Enzyme kinetics characteristics of soil in the reclaimed homestead land on Loess Plateau

【Objective】 The objective of this study was to clarify kinetics characteristics of land soil enzyme affected by different fertilizing measures,and develop the reclamation fertilization system.【Method】 The field experiments with 6 fertilizing treatments(no fertilizer,fertilizer,compound fertilizer,compound fertilizer+bacterial manure,organic fertilizer,organic fertilizer+bacterial manure)were conducted to study the kinetics characteristics(Km,Vmax and Vmax/Km)of soil invertase,urease,and alkaline phosphatase in the Changwu County,Shaanxi Province.【Result】 Compared with the initial soil samples,chemical fertilizer reduced Vmax of soil urease and Vmax and Vmax/Km of phosphatase and compound fertilizer reduced Vmax/Km of urease.Compound fertilizer combined with bacterial manure reduced Vmax and Vmax/Km of urease as well as Vmax and Vmax/Km of phosphatase,while organic fertilizer combined with bacterial manure and organic fertilizer increased Vmax and Vmax/Km of invertase,urease and phosphatase.Correlation and principal component analysis showed that Vmax of invertase,Km and Vmax of urease,Vmax of phosphatase were important factors for evaluation of soil fertility.【Conclusion】 The research showed that single organic fertilizer or combined with bacterial manure was a rational fertilization to improve fertility of the homestead land soil on Loess Plateau.