A Unified Model for the Degradation Kinetics of Pesticides Applied Continually to Soils

This paper deduces a kinetic model for microbial degradation of pesticides in soils:x=x0(M/[M-m0+m0exp(μt)])^kM/μ where x is the concentration of pestcide at time t,x0 the initial concentration of the pesticide,m0 the initial number of pesticide-degrading microogranisms,M the carrying capacity for the microorganisms,μ the specific growth rate of the microorganisms,and k the rate constant for the pesticide degradation.In periodic applications of pesticides,this model can be used to continumously describe every degradation curve.Whether a lag phase occurs or not,we can obtain the minimum residue of the pesticide(xe): xc=xdexp(-kMτ)/[1-exp(-kMτ)]where τ the regular time intervals between applications ,and xd the dosage of the pesticide.