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Gewählte Doctoral Thesis:

Shady Selim (2016): HERBICIDE RETENTION AFFECTED BY SOIL MANAGEMENT PRACTICE.
Doctoral Thesis - Institut für Siedlungswasserbau, Industriewasserwirtschaft und Gewässerschutz (SIG), BOKU-Universität für Bodenkultur, pp 216. UB BOKU obvsg

Data Source: ZID Abstracts
Abstract:
Understanding adsorption-desorption behavior of pesticides are important processes that influence the amount retained by the soil and which is susceptible to runoff or movement within the soil profile. In this study, kinetic batch experiments were used to study the influence of biochar (BC) amendment, and no-tillage (NT) compared to conventional tillage (CT) practices on adsorption-desorption behavior of chloridazon (CRZ) and terbuthylazine (TBZ) in soils, also the soil factors that contribute to glyphosate (Gly) retention in soils. Modeling of these herbicides retention was carried out using different models; linear, Freundlich and multireaction (MRM) models. The results revealed that 1) The BC amended soils (1% and 3%) were approximately 5-113 and 2-16 times more effective than the BC-free soils in sorbing CRZ and TBZ, respectively. Also, the addition of BC to soils (1% and 3%) decreased desorption of CRZ and TBZ by approximately 5.9 – 0.49% and 17-1.6% of the fraction initially sorbed in both soils, respectively. 2) CRZ and TBZ sorption was higher under NT than under CT owing to higher organic carbon content. Also, desorption of CRZ and TBZ was hysteretic, and after the desorption steps, between 64-77% of the sorbed CTZ and between 45-68% of the sorbed TBZ was desorbed from CT and NT soils, respectively. 3) Sorption of Gly by all soils was nonlinear with N24 ranged from 0.49 to 0.63 and KF24 ranged from 39.8 to 178.2 L Kg-1, desorption was strongly irreversible and hysteretic in nature. After successive dilutions, the amount of Gly released ranged from 3.2% to 24.3% of the adsorbed fraction. Soil with highest Fe and Al oxides, organic matter, and clay content exhibited the strongest affinity and kinetic behavior for Gly. 4) Overall the study, sorption isotherm in the soils was better described by the Freundlich model than the linear model; moreover, MRM approach was capable of describing herbicides retention in all soils. 5) This research suggests that biochar amendment may be more effective management practice than no-tillage for immobilization of herbicide in soils, decreasing the risk of environmental contamination and human exposure via transfer in the food chain, but may affect the efficacy of soils applied herbicides.

Betreuer: Fürhacker Maria
1. Berater: Klik Andreas

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