title: Effect of dairy manure rate and the stabilization time of amended soils on atrazine degradation.
abstract: The application rate of liquid cow manure (LCM) in the field and the stabilization time of amended soils before application of pre-plant herbicides are factors that determine their efficiency. This study includes evaluation of residual atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) in soil and amended soils with equivalent rate of 100,000; 200,000; and 300,000 L ha(-1) of LCM and the effect of pre-incubation time of amended soils on atrazine degradation. The study was carried out under controlled conditions using an Andisol with previous historical application of atrazine. The respiratory activity and fluorescein diacetate (FDA) studies indicated that the time necessary for stabilization of amended soils is over 20-30 d. During the measurement of respiratory and FDA activity, no significant differences were observed when atrazine was applied. The half-life of atrazine ranged from 5 to 8d and the relative distribution of degradation products seem to be affected by the application of LCM. The pre-incubation time of amended soil and LCM dose would not affect atrazine degradation rate, when the soil has a history of herbicide application. However, repeated applications of LCM in a long period of time could change the soil pH and increase the content of dissolved organic carbon (DOC) which could further contribute to a faster degradation of atrazine. Both effects would reduce the effectiveness of atrazine in weed control.
authors.affiliation: Departamento de Ciencias Químicas, Universidad de La Frontera, Casilla 54-D, Temuco, Chile.
authors.forename: Paula
authors.initials: P
authors.lastname: Aguilera
authors.forename: Gabriela
authors.initials: G
authors.lastname: Briceño
authors.forename: Maribel
authors.initials: M
authors.lastname: Candia
authors.forename: Maria de la Luz
authors.initials: Mde L
authors.lastname: Mora
authors.forename: Rolando
authors.initials: R
authors.lastname: Demanet
authors.forename: Graciela
authors.initials: G
authors.lastname: Palma
mesh_terms: D000818:Animals; D001280:Atrazine / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002417:Cattle; D004784:Environmental Monitoring; D005452:Fluoresceins / Q000378:metabolism; D006207:Half-Life; D006540:Herbicides / Q000378:metabolism*; D008372:Manure; D012987:Soil; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism*; D013997:Time Factors
chemical_list: D005452:Fluoresceins; D006540:Herbicides; D008372:Manure; D012987:Soil; D012989:Soil Pollutants; D001280:Atrazine; C018506:diacetylfluorescein