Field experiments were conducted in 1991, 1992, and 1993 to evaluate the dissipation and carryover potential of atrazine from starch-encapsulated (SE) and commercial formulations (CF). Formulation was not a significant factor in atrazine dissipation at any application rate. The dissipation time required to reach one-half of the original concentration (DT50) was measured for each formulation. The atrazine DT50 combined over all years (1991 to 1993) and rates (1.1 to 3.4 kg ai ha−1) was 7 wk for the CF, 10.3 wk for the SE large particles (0.85 to 1.4 mm), and 8.2 wk for the SE small (0.425 to 0.85 mm). Oat injury in the spring of 1992 from all rates of both SE formulations applied in 1991 was greater than that from the CF formulation. Increased oat injury from SE formulations was attributed to more atrazine present in the top 0 to 8 cm of soil compared to that for the CF. Despite significant oat injury from the 1991 application, no injury was observed on soybeans planted in 1992. Soybeans planted in 1993 and 1994 also showed no injury from the respective applications. These findings suggest that the potential for atrazine carryover from starch-encapsulated formulations was not greater than that from the commercial formulation.

Cover crop systems were investigated in 2004 and 2005 for their effects on the activity-density (a function of movement and density) of a promising group of weed biocontrol organisms, the ground beetles collectively known as carabids, with particular emphasis on a beneficial carabid species Harpalus rufipes DeGeer. Marked H. rufipes released into pea/oat–rye/vetch cover crop plots were more than twice as likely to be recaptured within the same plots as beetles released in nonvegetated fallow plots (18 and 8%, respectively). Marked beetles released into fallow plots were more than twice as likely to leave their plots and be recaptured in pea/oat–rye/vetch plots as vice versa (13 vs. 5%), indicating a clear preference for habitat with vegetative cover. Overall recapture rates were not different between treatments. Unmarked H. rufipes activity-density was also higher in pea/oat–rye/vetch compared to fallow plots. Additionally, five cover crop systems, including the fallow and pea/oat–rye/vetch treatments, and two residue management methods (conventional and zone tillage) were investigated from June to August in 2005 for their effects on H. rufipes activity-density. Corn was planted in 2005 into residues of the five cover crop systems grown in 2004. H. rufipes activity-density was higher in zone and conventionally tilled corn planted in pea/oat–rye/vetch residues and conventionally tilled corn planted in red clover/oat residues than in any other cover crop and residue management combination. Pea/oat–rye/vetch cover crop systems are apparently beneficial for H. rufipes during the cover crop year as well as in subsequent crops planted into this cover crop's residues. This system was not the least disturbed system but, based on the number of tillage events, represented a medium level of disturbance among the various systems. Thus, some level of disturbance might be beneficial for H. rufipes, but how and when that soil disturbance occurs requires further research to determine the best means of conserving this species.