| Weed populations are not uniform across an agricultural field. Understanding processes contributing to spatial variability will enhance management efficiency. Plant density, emergence patterns, and heights of four common annual weed species were determined within 10 research sites within an agronomic production field. The total diversity of weed species was also determined. The locations of research sites were at summit, backslope, and toeslope landscape positions. The diversity assessment revealed more species at the toeslope than at the backslope and summit in 2000. Weed densities varied considerably across sites. Toeslope sites had the greatest densities of annual grasses, common ragweed, and common cocklebur. Emergence of many species was slower at toeslope sites indicating temporal variability of weed populations in addition to spatial variability. Weeds also grew slower at toeslope sites. Soil hydrology and associated pedogenic processes were the most likely cause of these dynamic weed population differences found within the landscape. |
