Seventeen Years of Cropping Systems and Tillage Affect Velvetleaf (Abutilon theophrasti) Seed Longevity

Abstract

Velvetleaf is difficult to control in corn and soybean and the seed can persist in soil for many years. Seven cultural and tillage practices were established in 1974 on a site heavily infested with velvetleaf to determine the time required to eradicate velvetleaf seed from the soil. A rapid decline in velvetleaf seed population in the top 23 cm of soil occurred during the first 5 yr of this study. In the fifth year, the chemical fallow and continuous alfalfa treatments had 37 and 56% of the original velvetleaf seed population remaining, respectively. In the 17th year, soils in these treatments that had received no tillage since study initiation still contained 15 and 25% of the original velvetleaf seed population, respectively. Systems involving moldboard plowing with continuous-tillage fallow, continuous cropping of corn or oat, or an annual corn and soybean rotation had a more rapid decline in the velvetleaf seed population in soil compared to the chemical fallow and continuous alfalfa treatment. After 17 yr, soil in any system that had received at least one moldboard plowing per year still contained 1 to 3 million velvetleaf seed ha−1, which is only 0.8 to 2.5% of the initial viable seed population. Nearly 100% of the seed remaining in the soil in the 17th year for all treatments was still viable.