doi:10.2489/jswc.67.6.167A RESEARCH INTRODUCTION Drainage water management R. Wayne Skaggs, Norman R. Fausey, and Robert O. Evans

his article introduces a series of the most productive in the world. Drainage needed. Drainage water management, or papers that report results of field ditches or subsurface drains (tile or plastic controlled drainage, emerged as an effec- T studies to determine the effec- drain tubing) are used to remove excess tive practice for reducing losses of N in tiveness of drainage water management water and lower water tables, improve traf- drainage waters in the 1970s and 1980s. (DWM) on conserving drainage water ficability so that field operations can be The practice is inherently based on the and reducing losses of nitrogen (N) to sur- done in a timely manner, prevent water fact that the same drainage intensity is face waters. The series is focused on the logging, and increase yields. Drainage is not required all the time. It is possible to performance of the DWM (also called also needed to manage soil salinity in irri- dramatically reduce drainage rates during controlled drainage [CD]) practice in the gated arid and semiarid croplands. some parts of the year, such as the winter US Midwest, where N leached from mil- Drainage has been used to enhance crop months, without negatively affecting crop lions of acres of cropland contributes to production since the time of the Roman production. Drainage water management surface water quality problems on both Empire, and probably earlier (Luthin may also be used after the crop is planted local and national scales. Results of these 1957). Until recent years, the focus of to reduce drainage intensity and conserve Copyright © 2012 Soil and Water Conservation Society. All rights reserved. new studies are consistent with those from drainage research and development was water for crop use during the growing Journal of Soil and Water Conservation previous research reported in the literature to improve its efficiency and increase crop season. Drainage water management is that DWM can be used to reduce N losses yields and profits. Research beginning in typically applied by installing a structure

(primarily in the nitrate nitrogen [NO3- the 1970s (e.g., Baker et al. 1975; Gambrell in the drainage ditch or subsurface drain N] form) from subsurface drained fields. et al. 1975) showed that agricultural drain- that allows the outlet water level elevation The measured impact varied over a wide age has significant impacts on surface to be adjusted or managed (figure 1). range (18% to more than 75% reduction water quality. Subsurface drainage reduces Drainage water management, or con- in N loss to surface waters), depending on surface runoff, sediment losses, and the trolled drainage, has been used for many drainage system design, location, soil, and movement of contaminants attached to years to reduce subsidence of drained site conditions. Crop yields were increased the sediment into surface waters. However, organic soils in the Florida Everglades and by DWM on some sites and not on others, it increases the losses of N (Gilliam et al. other locations (Clayton and Jones 1941; with the year-to-year impacts of DWM on 1999; Dinnes et al. 2002) and is cited as Stevens 1955). The first experiments show- 67(6):167A-172A yields dependent on weather conditions, as one of the major sources causing algal ing that this practice could be effective for well as the above factors. Papers reporting blooms and hypoxia in major water bod- reducing N losses in drainage water were advances in the development of datasets ies. Nitrogen losses from intensively conducted on drained irrigated lands in and models to predict the impact of drain- drained cropland in the US Midwest are California (Meek et al. 1970; Willardson et age intensity and DWM on hydrology and considered a major contributor to exces- al. 1972), but the practice was not applied. www.swcs.org water quality at watershed and basin scales sive N and hypoxic conditions in the Gulf Gilliam et al. (1979) determined that CD are also included in this collection (Mori- of Mexico (Mitsch et al. 2001; Rablais et could be used during the winter months asi et al. 2012; Heilman et al. 2012). al. 2002; David et al. 2010). By the end in North Carolina to reduce N losses from Drainage is necessary for agricultural of the last century, the development of drained agricultural (corn–wheat–soy- production on about 25% of cropland methods to reduce off-site environmental bean rotation) lands by 40% to 50%. This in the United States and Canada (Pavelis impacts had become an important objec- was followed by a number of additional 1987; Shady 1989). Globally, about 33% tive of drainage researchers and engineers. research studies and field trials (Skaggs of the world’s cropland requires drainage The development of methods to and Gilliam 1981; Doty et al. 1987; Evans (Smedema et al. 2004). Without drainage, reduce losses of N in drainage waters has and Skaggs 1989; Evans et al. 1989, 1995) farming would not be possible on many of become a primary objective in addressing in the coastal plain, where excessive N in these lands; with drainage, they are among the environmental impacts of agricultural drainage waters had been cited as a signifi- drainage. Reducing N losses is difficult cant contributor to algal blooms and fish R. Wayne Skaggs is William Neal Reynolds because the nitrate form is mobile in kills in the coastal streams and estuaries. Distinguished University Professor and Robert soil solution and may be readily leached The practice was accepted as a best man- O. Evans is professor and Department Head at with subsurface drainage water. A num- agement practice by the state of North the Department of Biological and Agricultural ber of methods may be used to reduce Carolina with cost sharing for the control Engineering, North Carolina State University, Raleigh, North Carolina. Norman R. Fausey losses (Dinnes et al. 2002; Heilman et al. structures. It was heavily promoted by the is research leader and supervisory research 2012). They include source reduction by USDA Natural Resources Conservation soil scientist at the Soil Drainage Research fertilizing at appropriate rates, cover crops, Service (NRCS), the Cooperative Unit, USDA Agricultural Research Service, Columbus, Ohio. routing drainage water through wet- Extension service, and other federal and lands, use of biofilters, and DWM. All are state agricultural and environmental agen-

JOURNAL OF SOIL AND WATER CONSERVATION NOV/DEC 2012—VOL. 67, NO. 6 167A Figure 1 Management Coalition (ADMC) was Drainage management structures for subsurface drains and open ditch outlets. organized in 2005. ADMC works at the local and state level to educate farm, drain- age, and conservation groups as well as local, state, and federal authorities to build understanding of the latest drainage water management systems and technologies. ADMC was awarded and managed the five-state USDA NRCS funded national DWM Conservation Innovative Grant project involving land-grant university, state agency, and ARS personnel. Five of the seven papers in this issue report results obtained in this project. Drainage water management (Practice 554) was identified as a priority practice in the USDA NRCS Mississippi River Copyright © 2012 Soil and Water Conservation Society. All rights reserved. Basin Initiative initiated in 2009. Adoption Journal of Soil and Water Conservation of the practice was negligible during the first 2 years leading NRCS to establish a National Agricultural Water Management Team to assist states in the voluntary con- cies as a recommended practice for water Service/National Institute of Food and servation efforts to reduce nitrates leaving conservation and improved water quality Agriculture) to establish an interagency drained farmland, with an initial focus to (Evans and Skaggs 2004). More than 4,000 task force identified as the Agricultural address the intensively drained farmlands structures have been installed since the Drainage Management Systems Task in the Upper Mississippi River Basin. A program began in 1984. This application Force. The Task Force was formally estab- Phase I Team was formed in September of CD (now referred to as DWM) was lished in early 2003 as a technical work 2010 to provide recommendations for the subject of a special issue of the Journal group to assist in addressing and resolving strategic actions the NRCS should take 67(6):167A-172A of Soil and Water Conservation in 1992 water quality issues on drained agricultural to increase successful producer adoption (Stone et al. 1992; Evans et al. 1992). lands. The Task Force developed a Charter of DWM within the Mississippi River Research conducted in glacial-derived and an Action Plan through meetings and Basin Initiative. The team was charged soils in colder climates—Ontario (Lalonde discussions that included state and federal with assessing the current use of the prac- et al. 1996; Tan et al. 1998; Gaynor et agencies, nongovernment organizations, tice, identifying barriers to the adoption www.swcs.org al. 2002; and Drury et al. 2009), Ohio and industry representatives. The Action of DWM, determining and considering (Fausey 2005), and Sweden (Wesstrom and Plan ultimately led to recommendations lessons learned through past experience, Messing 2007)—showed that DWM was to USDA to encourage additional research and developing strategic action recom- effective in reducing losses of N in drain- throughout the Midwest to document the mendation that will increase adoption of age waters in those areas. Collectively, the environmental benefits of DWM, revise DWM. Based on the Phase I Team report, above results supported the potential use the Practice 544 standard nationally and a Phase II Team was charged to increase of DWM in the US Midwest. for individual states, seek Conservation the adoption of agricultural DWM for Innovation Grant proposals to demonstrate conservation benefits. An Action Plan AGRICULTURAL DRAINAGE and evaluate Practice 544 Drainage Water has been developed to guide the Team in MANAGEMENT SYSTEMS TASK FORCE Management, offer cost-share incentives achieving its goals. The Team organized Concern about the extent of hypoxia in to encourage adoption of the practice, and and held a National Summit in Minnesota the Gulf of Mexico and evidence to sup- develop a strategy to promote adoption of in October 2011 to increase the nation- port the contribution of soluble nutrients the practice. wide adoption of DWM as part of a

(especially NO3-N) from the Mississippi Formation of the Task Force by USDA conservation system through understand- River Basin to nourish the algal bloom created a realization among the drainage- ing of past history, current situation, and heightened in the early 2000s. Discussions affiliated industries that they had expertise future opportunities. within USDA about possible sources and and incentive to contribute in assisting solutions led the Partnership Management the agricultural and environmental com- POTENTIAL FOR DRAINAGE WATER Team (USDA Agricultural Research munities in improving water quality and MANAGEMENT IN THE US MIDWEST Service [ARS]; USDA NRCS; Cooperative increasing yields for food and energy pro- Jaynes et al. (2010) evaluated the poten- State Research, Education, and Extension ducers. Thus, the Agricultural Drainage tial water quality impact of DWM in the

168A NOV/DEC 2012—VOL. 67, NO. 6 JOURNAL OF SOIL AND WATER CONSERVATION US Midwest. They used USDA NRCS, and funded by USDA NRCS through the results of published studies on effect of United States Geological Survey, and US Conservation Innovation Grant program. DWM on N losses in drainage water is Environmental Protection Agency data- The project resulted in the demonstration given in table 1. Examination of results of bases to determine that approximately 10 of DWM on a total of 20 sites in the states individual studies indicates that N losses in million ha (25 million ac) of cropland in of Indiana, Illinois, Iowa, Minnesota, and drainage water are almost entirely in the the region are suitable for DWM (soils Ohio. Collectively, these sites provided nitrate form. Thus, the effects of DWM normally drained with slopes <0.5%). opportunities for hundreds of farmers, land shown in table 1 on N losses may be inter-

The Root Zone Water Quality Model, owners, conservation and environmental preted as the effect on NO3-N losses. The coupled with Decision Support System professionals, and the general public to see table was originally presented by Skaggs et for Agrotechnology Transfer crop growth DWM first hand and learn about its oper- al. (2010). Results from papers published models, were used to simulate the impact ation and benefits. The DWM sites were since that time, including those presented of DWM on reducing nitrate losses from located adjacent or close to convention- in this issue, have been added. Because our drained fields across the Midwest. Results ally drained sites with the same soil series, focus is on the effect of DWM, or CD, on indicated that application of DWM on 4.8 crops, and farming practices. Drainage water conservation and N losses, the table million ha (12 million ac) used to grow outlets were instrumented to measure does not include studies on subirrigation. corn in the region would reduce NO3-N flow rates and determine N losses in the Nor does it include the results of model- losses from drained fields to surface waters drainage water, and the paired watershed ing studies. Such studies have been very Copyright © 2012 Soil and Water Conservation Society. All rights reserved. by 83 million kg y-1 (180 million lb yr-1). approach was used to determine the effect useful in understanding how DWM func- Journal of Soil and Water Conservation When the expenses for control struc- of DWM on subsurface drainage volumes, tions under different weather conditions, tures, installation, and management were N loads, and crop yields. system designs, and operational strategies considered, the cost per kilogram of Collecting research quality data on and in projecting the potential impact of removing NO3-N from surface waters, or demonstration projects is notoriously DWM on N loads if applied at state or of preventing its entry, was among the least difficult as the time required to get sites regional scales (Jaynes et al. 2010). In addi- expensive of alternative methods. Benefits selected, instrumented, and treatments tion, models would logically play a critical due to drainage water conservation and established often limits the time avail- role in evaluating the effect of DWM on increased yields would further lower the able to collect a dataset of appropriate annual N loads for purposes of nutrient effective cost of reducing N loads to sur- length and quality to test the hypothesis. trading or related incentives to promote N face waters. In some cases (Jaynes 2012; Helmers et loss reduction to surface waters (Skaggs et Control structures (figure 1) can be al. 2012), the demonstration sites were al. 2012). However, table 1 includes only 67(6):167A-172A fitted to the outlets of existing drainage established consistent with a field research those studies in which effects of DWM on systems. DWM will be most effective on approach, where the effect of DWM could annual drainage volumes and N losses have relatively flat lands where one structure be compared to conventional drainage in been determined from field measurements will affect the outlet water level and drain- well-instrumented, field-scale, replicated and observations. age rates from relatively large areas (Strock plots. In others (Cooke and Verma 2012; Studies presented in this issue increased www.swcs.org et al. 2011). For new systems, the network Ghane et al. 2012; Adeuya et al. 2012), our database on the impact of DWM on of lateral and main drains can be designed paired DWM and conventionally drained N loss from 12 to 20 sites. DWM reduced to accommodate DWM by following sites were established on farmer-oper- measured average annual drainage vol- contours and breaking the field into man- ated, production-scale fields, located on a umes from 18% to over 85%, depending agement zones such that a single structure range of soils and conditions across a wide on site and year. Consistent with obser- can be used to manage drainage water region of a state. There are advantages and vations in previous studies, DWM did levels and rates from relatively large areas. disadvantages to both approaches. Overall, not greatly affect NO3-N concentrations. This would allow DWM to be applied to results of this project provide valuable So, its effect on N loads, on a percentage a larger percentage of subsurface drained information and greatly expand our basis, was similar to its effect on drain- lands and would greatly increase its effi- database on the effectiveness of DWM, age volumes, with reductions of NO3-N ciency (Pitts 2008). especially in the large area of subsurface loads among the sites from 18% to 79%. drained cropland in the US Midwest. The ranges in response to DWM, for both FIVE-STATE DRAINAGE WATER drainage volume and N loads, are simi- MANAGEMENT PROJECT EFFECT OF DRAINAGE WATER lar to those obtained in previous studies, Five of the seven papers in this special MANAGEMENT ON NITROGEN LOSSES some of which were conducted on very section report results from the five-state IN DRAINAGE WATER different soils, cropping systems, and cli- drainage water management project ref- Results contributed by papers presented matological conditions (table 1). erenced above. The project was organized in the special section of this journal issue In addition to showing that DWM sub- by the ADMC in close cooperation with add significantly to our knowledge on stantially reduced drainage outflows and USDA ARS researchers, Land Grant uni- the effectiveness of DWM in reducing N loads in the drainage water in all stud- versity faculty, and state agency personnel N losses to surface waters. A summary of ies conducted, a review of results in table

JOURNAL OF SOIL AND WATER CONSERVATION NOV/DEC 2012—VOL. 67, NO. 6 169A Table 1 Summary of results of field studies of effectiveness of drainage water management in reducing drainage volumes and nitrogen loads (modified from Skaggs et al. 2010).

Reference Location Soil Years Area Drain Drain Control Percent Reduction observed (ha) spacing (m) depth (m) depth* (m) drainage nitrogen loss

Gilliam et al. 1979 North Carolina Portsmouth sandy loam 3 5 to 16 30 and 80 1.2 0.3 to 0.5 50 50 North Carolina Goldsboro sandy loam 3 3 30 1 0.3 85 85 Evans et al. 1989 North Carolina Ballanhack sandy loam 2 4 18 1 0.6 56 56 North Carolina Wasda muck 2 4 100 1.2 0.6 51 56 North Carolina Wasda muck 2 4 18 1 0.6 17 18 Lalonde et al. 1996 Ontario Bainesville silty loam 2 0.63 18.3 1 0.75 49 69 0.5 80 82 Breve et al. 1997† North Carolina Portsmouth 1.2 1.8 22 1.2 0.4 to 0.5 16 20 Tan et al. 1998 Ontario Brookston clay loam 2 2.2 9.3 0.65 0.3 20 19 Gaynor et al. 2002‡ Ontario Brookston clay loam 2 0.1 7.5 0.6 0.3 16 Drury et al. 2009§ Ontario Brookston clay loam 4 0.1 7.5 0.6 0.3 29 31 to 44|| Copyright © 2012 Soil and Water Conservation Society. All rights reserved.

Wesstrom and Messing 2007 Sweden Loamy sand 4 0.2 10 1 0.2 to 0.4 80 80 Journal of Soil and Water Conservation Fausey 2005 Ohio Hoytville silty clay 5 0.07 6 0.8 0.3 41 46 Jaynes 2012 Iowa Kossuth/Ottosen 4 0.46 36 1.2 0.6 18 21 Helmers et al. 2012 Iowa Taintor/Kalona 4 1.2 to 2.4 18 1.2 0.3 37 36 Adeuya et al. 2012 Indiana Rensselaer 2 3 21 1 0.15 to 0.6 19 23 Indiana Rensselaer 2 6 to 9 43 18 Cooke and Verma 2012 Illinois Drummer 2 15 30 1.15 0.15 44 51 Drummer/Dana 1 to 2# 8.1 15 1.15 0.15 44 52 Orion Haymond 1 to 2# 5.7 18 to 21 1.15 0.15 89 79 Patton/Montgomery 1 to 2# 16.2 12 0.85 0.15 38 73

* Control typically removed during seedbed preparation, planting, and harvesting periods. 67(6):167A-172A † Controlled drainage (CD) during the growing season only. CD reduced subsurface drainage volume by 16%; Nitrogen loss from subsurface drain + runoff by 20%. ‡ CD reduced subsurface drainage by 35%, increased surface runoff by 28%, and reduced total outflow by 16%. Nitrogen results were not reported and effects on pesticide loss were reported. § CD reduced subsurface drainage by 29%, increased surface runoff by 38%, and reduced total outflow by 11%. www.swcs.org || CD reduced nitrogen loss by 44% for recommended nitrogen application rates and by 31% for elevated nitrogen rates. # Drainage volume measured for two years and nitrogen losses measured for one year for these locations.

1 raises questions as to what happens to the N may be taken up by the crop in system design, and management strategy. the water that was not removed by drain- response to increased evapotranspiration. For a given year, the effect of DWM on age and why the response to DWM was In cases where the bottom of the profile yields is very dependent on weather con- so different between the different sites remains saturated and anaerobic (reduced) ditions during the growing season. DWM and soils represented. This question was or where seepage water passes through can potentially increase yield by retain- discussed in detail by Skaggs et al. (2010). reduced zones, N may be converted ing drainage water in the profile so that They concluded that DWM reduces sub- through denitrification and lost from the it is available to supply crop needs during surface drainage volumes by increasing profile as nitrogen gas. For moderately subsequent dry periods. During unusually evapotranspiration, increasing seepage, well drained soils, DWM may be equally dry growing seasons, there may be little and increasing surface runoff. The impact or more effective in reducing drain flows, or no drainage water to conserve, so the of DWM on each of these hydrologic but have limited effectiveness in reduc- effect of DWM in such years might be components depends on weather, soil ing N losses as seepage water containing nil. Conversely, in seasons when rainfall

properties, site conditions, drainage system NO3-N may eventually make its way to occurs at about the right time to satisfy design and management, and crops. surface waters through different paths. crop evapotranspiration requirements, What happens to the N? The effec- drainage water conserved by DWM is tiveness of DWM in reducing N losses EFFECT OF DRAINAGE WATER not needed to satisfy evapotranspiration to surface and ground waters depends MANAGEMENT ON CROP YIELDS demands and would likely have little effect on both its effect on hydrology and on The effect of DWM on yields depends on on crop yield. DWM will have maximum N dynamics in the soil profile. Some of soil properties, site conditions, drainage effect on crop yields in years when a wet

170A NOV/DEC 2012—VOL. 67, NO. 6 JOURNAL OF SOIL AND WATER CONSERVATION period during the growing season is fol- Table 2 lowed by a moderately long dry period, Summary of measured effects of drainage water management (DWM) on crop yields. followed by another wet period, etc. Such Reference Location Years Number Crop Effects of DWM conditions provide the best opportunity observed of sites on crop yield for DWM to conserve soil water that can subsequently be used by the crop. Such Tan et al. 1998 Ontario 2 1 Soybean No effect sequences of weather events would logi- Drury et al. 2009 Ontario 2 1 Corn No effect cally happen in some locations more than 2 1 Soybean No effect in others and in some years more than in Wesstrom and Messing 2007 Sweden 4 1 Cereals 2% to 18% increase others. Thus, long-term studies (records) Fausey 2005 Ohio 5 1 Corn No effect are needed to determine average effects of Ohio 5 1 Soybean No effect DWM on crop yields. If other factors are Poole et al. 2011 North Carolina 6 2 Corn 11% increase equal, DWM would be expected to have North Carolina 5 2 Wheat No effect the greatest effect on conserving water and North Carolina 6 2 Soybean 10% increase increasing yields where subsurface drains Delbecq et al. 2012 Indiana 5 2 Corn 5.8% to 9.8% increase are deep and drainage intensity is high. In Jaynes 2012 Iowa 2 1 Corn No effect systems where drains are relatively shallow Iowa 2 1 Soybean 8% increase Copyright © 2012 Soil and Water Conservation Society. All rights reserved. and far apart, or the hydraulic transmissiv- Helmers et al. 2012 Iowa 4 1 Corn Reduced yield Journal of Soil and Water Conservation ity of the soil profile is low, DWM must Iowa 4 1 Soybean No effect be carefully managed to avoid negative Cooke and Verma 2012 Illinois 2 4 Corn No effect impacts on crop yields. 2 3 Soybean No effect Effects of DWM on crop yields as Ghane et al. 2012 Ohio 1 to 2 7 Corn 1% to 19% increase measured in field experiments and dem- in 6 of 9 observations onstration sites are summarized in table 1 to 2 7 Soybean 1% to 7% increase 2. Note that results presented in this issue in 7 of 11 observations constitute a significant percentage of results published on this subject. While there were substantial positive effects of REFERENCES Delbecq, B.A., J.P. Brown, R.J.G.M. Florax, E.J. 67(6):167A-172A DWM on measured yields in some cases, Adeuya, R., N. Utt, J. Frankenberger, L. Bowling, Kladivko, A.P. Nestor, and J.M. Lowenberg- there were negligible or not statistically E. Kladivko, S. Brouder, and B. Carter. 2012. DeBoer. 2012. The impact of drainage water significant effects in others. The relatively Impacts of drainage water management on sub- management technology on corn yields. short period of observation in many of the surface drain flow, nitrate concentration, and Agronomy Journal 104(4):1100-1109. studies may have contributed to the fail- nitrate loads in Indiana. Journal of Soil and Water Dinnes, D.L., D.L. Karlen, D.B. Jaynes, T.C. Kaspar, ure to detect effects of DWM on yields in Conservation 67(6):474-484. J.L. Hatfield, T.S. Colvin, and C.A. Cambardella. www.swcs.org some cases. In only one case was DWM Baker, J.L., K.L. Campbell, H.P. Johnson, and J.J. 2002. Nitrogen management strategies to reduce reported to have a negative effect on yield, Hanway. 1975. 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172A NOV/DEC 2012—VOL. 67, NO. 6 JOURNAL OF SOIL AND WATER CONSERVATION