Influence of Weed Management and Cropping Systems on Sicklepod (Cassia obtusifolia) Seed in the Soil

Abstract

Research was conducted from 1979 through 1982 in east-central Alabama to monitor changes in sicklepod (Cassia obtusifoliaL. ♯ CASOB) seed numbers in the soil under various cropping and weed management systems in soybeans [Glycine max(L.) Merr.]. Significant declines in sicklepod seed numbers were attained only when mechanical summer fallow each year prevented replenishment of seed in soil. Repeated disking favored germination and emergence of sicklepod seed and thus caused a reduction in seed numbers. Chemical summer fallow, which relied on postemergence control of emerged sicklepod, did not result in a disturbed seedbed and was less effective in reducing seed numbers. Permitting subcompetitive densities of sicklepod, 0.45 and 0.90 plants/m2, to reach maturity each year resulted in increases in seed numbers in the soil. Increases were more dramatic in conventionally planted soybeans than in no-till culture. Sicklepod produced more pods per plant in tilled culture than in no-till. Sicklepod seed distribution in the upper 30 cm of the soil was not affected by the type of primary tillage.