Tillage Effects on Seed Distribution and Common Milkweed (Asclepias syriaca) Establishment

Abstract

Soil profile distribution of a single simulated seed dispersal event after tillage followed a nonlinear model. Approximately 40% of recovered simulated seed were found within 4 cm of the surface following chisel plowing and disking, and density declined steadily with depth to 20 cm. Moldboard plowing placed 50 to 60% of simulated seed to a depth of 11 to 16 cm. Simulated seed were evenly distributed to 8 cm depth by disking and did not differ regardless of whether plots were chisel or moldboard plowed prior to seed dispersal. More than 90% of seed remained within 2 cm of the surface with no-tillage. Simulated seed distribution was the same after a tillage rotation of chisel plowing, disking, moldboard plowing, and disking regardless if the dispersal event occurred prior to chisel or moldboard plowing. Two years of the tillage rotation and two dispersal events resulted in a distribution pattern greatly influenced by the most recent major tillage of chisel or moldboard plowing. Seedling emergence of common milkweed averaged 80% for seed buried 0.5 to 4 cm deep and emergence was negligible for seed on the surface or buried 7 cm in soil in pots in a growth chamber.

Germination response of invasive plants to soil burial depth and litter accumulation is species specific

“…Regarding Asclepias syriaca, Yenish, Fry, Durgan, & Wyse (1996) found that soil burial up to 2 cm did not affect its emergence, which is in accordance with our results. Our findings for the two Bromus species were quite similar; neither soil burial nor litter cover had a significant effect on their germination success.…”

Occasional mouldboard ploughing slows evolution of resistance and reduces long-term weed populations in no-till systems

“…There is contradictory empirical evidence on the distribution of weed seeds after MB ploughing with some data showing the main part of the seed bank placed near the furrow bottom (Van Esso et al, 1986;Cousens and Moss, 1990), while other data shows a more even distribution with a maximum in the centre of the ploughed layer (Staricka et al, 1990;Yenish et al, 1996;Gruber et al, 2010). Some farmers use a skim-coulter with the MB and this has been shown to be effective in deep burial of seeds (Roger-Estrade et al, 2001).…”

“…Some farmers use a skim-coulter with the MB and this has been shown to be effective in deep burial of seeds (Roger-Estrade et al, 2001). Most seeds reside in the top few cm of soil after years of NT (Yenish et al, 1996) and use of the skim-coulter in this situation will increase the seed burial efficacy of MB, by placing topsoil, with the weed seeds, at the bottom of the furrow. Nonetheless, the burial efficacy of 'surface' seeds (0-5 cm) with the MB can vary from 50% to 99% (Colbach et al, 2000;Roger-Estrade et al, 2001;Mohler et al, 2006).…”

Influence of Winter Seed Position and Recovery Date on Hairy Nightshade (Solanum sarrachoides) Recruitment and Seed Germination, Dormancy, and Mortality

“…The choice of tillage system influences the vertical distribution of seeds in the soil and the age of the seed population in the emergence zone (Mohler 1993;Yenish et al 1996). Moldboard plowing brings previously buried seeds to the soil surface and buries recently produced seeds.…”