Agricultural Drainage

Bulletin 871-98

Ohio

Highlights

• Subirrigation research by the USDA-ARS at Wooster and Hoytville indicates that for certain soils, this practice can be very efficient if the system is properly designed for the site and soil conditions. Most importantly, crops respond well to subirrigation when other production management factors are not limiting. Research has considered factors such as water table depth, row spacing, and cultivars. At Wooster, soybean and corn yields were on average 43% and 30% greater, respectively, for subirrigation/drainage systems compared to subsurface drainage alone. Subirrigated corn and soybean yields averaged 203 and 65 bu/acre, respectively, over 6 years of research. Results of five years of subirrigation research at Hoytville (1992-1996) indicate a 21% increase in soybean yields, and a 12% increase in corn yields over that produced from subsurface drained cropland.
  

  Drop logs in a water control structure are adjusted in order to control
  the water table level in a subirrigation/drainage system.

• A daily water quality modeling methodology using remotely sensed data, a field scale process model, and a GIS to assess flow, sediment and agrichemical discharges on small agricultural watersheds has been developed and evaluated. The model incorporates ADAPT (Agricultural Drainage and Pesticide Transport) and has been used on the Rock Creek and Darby Creek watersheds. The method gives good estimates of streamflows, but overpredicts pesticide losses. The potential to predict sediment and nitrate losses was illustrated, but a dynamic delivery ratio and improved denitrification algorithms need to be incorporated into the model. New studies are linking this agricultural model to the SWMM model which better accounts for urban land uses, and to the REMM model which was developed for riparian land uses.
  

  Comparison of predicted average nitrate-N loadings at the watershed
  outlet for different tillage and drainage practices using a watershed
  approach that incorporates ADAPT.

• A working group of over 50 state and federal agency and agricultural organization personnel are developing a new, comprehensive Agricultural Water Management Guide, which includes consideration of: soils, drainage, subirrigation, irrigation, operation and management of drainage systems, constructed wetlands, environmental assessment and impact, and economics. The overall focus is to help users design and implement water management strategies and technologies to meet existing and future environmental and agricultural production goals. The guide uses a new approach that provides water management specifications and guidance based on potential economic and environmental response to proposed water management strategies.

• For over 45 years, Ohio Drainage Schools have taught land improvement contractors and agency personnel technical skills in the design and management of soil and water conservation systems, with primary focus on water table management practices.

• A set of field and watershed scale decision aids, simulation models, and expert systems are being developed to evaluate the hydrologic responses of water management systems. The foundation is the ADAPT field scale model, developed as an extension of the GLEAMS model. GLEAMS hydrology was augmented with subsurface drainage, infiltration, snowmelt and macropore flow algorithms. ADAPT gives daily estimates for pesticides and nutrients in subsurface drainage as well as the normal GLEAMS output. The model has been evaluated with data from Ohio and North Carolina, providing good predictions of runoff, drainage and water table changes. ADAPT predicts water table changes similarly to the models DRAINMOD, SWATREN, and PREFLO. Model enhancements include multimedia capabilities, a decision support system, expert knowledge databases, and an expert system. ADAPT is also being linked to the soybean model SOYGRO as part of a multi-institutional project lead by the University of Florida and funded by the United Soybean Board.

• Multifaceted agricultural water management research is underway at the Piketon Research and Extension Center (PREC) in Southern Ohio. In addition to the subirrigation/controlled drainage work, researchers are studying nitrogen management and drainage strategies for microirrigated blueberry, melon and pepper production, and the impact of controlled drainage on corn and soybean yields.