UTILIZATION NATURAL ZEOLITES FOR INCREASING CROP PRODUCTION IN THE UPLAND

Oleh: Suwardi, and Itsuo Goto (20000

ABSTRACT

Zeolites with unique cation-exchange, molecular sieving, and adsorption make these minerals attractive to agricultural and industrial utilization. Indonesia has more than 50 zeolite deposits and some of them have been exploited as mining materials. Some zeolite application to agricultural lands have been established, including direct application as soil amendment, mixing with chemical and organic fertilizer as slow release agent and as materials of growth media. The most important reason of zeolite application is their capability to capture ammonium ion (NH₄⁺) and availability in abandon amount as natural resources.

These experiment demonstrated the application of zeolites in single and combination with compost and calcite as soil amendment. The results showed that application of zeolites in single application increased the cation-exchange capacity (CEC) and exchangeable bases of soils when they applied to low CEC soils. Zeolites also enhanced the available P₂O₅ in the soil and the increase was higher when zeolites were combined with chicken-manure compost. The increase of the available P₂O₅ was possibly caused by indirect effect of the Ca existence in zeolites. Zeolites increased slightly the yield of soybean in Inceptisol in the first and second plantings. Increasing soybean and sorghum production ranged from 10 to 60% were caused by improvement of nitrogen and phosphorus availability in the soil due to the action of zeolites application. Among treatments, combination of zeolites-compost-calcite gave the best result. Improvement the availability of N and P in the soils influenced the N and P concentration in plants. However, zeolites application decreased the micronutrients availability of Mn and Zn. Application of zeolites, therefore should be accompanied by addition of micro nutrients to soils.