title: Spatial distribution of diuron sorption affinity as affected by soil, terrain and management practices in an intensively managed apple orchard.
abstract: We investigated how the sorption affinity of diuron (3'-(3,4-dichlorophenyl)-1,1-dimenthyl-urea), a moderately hydrophobic herbicide, is affected by soil properties, topography and management practices in an intensively managed orchard system. Soil-landscape analysis was carried out in an apple orchard which had a strong texture contrast soil and a landform with relief difference of 50 m. Diuron sorption (K(d)) affinity was successfully predicted (R(2)=0.79; p<0.001) using a mid-infrared - partial least squares model and calibrated against measured data using a conventional batch sorption technique. Soil and terrain properties explained 75% of the variance of diuron K(d) with TOC, pH(w), slope and WI as key variables. Mean diuron K(d) values were also significantly different (p<0.05) between alley and tree line and between the different management zones. Soil in the tree line generally had lower sorption capacity for diuron than soil in the alleys. Younger stands, which were found to have lower TOC than in the older stands, also had lower diuron K(d) values. In intensively managed orchards, sorption affinity of pesticides to soils was not only affected by soil properties and terrain attributes but also by management regime.
authors.affiliation: School of Earth and Environmental Sciences, University of Adelaide, Urrbrae, 5064 South Australia, Australia.
authors.forename: Beng P
authors.initials: BP
authors.lastname: Umali
authors.forename: Danielle P
authors.initials: DP
authors.lastname: Oliver
authors.forename: Bertram
authors.initials: B
authors.lastname: Ostendorf
authors.forename: Sean
authors.initials: S
authors.lastname: Forrester
authors.forename: David J
authors.initials: DJ
authors.lastname: Chittleborough
authors.forename: John L
authors.initials: JL
authors.lastname: Hutson
authors.forename: Rai S
authors.initials: RS
authors.lastname: Kookana
mesh_terms: D018556:Crops, Agricultural; D004237:Diuron / Q000378:metabolism*; D027845:Malus; D012989:Soil Pollutants / Q000378:metabolism*
chemical_list: D012989:Soil Pollutants; D004237:Diuron