Controlled Drainage-subirrigation Research Articles

Water table management impacts on phosphorus loads in tile drainage

Increased phosphorus (P) concentrations, consistently exceeding Quebec's surface water quality standard of 0.03 mg L −1 total P, caused increased P loads in tile drainage from controlled drainage/subirrigation (CD/SI) plots compared to free drainage (FD) plots in a field study carried out in 2005 in Coteau-du-Lac (southwestern Quebec, Canada). This happened even though the total outflow volumes from CD/SI plots were reduced by 27% compared to FD plots. Of the total P concentration, around 96% was in the form of dissolved P under both treatments. The results also showed that CD/SI had no effect on the soil P concentration and P saturation. During the experiment, the SI water added about 0.84 kg P ha −1, which was negligible compared to the fertilizer input on the field, but represented about 8.5 times the average total P loss from CD/SI plots. However, a laboratory soil column experiment, in which the two drainage treatments were simulated and P-free water was used for SI, also showed increased P concentrations under CD/SI. This confirmed that the increased P loads in tile drainage under CD/SI were most likely caused by an increase in P solubility due to the shallow water table inherent to the water table management system rather than by the addition of P from the SI water.

DRAINAGE SYSTEM IMPACTS ON SURFACE RUNOFF, NITRATE LOSS, AND CROP YIELD ON A SOUTHERN ALLUVIAL SOIL

Excess rainfall and subsequent surface runoff is a challenge to farmers of the Lower Mississippi River Valleyregion. In 1993, we established an experimental field site in Baton Rouge, Louisiana, consisting of 16 hydraulically isolatedplots (0.2 ha) on a Commerce soil (Aeric Fluvaquents). Our objective was to determine drainage system impacts on surfacerunoff, subsurface drainage effluent, nitrate loss, and corn (Zea mays L.) yield. We evaluated the following drainage systems(four replications) in 1995 and 1996: surface drainage only (SUR), controlled subsurface drainage at 1.1 m below the soilsurface (DCD), and shallow water table control at a 0.8 m depth via controlled -drainage/subirrigation (CDSI). Planting date,fertility management, and minimum tillage were consistent across treatments. When compared to SUR, DCD and CDSI didnot reduce surface runoff or nitrate loss in runoff. This is in contrast to previous research showing that subsurface drainagesystems decreased runoff on this soil, the difference being that we did not use deep tillage. Our results suggest that subsurfacedrainage systems should be coupled with deep tillage to reduce nutrient loss in runoff from this alluvial soil. DCD and CDSIcontrolled the shallow water table, but the increased annual effluent from subsurface drainage increased nitrate losscompared to SUR. DCD and CDSI had no affect on corn yield under these rainfall conditions. With respect to nitrate lossand crop yield in this region, typical SUR drainage may be the best management practice (BMP) in the absence of effectiverunoff mitigation, such as deep tillage.

Effect of tillage and water table control on evapotranspiration, surface runoff, tile drainage and soil water content under maize on a clay loam soil

Two tillage and two water table control treatments under continuous maize cropping were evaluated over a 3-year period (1992–1994) for their effects on evapotranspiration, surface runoff (SR), tile drainage (TD) and soil water content in the root-zone on a clay loam soil in southern Ontario. The tillage treatments included soil saver (SS, reduced tillage) and moldboard plow (MP, conventional tillage). The water table control treatments included controlled drainage-subirrigation (CDS) and regular tile drainage (DR). There was no significant difference ( P<0.05) in evapotranspiration estimates between the SS and MP tillage treatments. The SS tillage increased SR compared with MP tillage during the non-cropping periods in 1993 and 1994, but not in 1992. Relative to MP, the SS tillage increased soil profile water content during the cropping period but decreased soil profile water content during the non-cropping period in 1992. The CDS treatment produced significantly higher ( P<0.05) evapotranspiration and soil water content than the drainage treatment during the dry 1993 and 1994 years, but not during the wet 1992 year. The CDS treatment also had significantly lower ( P<0.05) TD and higher SR than the drainage treatment. For all the treatments, over 65% of SR and TD occurred in the 5 month non-cropping period from November to March. Of the total annual water input (precipitation and/or subirrigation) to the field site, 8% was partitioned to SR, 30% was partitioned to TD, 55% was removed by crop and soil evapotranspiration and 7% was accounted for by changes in soil profile water content.

Tillage, intercrop, and controlled drainage-subirrigation influence atrazine, metribuzin, and metolachlor loss.

Atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] have been found with increasing occurrence in rivers and streams. Their continued use will require changes in agricultural practices. We compared water quality from four crop-tillage treatments: (i) conventional moldboard plow (MB), (ii) MB with ryegrass (Lolium multiflorum Lam.) intercrop (IC), (iii) soil saver (SS), and (iv) SS + IC; and two drainage control treatments, drained (D) and controlled drainage-subirrigation (CDS). Atrazine (1.1 kg a.i. ha-1), metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazine-5(4H)-one] (0.5 kg a.i. ha-1), and metolachlor (1.68 kg a.i. ha-1) were applied preemergence in a band over seeded corn (Zea mays L.) rows. Herbicide concentration and losses were monitored from 1992 to spring 1995. Annual herbicide losses ranged from < 0.3 to 2.7% of application. Crop-tillage treatment influenced herbicide loss in 1992 but not in 1993 or 1994, whereas CDS affected partitioning of losses in most years. In 1992, SS + IC reduced herbicide loss in tile drains and surface runoff by 46 to 49% compared with MB. The intercrop reduced surface runoff, which reduced herbicide transport. Controlled drainage-subirrigation increased herbicide loss in surface runoff but decreased loss through tile drainage so that total herbicide loss did not differ between drainage treatments. Desethyl atrazine [6-chloro-N-(1-methylethyl)-1,3,5-triazine-2,4-diamine] comprised 7 to 39% of the total triazine loss.

Tillage and Controlled Drainage‐Subirrigated Management Effects on Soil Persistence of Atrazine, Metolachlor, and Metribuzin in Corn

AbstractThe occurrence of herbicides in surface waters necessitates the development of management practices to reduce herbicide loss through tile drainage and surface runoff. Four tillage‐intercrop systems: moldboard plow (MB), moldboard plow with rye grass (Lolium multiflorum Lam.) intercrop (MB+IC), soil saver (SS), and soil saver with rye grass intercrop (SS+IC), and two water table management treatments: controlled drainage‐subirrigation (CDS) and no control drainage (D) were investigated for their effect on herbicide persistence. Atrazine [2‐chloro‐4‐ethylamino‐6‐isopropylamino‐s‐triazine] (1.1 kg ha−1), metribuzin [4‐amino‐6‐(1,1‐dimethylethyl)‐3‐(methylthio)‐1,2,4‐triazin‐5(4H)‐one] (0.5 kg ha−1), and metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methylethyl) acetamide] (1.68 kg ha−1) were strip applied in a corn (Zea mays L.) management system to reduce herbicide inputs 50%. Tillage‐intercrop system had little consistent effect on soil residues of the herbicides at 0‐ to 10‐cm depth. Control drainage‐subirrigation decreased haif‐life of atrazine and metolachlor in one of two years. Half‐life for atrazine ranged from 34 to 56 d, metribuzin 24 to 35 d, and metolachlor 40 to 79 d, with longer half‐life in dry years. Des‐ethyl atrazine [2‐chloro‐4‐amino‐6‐isopropylamino‐s‐triazine], the major metabolite of atrazine, persisted along with atrazine and metolachlor to the next planting season. Less than 10% of the original herbicide application was recovered the year following application. It was concluded that environmental factors such as rain affect herbicide residues more than cultural practices.

Improved Water Quality through Water Table Management in Eastern Canada

A two-year field study was conducted in eastern Ontario to evaluate the effects of water table management on the quality of subsurface drain flows. Drainage discharge volumes and NO3--N concentrations in drainage effluent were monitored during the growing seasons. The 3.5 ha experimental field was strip-cropped with corn (Zea mays L.) and soybean (Glycine max Merr.). Controlled-drainage subirrigation was used to manage water from precipitation and subirrigation. The two controlled water table treatments were 50 cm and 75 cm from the surface. There was also a conventional free-drainage treatment (FD). In 1995, mean NO3--N concentrations in drainage water were reduced by 84% and 75% by the 50 and 75 cm controlled water table depths, respectively. In 1996, drain flow volumes and NO3--N concentrations were significantly reduced relative to free drainage. Total drain flow was reduced by 42% by the 50 cm controlled water table, while NO3--N concentrations were reduced by 61% and 52% by the 50 cm and 75 cm contr...

Effect of Agricultural Drainage on Water Quality in Mid-Atlantic States

Agricultural drainage development in the form of drainage alone and controlled drainage subirrigation (CD-SI) has created environmental concerns. The primary concern is increased loading of nutrien...

Drainage and Irrigation Effects on Cotton Production

Excessively wet and dry soil conditions can occur during the same year in the southeastern Coastal Plain of the United States. Water management systems that provide both subsurface drainage during wet soil conditions and irrigation during dry soil conditions are desired. Several water table management alternatives, possibly with surface irrigation such as microirrigation, could satisfy these needs. Three water table management (WTM) systems and microirrigation were evaluated for three cotton cultivars on a southeastern Coastal Plain soil during 1987-1989. The WTM systems included controlled drainage-subirrigation (CDSI), controlled drainage (CD), and subsurface drainage (SSD). All WTM systems had both surface microirrigation and rainfed treatments. Cotton cultivars were Coker 315, DPL 50, and DPL 90. Seasonal rainfall, subirrigation, and microirrigation amounts varied considerably during the three-year period. Water requirements for subirrigation in the CDSI system were high (1477 to 2841 mm), but neither microirrigation nor subirrigation water requirements were closely related to seasonal rainfall amounts. Cotton lint yields among WTM systems were significantly different in two of three years; yields for the CDSI system were lowest (836 and 766 kg/ha) and yields for CD and SSD were highest (1022 and 942 kg/ha, respectively). Wetter-than-optimum soil conditions in all irrigated treatments, especially in combination with the CDSI system, probably caused the reduced yield. Microirrigation produced significantly greater lint yields than the rainfed treatments in the first two years of the study (1127 and 1116 kg/ha versus 492 and 801 kg/ha), but not in the last year (872 versus 874 kg/ha) when seasonal rainfall was least of the three years but was better distributed. There were significant yield differences among cotton cultivars in two years, but no cultivar consistently produced the greatest or least yield. Cotton yield increases obtained with these WTM system-microirrigation combinations suggest the need to control the water table closer to the soil surface in southeastern Coastal Plain soils when surface irrigation is not used. The CDSI could provide a profitable management alternative if a water table fluctuates near the soil surface much of the time, especially during the growing season. Where subsurface drainage is needed part of the year, it may be more profitable to use CD or SSD systems with surface irrigation, especially when maintaining the water table near the soil surface in CDSI systems requires a large water volume. However, the combined cost of the subsurface drainage and microirrigation systems would be very high and might not be profitable for crops such as cotton.

Controlled-drainage/Subirrigation System Automation Based on Soil Water Potential

An automated computer-based system was developed to control field scale controlled-drainage/subirrigation (CD-SI). The control system was designed to maintain the optimum soil water conditions in the root zone by monitoring the soil water potential and adding or removing water or remaining idle as needed.

Water Table Management Practice Effects on Water Quality

Impacts of water table management (WTM) practices on water quality were modeled using a linked version of CREAMS and DRAINMOD (Parsons and Skaggs, 1988). The CREAMS denitrification component and the linked DRAINMOD-CREAMS model were modified to simulate daily hydrology (runoff, infiltration, evaporation, and soil moisture content), erosion, and nutrient processes for different WTM conditions. Measured data from Baton Rouge, Louisiana, were used to validate the linked model, and then controlled drainage-subirrigation (CD-SI) was simulated to investigate the effects of different WTM systems on runoff, erosion, and nitrogen losses.

Drainage‐Subirrigation Effect on Water Quality in Georgia Flatwoods

The effects of controlled‐drainage‐subirrigation (CD‐SI) systems on subsurface and outflow water quality must be evaluated before these systems can be promoted for use in the Georgia flatwoods region of the eastern Coastal Plain. In this paper, Nitrate‐nitrogen (N), ammonium‐N, and orthophosphorous (P) concentrations are measured from shallow subsurface wells and outlets of a CD‐SI system in the Georgia flatwoods for comparison to adjacent forested and grassland areas (the most common current land uses). Nitrate‐N concentrations did not exceed 10 mg/L from any of the outflow samples although almost 6% of the well samples taken from the CD‐SI area had concentrations exceeding 10 mg/L, Nitrate‐N concentrations in most of the wells in the CD‐SI area were significantly higher than in the forested and cleared areas. Ammonium‐N and ortho‐P concentrations were relatively low and do not appear to be a problem based on this limited data. No significant differences in ammonium‐N and ortho‐P concentrations were shown between any of the sites. Ammonium‐N concentrations did exceed 2 mg/L from at least one sample of the scrub forest, one of the CD‐SI blueberry sites, an open ditch (1.8 m depth), and one of the cleared unirrigated sites. Ortho‐P concentrations ranged from 0 to 1.94 mg/L, with average concentrations from all sites near 0.1 mg/L.

Drainage-Subirrigation Design For Pelham Loamy Sand

ABSTRACT This project was conducted on the Bell farm located in Pierce County, GA on Pelham loamy sand soil. The study area included 40 ha of land under controlled drainage-subirrigation (CD-SI) system of which 38 ha were in blueberries. The system installation included two drain spacings of 15.3 and 20 m, and two types of control structures for the drainage system outlet water level, which were an open ditch and a closed conduit system network. The blueberry section of the field was in a closed conduit system network with lateral drains spaced at 15.3 m. Seventeen punch-tape recorders were used to measure the water table elevations in the soil profile within the field over the drain tiles, and midway between drainlines, at the open ditch and closed system control structures (one for each), and in an undrained-nonirrigated section of the farm. A punch-tape rainfall recorder was also used to measure rainfall at the site. Surface runoff, drainage effluent, or subirrigation volume was not measured. Experimental results showed that the water table and soil-water conditions could be adequately managed in the blueberry field, thus excellent crop growth and yield resulted. DRAJNMOD, a water management model for shallow water table conditions, was used to simulate the system performance for the study site. Simulation results indicated that a subsurface drain spacing of 20 m is satisfactory for controlled drainage-subirrigation (CD-SI) systems for Pelham loamy sand soils in Pierce County, GA. Simulations were done using 20 years of climatological data from Augusta, GA. Additional research is needed to develop specific design guides for other soil types in the Georgia Flatwoods region.

Design, Operation, and Maintenance of Controlled-Drainage/Subirrigation (CD-SI) Systems in Humid Areas

THE design, operation, and maintenance of controlled-drainage/subirrigation (CD-SI) systems are covered from the viewpoint of assisting the farmer, practicing engineer, contractor, and SCS personnel. A nomogram is presented for soils, permeability, approximate drain spacings, and ratio of CD-SI system spacing to drainage system spacings. Steps used in the design of a CD-SI system on a farm with sloping fields are covered in this report.