Applicability of zeolites in potassium and nitrate retention in different soil types

Environmental protection and sustainable agricultural production require the use of inexpensive and environmentally acceptable soil supplements. Objectives of this study were to investigate the influence of the addition of the natural zeolite – clinoptilolite (NZ) and its iron(III)-modified form (FeZ) on the potassium and nitrate leaching from sandy, silty loam and silty clay soils. The zeolites were added in two amounts: 0.5 (FeZ) and 1.0 wt. % (NZ and FeZ). The experiments were carried out in columns organized in eight experimental systems containing unamended (control specimens) and amended soils. The concentration of K+ and NO3–N in the leachates was monitored during 7 days. The obtained results indicate that the K+ and NO3–N leaching mainly depends on the soil type and pH of the soil. The NZ and FeZ addition has the highest impact on the K+ retention in the acidic sandy soil. The highest NO3–N retention is obtained with FeZ in acidic silty loam soil. The K+ leaching kinetics for all the studied soils follow the Avrami kinetics model with the parameter n < 1. This study demonstrates that NZ and FeZ can be a good soil supplement for the K+ retention for all studied soils and in the NO3–N retention for silty loam and silty clay soils. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172018]