|Lerch, Robert - Bob|
Submitted to: North American Agroforestry Conference
Publication Type: Abstract only
Publication Acceptance Date: 5/1/2003
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: A lysimeter study with six different ground covers (bare ground, orchardgrass, tall fescue, timothy, smooth bromegrass, and switchgrass) was established to evaluate the ability of forages to reduce nitrate transport. Each lysimeter received 150 mg of NO3-N and either 1500 ug of atrazine or 240 ug of isoxaflutole. The leachate from each lysimeter was collected after major rainfall events over a 25-day period. Switchgrass, tall fescue, orchardgrass, and smooth bromegrass treatments reduced nitrate transport by 98.2 to 99.7% compared to the bare ground control. Switchgrass treatments reduced PO4-P levels in leachate to the greatest extent, with reductions of 60.0% to 74.2% compared to the control. Relative to the soil NO3-N level in the control treatments, tall fescue, smooth bromegrass, switchgrass, timothy, and orchardgrass removed 91.2, 89.8, 89.3, 79.0, and 40.9% of NO3-N from soil, respectively. The herbicide treatments had no significant effect on overall nutrient removal from soil or leachate. The results of microbial denitrification work suggested that the denitrification rate was significantly enhanced by the presence of some species. For instance, denitrification capacity was found to be greatest in soil collected from switchgrass and smooth bromegrass treatments. For ATR treated lysimeters, the maximum denitrification rate strongly correlated with microbial biomass carbon of the forage treatments. However, this correlation was poor in the soil collected from Balance treated lysimeters. Based on this study, switchgrass, smooth bromegrass, and tall fescue would be suitable candidates to be incorporated into riparian buffer designs for reducing nutrient transport to groundwater.