Weed emergence patterns as affected by topsoil movement within an eroded landform

Authors: Schneider, Sharon; Sutradhar, Apurba; GULDEN, ROBERT - University Of Manitoba

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/29/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Weeds interfere with crop growth, and weed management is a major consideration for farmers. Small-scale differences in weed densities, emergence timing, weed seed production, seed viability, herbicide bioavailability, and other factors complicate weed management strategies in eroded landscapes. Reversing soil erosion by replacing translocated topsoil (soil-landscape rehabilitation) is one method to improve crop productivity of severely eroded land, but bulk movement of soil changes soil properties and weed seedbanks that influence weed spatial distribution patterns, emergence and growth. We evaluated the response of weed communities to soil movement within a hilly landform. Soil-landscape rehabilitation was performed by moving 15-20 cm of accumulated topsoil from the lower slope and adding it to the upper slope positions (areas of net soil loss by erosion). Neighboring plots were left in their eroded condition. Weed density and species richness were monitored for four years. In the upper slope positions, the weed community was dominated by annual grasses, and weed abundance was highest in the most eroded landscape positions. Soil addition improved soil characteristics for crop growth but did not result in increased weed densities. The density of weeds was lower where soil was removed in the first two years after soil movement, likely through removal of weed seeds with soil. Within three years of soil movement, weed abundance and species richness were the same in areas of soil removal and no soil removal. In these experiments, movement of soil (and entrained weed seeds) within an eroded landform to improve productivity did not worsen weed issues.

Technical Abstract: Soil erosion is a major environmental issue that significantly affects soil properties, crop productivity, weed emergence patterns, and weed growth. Spatial variability in weed densities, emergence timing, weed seed production, seed viability, herbicide bioavailability, and other factors complicate weed management strategies in eroded landscapes. Reversing soil erosion by replacing translocated topsoil (soil-landscape rehabilitation) is one method to improve crop productivity of severely eroded land, but bulk movement of soil changes soil properties and weed seedbanks that influence weed spatial distribution patterns, emergence and growth. We evaluated the response of weed communities to soil movement within a hilly landform. Soil-landscape rehabilitation was performed by moving 15-20 cm of accumulated topsoil from the lower slope and adding it to the upper slope positions (areas of net soil loss by erosion). Adjacent plots were left in their eroded condition. Weed density and species richness were monitored for four years. In the upper slope positions, the weed community was dominated by annual grasses, and weed abundance was highest in the most eroded landscape positions. Soil addition improved soil characteristics for crop growth but did not result in increased weed densities. The density of weeds was lower where soil was removed in the first two years after soil movement, likely through removal of weed seeds with soil. Within three years of soil movement, weed abundance and species richness were the same in areas of soil removal and no soil removal. In these experiments, movement of soil (and entrained weed seeds) within an eroded landform to improve productivity did not exacerbate weed issues.