Master of Science (MS)
Plant, Environmental Management and Soil Sciences
Best management practices are used by agricultural producers to control or reduce the transport and generation of contaminants to the water resources of the state, ultimately increasing the quality of surface and ground waters. One such practice is residue management used during sugarcane production. The impact of sugarcane residue may have on the retention and release of two herbicides namely; atrazine and metribuzin was the focus of this study is studied. Adsorption-desorption and transport behavior of herbicides are important processes that influence the amount of herbicide retained by the soil or crop residue and that which is susceptible to runoff or movement within the soil profile. Kinetic batch experiments were used to study the adsorption-desorption behavior of atrazine and metribuzin in sugarcane mulch residue and two surface soils. Atrazine retention was consistently stronger than metribuzin for both sugarcane residue and surface soils. To describe the retention of atrazine and metribuzin by the residue as it ages and across growing seasons, only one value (Kd) was needed for each herbicide, and this value is an order of magnitude greater then those determined for surface soils. Miscible displacement experiments under steady flow conditions were also carried out to examine the mobility of the metribuzin within soils. In addition field studies quantified the decay of sugarcane residue in the field following combine harvest. Amounts of residue cover varied with the growing season and variety. Half-lives of 126 to 171 days were determined for sugarcane residue as it remains in the field. With residue age mass decreases leaving greater percentages of more recalcitrant residue such as lignin. Fiber analysis identified these changes, there were no obvious relationships between herbicide retention distribution coefficients and percentage of lignin on a mass basis.
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Naquin, Brian J., "Herbicide retention as affected by sugarcane mulch residue" (2005). LSU Master's Theses. 3120.
H. Magdi Selim