Predicting seedling emergence of velvetleaf (Abutilon theophrasti), large crabgrass (Digitaria sanguinalis), jimsonweed (Daturastramonium) and black nightshade (Solanum nigrum) in different burial depths of soil

Knowledge of emergence ability of weed species from different soil depths is important value in weed management strategies especially at different tillage systems. A greenhouse experiment was conducted to study the effect of soil burial depth on seedling emergence of velvetleaf, large crab grass, jimsonweed and black nightshade. Seed portions of the species were buried in pots outdoors, at the depths of 0, 2, 4, 6, 8, and 10 cm, in a Randomized Completely Block Design with four replications on May 2015. Soil depth had different effect on seedling emergence of weeds species but decreasing emergence with increasing soil depth was observed in all species. At 10 cm, only velvetleaf emerged albeit only in limited numbers among weeds species. Based on parameters of sigmoidal regression model, X50 (depth at which the number of emerged seedlings was halved) varied by weed species. These depths were 7.31, 4.02, 5.44 and 5.40 cm for velvetleaf, large crab grass, jimsonweed and black nightshade, respectively. Information gained in this study will contribute to an integrated control program for these weeds. Deep tillage that will bury weed seed below 6 cm or greater is a possible weed management option for farmers.