Seasonal variations in preferential flow under corn and soybean cropping
Kamau, Peter Alfred
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https://hdl.handle.net/2142/20331
Description
Title
Seasonal variations in preferential flow under corn and soybean cropping
Author(s)
Kamau, Peter Alfred
Issue Date
1994
Doctoral Committee Chair(s)
Ellsworth, Timothy R.
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
Hydrology
Environmental Sciences
Language
eng
Abstract
The intensive use of agrichemicals to achieve greater crop production has increased the potential for surface and groundwater contamination. As a consequence, there is a need for regulations and improved management strategies relative to the use of agrichemicals. An understanding of the complex mechanisms and processes which control the environmental fate of these chemicals under current agricultural cropping systems is essential in order to make the proper management decisions. At the present time, knowledge of spatial and temporal variations in preferential flow under different cropping systems and tillage practices during the growing season is lacking, which has complicated the making of sound and reasonable regulatory decisions on the use of agrichemicals. In order to investigate the effect of tillage, cropping and row position on chemical movement through the soil, bromide and chloride, which are regarded as conservative tracers of nitrate, and nitrate solutions were applied on 2 m x 2 m plots which were randomly selected on two different dates (during the vegetative and the reproductive stages of the corn cropping). Core samples (7.6 or 11.4 cm diameter) to a maximum depth of 1.5 m were collected 4 days after chemical application, divided into 5- or 10-cm sections and analyzed for the applied tracer chemicals and nitrate. Infiltration rates were also measured on five and four different dates between mid May and the end of October in 1992 and 1993, respectively. Results from this study indicate that the depth of leaching of the surface-applied chemicals is a function of the application method (spraying or flooding) and the location of chemical placement (between or in row). However, differences between tillage practices and cropping systems were not significant in terms of chemical transport and leaching. The temporal variations in the hydraulic properties are significant, especially under corn cropping, and differences in infiltration rates measured in between row (BR) and in-row (IR) positions were also significantly different under both corn and soybean cropping.
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