|J M NOVAK|
|D W WATTS|
|P G HUNT|
Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/4/1996
Publication Date: N/A
Interpretive Summary: Farmers typically plow soil to prepare a seed bed for planting. Plowing mixes plant residue into the soil, reduces weed populations, and recycles some plant nutrients. Plowing can create increased rates of soil erosion, which reduces the amount of productive soil. Another tillage practice called conservation tillage, where the soil is not plowed, typically lowers sthe amount of soil lost to erosion. However, conservation tillage requires that farmers use pesticides to control weeds and insects. Our research evaluated the ability of soils that were farmed using either traditional plowing or conservation tillage to sorb and retain pesticides. Comparing both tillage systems, soil under conservation tillage had a higher ability to sorb pesticides than plowed soils.
Technical Abstract: Conservation tillage (CnT) management practices are known to increase levels of soil organic matter (SOM), especially in the top few centimeters of southeastern Coastal Plain soils. We hypothesize that herbicide sorption will be highest in this SOM enriched zone of CnT systems when compared to sorption at a similar depth in conventional tillage (CT) systems. We evaluated the influence of long-term (15 yrs) tillage practices and CnT and CT on sorption of atrazine (ATR) and fluometuron (FLMT) in plots of Norfolk loamy sand soil. Bulk (0-15 cm) and five equal incremental soil samples to a 15-cm depth were collected from 10 CnT and 10 CT plots, and the ATR and FLMT sorption coefficients (Kd) were measured. Testing tillage effects by soil depth revealed that significantly higher herbicide Kd values and soil organic carbon (SOC) contents occurred in the CnT 0 to 3-cm samples. For the rest of the samples, herbicide Kd values decreased with depth with no significant differences between tillages. A highly significant linear regression relationship between SOC and herbicide Kd values was found. Our results suggest that the quantity of SOC is an important component influencing ATR and FLMT sorption in the first 3 cm of the surface soil layer in our tillage plots.