根据贝塔朗菲系统自生长的微分方程 ,可建立表征土壤生态系统动态变化的动力学方程 :dx/dt =(f-s)x-bx2 ,t为时间 ,x为土壤微生物数量 ,f为其繁殖系数 ,s为死亡系数 ,b为饱和系数 .其解 (1)x=x0 e(f-s)t,(2 )x =(f -s) /b.方程 (1)表明 ,如s>f,则当t→∞时 ,x→ 0 ,表明土壤生态系统处于热力学分支 ,将向退化的方向发展 ;方程 (2 )表明 ,如f>s ,其临界点x =(f -s) /b ,如x>x ,则表明土壤生态系统处于耗散结构分支 ,将向进化的方向演替 According to the self-growing differential equations of the Bertalanffine system, a kinetic equation can be established to characterize the dynamic changes of the soil ecosystem: dx / dt = (fs) x-bx2, where t is time, x is the number of soil microorganisms and f is its coefficient of propagation (1) x = x0 e (fs) t, (2) x = (f -s) / b. Equation (1) shows that if s> f then When t → ∞, x → 0, indicating that the soil ecosystem is in the thermodynamic branch, will develop toward degradation; Equation (2) shows that the critical point x = (f -s) / b as f> x> x, then the soil ecosystem is in the branch of dissipative structure and will be evolved in the direction of evolution