Original Articles

Importance of selected soil properties on the bioactivity of alachlor and metolachlor

Published in: South African Journal of Plant and Soil
Volume 6, issue 2, 1989 , pages: 120–123
DOI: 10.1080/02571862.1989.10634494
Author(s): C.F. ReinhardtDepartment of Plant Production, Republic of South Africa, P.C. NelDepartment of Plant Production, Republic of South Africa


Bioassays with grain sorghum (Sorghum bicolor L. Moench) cultivar NK222 were conducted in a glasshouse. Thirty-four natural soils were used in each of two experiments with alachlor [2-chloro-2′,6′-diethyl-N- (methoxymethyl) acetanilide] and metolachlor [2-chloro-6′-ethyl-N-(2-methoxy-1-methylethyl)acet-otoluidide] respectively. Linear regression analyses were performed to determine the importance of certain soil properties in the prediction of herbicide bioactivity. The order of importance for alachlor bioactivity was as follows: % C > clay % ≥ CEC P reversion ≥ soil pH; and for metolachlor: % C > clay % 3 CEC > soil pH > P reversion. Inclusion of either clay content or P reversion with % C in multiple regression equations significantly increased the predictability of alachlor and metolachlor bioactivity. Organic matter content affected alachlor and metolachlor phytotoxicity, despite the relatively low organic matter levels generally found in South African soils.

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