Submitted to: North Central Weed Science Society US Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: December 16, 1999
Publication Date: N/A
Technical Abstract: Soil disturbance is one of the most influential cultural practices that affect weed population dynamics. Observations have shown that considerable weed emergence can occur outside the crop growing season in the corn belt. Emergence outside of the crop growing season has the potential to reduce the weed seedbank and increase soil cover via weed growth. The objective of this research was to evaluate the potential of timing shallow tillage t stimulate weed emergence outside of the crop growing season. A study was established in the fall of 1998 in Boone County, IA. The study was conducted in a complete randomized block design with four replications and nine tillage timings. The timing of the first four treatments (fall treatments) was from soybean leaf drop to soil freeze. The remaining five treatments (spring treatments) were applied based on growing degree days prior to planting corn. Soil disturbance in the spring resulted in higher weed emergence and populations after corn planting compared to fall tillag treatments. Giant foxtail, Pennsylvania smartweed, and total weed biomass were greater in spring tilled treatments, while common lambsquarters and common waterhemp biomass were unaffected by tillage timing. While corn yield did not statistically differ between treatments, there was a trend toward decreasing yield as tillage occurred later in the spring. Spring tillage resulted in greater total emergence from the seedbank. Although this may play a role in initial seedbank reduction, spring tillage also resulted in higher 72 DAP weed populations, which would return more seed to the seedbank. This study indicates that maximum expression from the seedbank will result from tillage as early as possible in the spring accompanied by control at or before planting.