring. Cover crop reduced the flow-weighted NO3-N concentrations by 39% and 38% and the N load by 40% and 47% when added to spring and fall fertilizer N management systems, respectively. Cover crop proved to be effective in reducing NO3-N loss through sub-surface drainage across the spectrum of N fertilizer management systems common to the Upper Mississippi River Basin.

Long-Term Effects of Poultry Manure Application on Nitrate Leaching in Tile Drain Water

A long-term study (1998 to 2009) was initiated on eleven tile-drained field plots, ranging in size from 0.19 to 0.47 ha, to investigate the effects of poultry manure application on subsurface drainage water quality in Iowa under a corn-soybean rotation system. The experimental treatments included poultry manure at rates of 168 kg N ha-1 (PM) and 336 kg N ha-1 (PM2), each with three replications; nitrogen application from chemical fertilizer, urea ammonium nitrate (UAN), at a rate of 168 kg N ha-1 with four replications; and a control treatment that received 0 kg N ha-1. Subsurface drainage (tile) flow volume was monitored, and drainage samples were collected and analyzed for nitrate-nitrogen (NO3-N). The results from this 12-year study show that NO3-N losses with tile drainage were more likely to occur during the early stages of crop production (April to June) and were more related to the monthly distribution of precipitation than the total rainfall amount. The overall results of this study indicate that applying poultry manure at 168 kg N ha-1 resulted in significantly lower flow-weighted nitrate concentrations (PM < UAN < PM2) and the lowest nitrogen losses to subsurface drain water compared to UAN and PM2 application(PM < UAN < PM2), as well as higher crop yields compared to UAN application. Therefore, it can be concluded that poultry manure application at a rate of 168 kg N ha-1 is an environmentally sound N application practice with good yield potential for corn and soybean production systems with poorly drained soils in the upper Midwest. Future work is recommended to identify new practices and technologies to reduce nitrate loss to water systems.

Comparison of Liquid Swine Manure and Aqua-Ammonia Nitrogen Application Timing on Subsurface Drainage Water Quality in Iowa

In Iowa and many other Midwestern states, excess water is removed artificially through subsurface drainage systems. While these drainage systems are vital for crop production, nitrogen (N), added as manure or commercial fertilizer, or derived from soil organic matter, can be carried as nitrate-nitrogen (NO3-N) to downstream water bodies. A five-year, five-replication, field study was initiated in the fall of 1999 in Pocahontas County, Iowa, on 0.05 ha plots that are predominantly Nicollet, Webster, and Canisteo clay loams with 3% to 5% organic matter located on glacial till within the Des Moines Lobe. The objective was to determine the influence of seasonal N application as ammonia or liquid swine manure on flow-weighted NO3-N concentrations and losses in subsurface drainage water and crop yields in a corn-soybean rotation. Four aqua-ammonia N treatments (168 or 252 kg N ha-1 applied for corn in late fall or as an early season side-dress) and three manure treatments (218 kg N ha-1 for corn in late fall or spring or 168 kg N ha-1 in the fall for both corn and soybean) were imposed on subsurface-drained, continuous flow-monitored plots. Precipitation during the drainage season (March to November) was slightly below the long-term norm (722 mm) for all four years in the study period and ranged from 615 mm in 2001 (85% of normal) to 707 mm (98% of normal) in 2004. Monthly rainfall was highly variable, and subsurface drainage, or the lack thereof, usually mimicked the precipitation patterns. On average, 69% of subsurface drainage occurred in May and June of each year, with lower amounts in April and July. Four-year average flow-weighted NO3-N concentrations measured in drainage water were ranked: spring aqua-ammonia 252 (23 mg L-1) = fall manure 168 every year (23 mg L-1) > fall aqua-ammonia 252 (19 mg L-1) = spring manure 218 (18 mg L-1) = fall manure 218 (17 mg L-1) > spring aqua-ammonia 168 (15 mg L-1) = fall aqua-ammonia 168 (14 mg L-1). Corn yields were significantly greater (p = 0.05) for the spring and fall manure 218 rates than for non-manure treatments. Soybean yields were significantly greater (p = 0.05) for the treatments with a spring nitrogen application to the previous corn crop. Overall, under the slightly dry to normal precipitation conditions of this study, corn yields and NO3-N concentrations in subsurface drainage were not significantly different (p = 0.05) between fall and spring treatments at the 168 aqua-ammonia or 218 kg ha-1 N manure N rates.

Evaluation of the Root Zone Water Quality Model (RZWQM) for Southern Ontario: Part II. Simulating Long-Term Effects of Nitrogen Management Practices on Crop Yield and Subsurface Drainage Water Quality

Abstract Loss of nitrogen from the agricultural production system is of concern in Ontario. The challenge for researchers and farmers is to fulfill crop water requirements while limiting chemical movement with surface and subsurface runoff. The main objective of this study was to evaluate the long-term effects of current N management practices for corn production for two different soil types using the Root Zone Water Quality Model (RZWQM) for southern Ontario conditions. The model simulated the amount of subsurface tile drainage, residual soil nitrate-nitrogen (NO3-N), NO3-N in subsurface drainage water, and crop yield. The validated RZWQM for silt loam and sandy loam soils showed that the relative long-term effectiveness of the most economic rate of nitrogen (MERN) for corn production fluctuates significantly from year-to-year in response to weather patterns. In addition, soil type had a small but significant effect on the MERN. Side-dress application of N on sandy loam resulted in significant reduction in corn yield and NO3-N loss to shallow groundwater. Also, crop rotation from corn-soybean to corn-soybean-soybean resulted in a greater reduction of NO3-N loads in the tile outflow on silt loam soil than on sandy loam soil. Overall, the RZWQM simulated tile drain flow, NO3-N loss, and crop yield with reasonable accuracy. However, more field work is needed to assist with identifying suitable values for a number of coefficients used in the RZWQM's nutrient component for Ontario conditions.

Modelling Approaches for Subsurface Drainage Water Quality Management

Abstract Contamination of surface waters by agricultural activities is a serious problem. Two different modelling approaches to simulate nutrient and pesticide transport in subsurface drained soils were investigated in this study. First, artificial neural network (ANN) models, a trainable fast back-propagation (FBP) network and a self-organizing radial basis function (RBF) network, were developed for simulation of NO3--N concentration in tile effluent. Second, a hydrologic model, DRAINMOD, was linked with a chemical transport model, GLEAMS, to simulate chemical transport of atrazine through the soil into subsurface drain outflow. The ANN models and linked DRAINMOD-GLEAMS model were calibrated and validated against experimental data collected at the Greenbelt Research Farm of Agriculture Canada during the years 1988, 1989 and from 1991 to 1994. Several statistical parameters were calculated to evaluate model performance. A comparison of results indicated that the RBF neural network model was superior to the FBP model in predicting drain outflow and NO3--N concentration. Results obtained from the linked DRAINMOD-GLEAMS model demonstrate that atrazine simulations were underpredicted in subsurface drain outflows for spring and fall seasons. Both modelling approaches provide a useful tool for management of fertilizer/manure and pesticides transport through soil and crop root zones into surface water.

Simulating nitrogen management effects of subsurface drainage water quality

Increased level of NO 3-N in the drinking water supplies is a major health concern these days. The long-term effects of actual nitrogen (N) fertilizer management practices are not well understood. The use of computer models allows the simulation of different N management practices on a long-term basis and their related effects on water quality. The RZWQM (Root Zone Water Quality Model, Version 3.0) was used to simulate the long-term (1978–1992) impacts of N management practices (single N applications at 50, 100, 150, and 200 kg per ha; and single and split N applications at 150 and 200 kg per ha) on NO 3-N losses with subsurface drain flows and crop yields under two tillage systems (moldboard plow (MB) and no till (NT)). Simulations conducted in this study were based on input parameters calibrated by Singh et al. ( J. Environ. Qual., in press) for NO 3-N transport to subsurface drains. However, calibration of some additional parameters was required in this study for long-term simulations. The long-term climatic data and soil properties data for these simulations were obtained from a water quality research site at Nashua, Iowa. The results of this study showed that increasing rates of N applications (50, 100, 150, and 200 kg per ha) resulted in increased NO 3-N losses with subsurface drain flows and increased crop yields. However, increasing rates of NO 3-N losses and crop yields were not linearly proportional with increasing rates of N applications. These trends were similar for both MB and NT treatments. Also, NO 3-N losses and crop yields were not significantly different under single and split N applications at both 150 and 200 kg per ha levels of application. The single N application of 150 kg per ha was considered the best N application practice as the simulated NO 3-N losses under this practice were reduced considerably (40.3% less in MB and 52.4% less in NT) when compared with the single N application of 200 kg per ha. At the same time, the reduction in crop yields at 150 kg per ha single N application was very small (5.9% reduction under MB and about 6.1% under NT) when compared with the crop yields at 200 kg per ha single N application. This study also shows that RZWQM can be used successfully in evaluating similar N management schemes for other geographic regions of the world by utilizing site-specific data on soils, geological features, crops, and climatic parameters such as rainfall and evaporation.

Subsurface Drainage Water Quality from Structured Soil

The often rapid arrival of pesticides at the ground water has been explained by the concept of preferential movement of water and solutes through the soil. To facilitate understanding of these transport processes, a drainage study was conducted by applying a nonadsorbed tracer to plots drained by subsurface drains. Three management practices were employed: no-till, conventional-till, and conventional-till with incorporation of the tracer. The plots were irrigated with 71–203 mm of water. Drainage line outflow and tracer concentration in the outflow were monitored for up to 52 hr. The resulting soil profiles were analyzed for tracer concentration. The main effect of plowing and incorporating the tracer was a more uniform concentration in the resulting profile. A simple mixing-layer model was used to predict the rate at which the tracer was transported out of the root zone into the layers below. The model was found to be in reasonable agreement with drainage outflow patterns, especially from the incorporated plots. These results may be helpful for future development of best-management practices for controlling the effects of agriculture on environmental pollution.

Tillage and Split N-Fertilization Effects on Subsurface Drainage Water Quality and Crop Yields

ABSTRACT FIELD experiments were conducted to study the effects of no-till and conventional tillage, and single and slit N-fertilizer applications, for continuous corn production on the leaching of nitrate-nitrogen (NO3-N) through subsurface drainage water and below the root zone. The comparison between conventional and no-till was made by applying a single application of 175 kg-N/ha at the time of planting, and the comparison between single and split N applications was made for the no-tillage system. Six experimental plots, each drained with a single subsurface drain, were intercepted by installing sumps for measuring drain flow rates and collecting drainage water samples for NO3-N analyses. Also, four sets of piezometers were installed for deep water sampling. In the first year of the experiments, tillage and N-fertilizer management schemes did not significantly affect NO3-N concentrations in drainage. However, in the third year, the average NO3-N concentrations in drainage from conventional tillage plots were significantly greater than those of no-till plots when a single application of 175 kg-N/ha was made. The results of this study indicate that split N-applications totaling 125 kg/ha reduced NO3-N concentrations in drainage compared with a single, higher rate of application of 175 kg/ha for the no-tillage treatment.

Predicting EC for Drainage Water Management

In 1982, 405 measurements of the subsurface drainage water quality parameter electrical conductivity (EC) in dS/m were collected. The data were obtained from 15 subsurface drains on 9.3 ha (23 acres) of irrigated agricultural land at Fallon, Nevada. The temporal and spatial variabilities of EC were studied using time series concepts. Autocorrelation functions (ACF) were used to evaluate the magnitude of temporal and spatial variations of EC. Results suggest that an 11‐week period is the maximum time interval for sampling and that the sampling spatial interval of 36.6 m (120 ft) is too large. Autoregressive integrated moving average (ARIMA) models for both temporal and spatial structures were established through the Box‐Jenkins time‐domain modeling process. The degree of uncertainty of the forecasts were tested using after‐thefact forecast procedures. These models can be used for various purposes such as forecasting future values and determining the transfer function, which provides a way to relate water m...

Subsurface Drainage Water Quality from Land Application of Swine Lagoon Effluent

ABSTRACT WATER quality was monitored for subsurface drainage from small plots receiving 325, 650 and 1300 kg N/ha/yr from sprinkler-irrigated swine-lagoon effluent. Subsurface flow volumes and nutrient concentrations are reported for 20 months at the end of a 6-yr treatment period. Nutrient mass balances for nitrogen and phosphorus which include uptake by Coastal bermudagrass, soil accumulation, surface runoff, subsurface drainage and an estimate of nutrients leaching below the root zone are reported.