Effects of zeolite application on rice yield, nitrogen recovery, and nitrogen use efficiency

The unique cation exchange, adsorption, hydration-dehydration, and catalytic properties of natural zeolites and their abundance have promoted their use in a wide variety of agricultural processes as soil amendments, slow-release fertilizers, and other materials. To investigate the feasibility of using a natural clinoptilolite to enhance rice grain yield, nitrogen (N) recovery and N use efficiency, an experiment was conducted in a coarse-textured rice field in the Guilan province of Iran. Three levels of 8, 16, or 24 tons of zeolite ha(-1) were incorporated into the soil with and without 60 kgN ha(-1) as urea, and their effects on the grain and straw yields, available K, apparent N recovery, N use efficiency, and some soil properties were determined. Results indicated a significant positive effect of treatments on the grain yield, straw, and tiller numbers of rice. All levels of zeolite with N showed a significant increase in grain yield compared with 60 kg N ha(-1) and control treatment. Zeolite application also increased soil-available potassium and its uptake by rice straw significantly. The lowest apparent N recovery (40%) was obtained from application of 60 kg N ha(-1), whereas application of 8 or 16 tons zeolite ha(-1) increased apparent N recovery up to 65%. Nitrogen use efficiency was also improved.