Improving Agricultural Sustainability through Drainage Water Management Practices

View the project final report

• 2007 annual report
• 2008 annual report

Commodities

• Agronomic: corn, soybeans

Practices

• Crop Production: conservation tillage
• Education and Training: extension, technical assistance
• Farm Business Management: budgets/cost and returns
• Natural Resources/Environment: riparian buffers
• Pest Management: chemical control
• Sustainable Communities: sustainability measures

Drainage water management can reduce nitrate loss from drained fields while maintaining crop production.

This project measured the impact of drainage water management on drain flow and water table depth on three Indiana farms using the paired watershed approach.

Drainage water management was found to reduce drainage outflow during both summer and winter treatment, and maintain water table depth at higher levels than the conventionally-drained field. The impact of drainage water management on flow and water table depth were greater during the winter treatment period compared to the summer period.

Introduction:

Agricultural drainage plays a vital role in the cropping systems in the Midwest; however, conventionally-managed drainage has been found to increase nitrate loss through enhanced leaching of the soil profile(Tomer et al., 2003). Subsurface drainage is used to improve soil aeration, lower surface runoff through increased infiltration, and therefore improve crop growth and yield, but has been reported as a major source of nitrate loading to surface water in the Mississippi River Basin (Burkhart and James, 1999; Randall and Goss, 2001).

A number of practices are being studied that have potential to reduce nitrate losses from subsurface tile drains. Some of these include reduced fertilizer applications, cover and perennial crops, biofilters, and wetlands (e.g.`, Dinnes et al., 2002; Randall and Mulla, 2001). Drainage water management (also known as controlled drainage) is one of the practices that show great promise for Midwest flat land, because it has the potential to reduce nitrate loss from drained fields while maintaining drainage intensity critical to crop growth. It works by raising the water table level at which drainage occurs by raising the effective height of the drain outlet, which reduces drainage and consequently nitrate loss. A few studies in the Midwest (Drury et al., 1996; Fausey et al., 2004) have shown the potential for reducing nitrate loss under these conditions. On-farm studies are needed to test the practice under a greater variety of conditions, and better understand how the practice impacts the farming operation.

The field-scale research we have conducted with funds from the SARE grant was part of a larger project evaluating the impacts of drainage water management on corn and soybean cropping systems, yield, economic sustainability, soil quality and nitrate losses at the watershed scale. The larger project includes evaluating drainage water management potential impacts on soil physical properties, earthworms, plant growth, plant nitrogen content, yield and profitability. The focus of the SARE-funded project was on assessing the impact of this practice on water table and drain flow, through paired field on-farm trials of conventional and managed drainage on three Indiana fields.

The main objective of this project was to assess the impact of drainage water management on reducing tile outflow from drained fields, increasing available water and crop yield through paired-field studies on three farms in Indiana.

We also formulated intermediate and long-term desired outcomes, although they were not expected to be accomplished during the course of the project. The desired intermediate-term outcomes will:

1. Enable farmers to make more informed decisions on whether or not the adoption of the practice would be profitable for them, and

2. Enable federal, state, local, and non-governmental soil conservation and water quality organizations to make decisions about supporting drainage water management as a best management practice.

The desired long-term outcome is that farmers will adopt the practice (if it is determined to be successful at increasing yield, promoting improved water quality and reducing nitrate losses).