|HARBOURT, CHRIS - Waterborne Environmental|
|BROZ, ROBERT - University Of Missouri|
|THEVARY, TERESA - University Of Missouri|
Submitted to: American Water Resources Association Spring Specialty Conference
Publication Type: Abstract Only
Publication Acceptance Date: 11/20/2012
Publication Date: N/A
Technical Abstract: In the U.S. Corn Belt, claypan soils are vulnerable to both erosion and transport of unincorporated herbicides. Thus, there is a need to identify tillage practices that can achieve a balance between herbicide transport and soil erosion for these soils. The objectives of this research were to compare the effect of three tillage systems on sediment and atrazine transport in surface runoff for a claypan soil and to compare their agronomic utility. Tillage treatments were: 1) rotary harrow – atrazine incorporated to ~5cm (RH); 2) no-till without incorporation (NT); and 3) minimum-till - incorporated atrazine to ~10 cm (MT). Three main tillage plots were established for each of the treatments, and two sets of runoff sub-plots, with three replicates each, were established within the main plots. Runoff was generated with a rainfall simulator at an average rate of 27 mm/ h. Runoff samples were collected at unequal time intervals from 1 to 90 min after runoff initiation, and analyzed for total suspended sediment (TSS) and dissolved-phase atrazine concentrations. The RH treatment had significantly lower TSS concentrations and loads than MT, but it did not significantly increase erosion compared to NT. The RH treatment also had significantly lower atrazine concentrations and relative loads than NT, but not significantly greater atrazine transport than MT. Atrazine relative loads, as a percent of applied, were: NT, 22.2 percent; RH, 10.6 percent; and MT, 6.4 percent. The RH treatment also resulted in comparable or better yields and weed control than the other treatments. The RH treatment successfully managed the trade-off between erosion and atrazine transport for a claypan soil and can be used as a best management practice for claypan and related restrictive layer soils.