Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 28, 2000
Publication Date: N/A
Technical Abstract: Conversion of some annual crop land to perennial crops may be an effective approach on farms where current management is degrading surface and ground water quality. Benefits of including perennial forages in rotation with annual crops are many. Higher water use and nitrate uptake capacity compared with annual crops decreases nitrate leaching losses to ground water and tile drains. Because of this, perennial forages also offer an excellent option for in-season manure applications and can help clean up nitrate-impacted soil and ground water by yielding high-protein forage. We predicted the impact of growing alfalfa compared with corn in two areas of Minnesota using a simulation model (GLEAMS) in conjunction with historical weather and soil information, and included the option of reducing fertilizer N on the corn. Nitrate losses on fine-textured soils generally was small under all conditions. As expected, wet years increased the risk of nitrate leaching, and leaching was highest on sandy soils. Reducing fertilizer N from 200 to 150 kg/ha was marginally effective in limiting nitrate leaching, but corn yield losses occurred in some years. On sandy soil in normal rainfall years, predicted nitrate losses were reduced 80% by growing alfalfa in place of corn. The land manager needs to focus on those portions of the landscape that serve as source areas of the pollutant in question. The flexibility of converting some annual crop land to a perennial forage depends on many factors, including availability of equipment, management skills, and presence of a market or use for the product. This concept can be applied to forage crops, shrubs, trees, and non-harvested perennials, such as switchgrass.