Looking for agricultural water quality protection practices: Denitrifying bioreactors

Abstract

Water quality challenges at local, regional, and national scales have led to increasing pressure to reduce nutrient exports from agricultural land to meet nutrient reduction goals and strategies. Considerable effort and attention have been given to improvements in in-field nutrient management, including 4R (Right source, Right rate, Right time, and Right place) nutrient stewardship. Differences in precipitation and mineralization rates of organic nitrogen (N) combined with the solubility and mobility of nitrate-nitrogen (NO3-N) make it such that in-field nutrient management practices on their own will not be sufficient to meet N reduction goals for challenges such as reducing the Gulf of Mexico hypoxic zone. Cover cropping is another practice that has been increasing in use for nutrient sequestration, erosion control, and soil health benefits. Cover crops will be critical for meeting nutrient reduction goals. However, weather variability and challenges in implementing cover crops in annual row crop systems can limit their performance for NO3 loss reduction, particularly in more northern regions. Additional practices beyond in-field nutrient management and cover crops will, therefore, be needed to meet nutrient reduction goals.