Synergistic improvement of straw decomposition and rice yield in saline sodic paddy soils by rational nitrogen application

Soil salinization poses a significant challenge to agriculture. The practice of returning straw to the field has garnered increasing attention as a sustainable method to improve salinized land. This study aimed to investigate the impact of nitrogen application rates on rice straw decomposition, rice straw nutrient release, and rice yield in saline sodic rice field conditions.

The field experiment was designed with five nitrogen (N) fertilizer rates with 0 (N0), 90 (N1), 180 (N2), 270 (N3), and 360 kg N ha⁻¹ (N4) under the condition of full return (8 t ha⁻¹) of straw from sodic-saline paddy fields, nylon mesh bag filling method was used to study the decomposition process of rice straw. The field experiment was conducted in a completely randomized design with three replications.

The results showed that the application of N fertilizer promoted the decomposition of rice straw and the release of C, N and P from the straw, but had no effect on the release of K from the straw. Compared with N0, the cumulative decomposition rates of rice straw in N1, N2, N3 and N4 treatments were significantly increased by 10.05%, 15.10%, 20.00% and 18.44%, respectively (two-year average). In addition, the highest rice yield was obtained in the N3 treatment.

Overall, the study suggests that applying 270 kg N ha⁻¹ is the most effective in promoting rice straw decomposition, nutrient release, and increasing rice yield in sodic saline rice fields, offering valuable insights for optimizing N fertilizer application and maximizing farmer’s economic benefits.