Effects of interface barrier materials on rice yield, nitrogen use efficiency, and NH₃ volatilization

NH₃ volatilization emissions cause significant nitrogen losses in rice fields. Effective control of NH₃ volatilization emissions in rice fields is critical to increase rice yield and nitrogen use efficiency. Interface barrier materials are environmental-friendly and low cost, making them suitable as a completely different method of reducing NH₃ volatilization. This study therefore explored the impacts of interface barrier materials on rice yield and nitrogen use efficiency, which may help to achieve rice yields with low costs and reduced environmental pollution. In this study, three interface barrier materials including two surface molecular film materials:polylactic acid (PLA) and lecithin (LEC) materials were formulated as surface molecular film materials and were sprayed evenly on the field after fertilization at the basal, tillering, and earing rice stages. Rice bran was also evenly spread over the field after fertilization on the same day. The rice yield and yield composition, pH and nitrogen concentration in paddy surface water, soil nitrogen content, nitrogen use efficiency and NH₃ volatilization were investigated. The experiment involved five treatments:CK (no N fertilizer), CKU (only urea), RB (rice bran + urea), PLA (polylactic acid + urea), and LEC (lecithin + urea). Fertilizer additions and field management practices remained the same across all treatments. The results showed that the RB, PLA and LEC treatments significantly increased rice yield compared to CKU treatment by 13.0%, 21.0%, and 24.1%, respectively. The nitrogen fertilizer utilization rate of LEC treatment significantly increased by 19.0% compared to the CKU. The RB treatment significantly increased yield by 13.0% compared to CKU, but did not significantly affect the nitrogen utilization rate. The addition of RB and PLA significantly increased the effective spike number in rice, but the LEC treatment produced no significant difference in this variable. The number of grains and the seed setting rate did not differ significantly under the CKU from their interface barrier materials added. The addition of interface barrier materials reduced NH₃ volatilization by 12.3%-19.9% in comparison with CKU, and the PLA treatment significantly reduced NH₃ volatilization by 19.9%, and performed best. It was followed by the LEC treatment with a reduction of 14.3%. The reductions in NH₃ volatilization may be related to the changes in surface water pH, NH₄⁺-N concentration, and soil NH₄⁺-N content caused by the addition of interface barrier materials. Compared to the CKU treatment, all treatments increased the NH₄⁺-N concentration but lowered the pH in surface water, especially during the tillering stage. The soil NH₄⁺-N content was also improved in the PLA treatment. This study shows that the application of interface barrier materials in rice fields is a feasible technical approach to reduce NH₃ volatilization and increase rice yield and nitrogen use efficiency.