Long-Term Tillage Effects on Seed Banks in Three Ohio Soils

Abstract

Soils from long-term tillage plots at three locations in Ohio were sampled to determine composition and size of weed seed banks following 25 yr of continuous no-tillage, minimum-tillage, or conventional-tillage corn production. The same herbicide was applied across tillage treatments within each year and an untreated permanent grass sod was sampled for comparison. Seed numbers to a 15-cm depth were highest in the no-tillage treatment in the Crosby silt loam (77 800 m–2) and Wooster silt loam (8400 m–2) soils and in the grass sod (7400 m–2) in a Hoytville silty clay loam soil. Lowest seed numbers were found in conventional-tillage plots in the Wooster soil (400 m–2) and in minimum-tillage plots in the Crosby (2200 m–2) and Hoytville (400 m–2) soils. Concentration of seeds decreased with depth but the effect of tillage on seed depth was not consistent among soil types. Number of weed species was highest in permanent grass sod (10 to 18) and decreased as soil disturbance increased; weed populations were lowest in conventional tillage in the Hoytville soil. Common lambsquarters, pigweeds, and fall panicum were the most commonly found seeds in all soils. Diversity indices indicated that increased soil disturbance resulted in a decrease in species diversity. Weed populations the summer following soil sampling included common lambsquarters, pigweeds, fall panicum, and several species not detected in the seed bank.

Management of weed emergence and weed seed bank in response to different tillage, cropping systems and selected soil properties

“…We propose the use of the weed seed bank as one early warning tool, which, well-managed, could help to prevent weed species dominance, and may maintain the sustainability of the agro system. Large differences in frequency of species within seed banks have been reported in surveys of soils differing in texture and organic matter (Cardina et al, 1991;Andreasen et al, 1991;Pareja et al, 1985). We suggest interrupting the dormancy of weed seed species present in the soil seed bank, as a way of avoiding the problem of single species dominance.…”

Weed emergence as influenced by soil moisture and air temperature

“…Thus, the number of weed plants in a cultivated Weld varies from year to year and depends on the history of the Weld, mainly the preceding crop, as mentioned by Locke et al (2002) and Shrestha et al (2002) and the weed infestation in the previous years. As mentioned by Cardina et al (1991), Yenish et al (1992, Forcella (1997), Grundy et al (1999) and Grundy and Mead (2000), the main source of weed Xora in crops is the seed bank, mainly that located within the topsoil layer, with the Wrst 2-3 cm being decisive (Melander 1994) for the potential plant density. Nevertheless, it may be necessary to consider deeper soil layer in order to achieve the potential population density, particularly for dicotyledons.…”

Effect of Different Levels of Wheat Straw Soil Surface Coverage on Weed Flora in Vicia faba Crops

“…The diversity index proposed by Shannon‐Weiner was found to be useful to assess the shift in the weed population caused by changes in cultural practices (Cardina et al. 1991).…”