Increasing nitrogen use efficiency with lower nitrogen application frequencies using zeolite in rice paddy fields

Zeolite can effectively regulate the nutrient status in the root zone of crops, thereby increasing nitrogen utilization. However, there has been relatively little research conducted concerning a possible reduction in the frequency of nitrogen application due to the sustained-release properties of zeolite. In this study, 157.5 kg ha(-1) nitrogen in the form of urea fertilizer was applied at the same rale, either as a one-time application or as a 3-way split application with and without 10 t ha(-1) zeolite. The effects on rice yield, nitrogen uptake, root morphology and soil properties were evaluated in 2014 and 2015. Results showed that zeolite could enhance the biomass, leaf area index and nitrogen uptake. A higher rice grain yield and nitrogen uptake following soil treatment with zeolite could be attributed to a higher soil cation exchange capacity as well as nitrogen and potassium availability in the soil especially during the vegetative period of the rice plant. The addition of nitrogen to the soil as a one-time application or 3-way split application with 10 t ha(-1) zeolite significantly increased rice grain yield by 8.5 or 10.7% compared with nitrogen as a one-time application without zeolite. Zeolite addition greatly improved the development of root morphology and activity compared with treatments without zeolite, which contributed to additional plant growth. The addition of nitrogen to the soil with 10 t ha(-1) zeolite as a one-time application that can significantly increase nutrient retention is recommended to improve rice grain yield and decrease nitrogen application frequencies in order to lower both labour forces and energy requirements.