Tillage effects on soil physical properties, weed seed distribution in soil and shifts in species
Purissimo, Claudio
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https://hdl.handle.net/2142/20754
Description
Title
Tillage effects on soil physical properties, weed seed distribution in soil and shifts in species
Author(s)
Purissimo, Claudio
Issue Date
1996
Doctoral Committee Chair(s)
Wax, Loyd M.
Department of Study
Crop Sciences
Discipline
Crop Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Agronomy
Agriculture, Soil Science
Language
eng
Abstract
A tillage experiment established in the fall of 1986 in a Thorp silt loam was used to conduct a study on how long-term tillage systems affect soil strength, bulk density, soil water characteristics, weed seed distribution in soil, and shifts in species. The experiment included a corn-soybean rotation with both crop grown each year. For this study, only the corn crop was considered. The tillage systems for corn consisted of fall chisel plow followed by spring disk and field cultivate (CDFC), spring field cultivate (FC) and no-tillage (NT) prior to planting corn. Tillage system did not significantly influence soil strength in the deeper soil zones. Compared to CDFC and FC, long-term NT resulted in higher soil density at depths close to the soil surface, as confirmed by its higher soil strength and bulk density. Nonetheless, higher water holding capacity and volumetric water content were observed with NT. The soil seed bank contained four monocotyledonous and twenty dicotyledonous weed species. Across all tillage systems, the high number of dicotyledonous species observed in the soil seed bank were not expressed as flora present late in the season. Conversely, a consistent relationship between giant foxtail presence in the soil seed bank and observed weed flora was found. The vertical distribution in the weed seed bank showed a distinct relationship between giant foxtail seeds and shallow depths with NT. On a volume basis, 51% of the giant foxtail seeds were concentrated in the top 1 cm of soil with NT, 78% in the top 2 cm, and 92% in the top 3 cm. Concentration of seeds near soil surface with NT is related to the absence of soil disturbance. With CDFC, giant foxtail seeds were uniformly distributed in depth range studied, which may be attributed to the physical displacement of the seeds by the action of tillage implements. High giant foxtail population was significantly associated with the NT system, with more than 85% of the total weed population in the untreated check plots being represented by that species. Weed seed bank was a reliable indicator of the giant foxtail infestations late in the season, but was unreliable for the other species.
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