Ecosystem services and cost-effective benefits from the reclamation of saline sodic land under different paddy field systems

Reclamation of saline-sodic soils can unlock vast potential resources, relieve food shortages, and increase valuable ecosystem services. While previous investigations have focused on the current ecosystem service (ES) value of reclaimed paddy fields, the potential long-term costs and benefits of reclamation are still largely unknown. To fill this important research gap, we assessed ES values of reclaimed paddies at the field scale, using primary data collected from 15 different paddy management systems. We assessed the market and non-market benefits, costs, and benefit-cost ratios (BCR) of three different reclamation models and two coculture models across a chronosequence of paddy sites (cultivated for up to 50 years). Our results demonstrate that the addition of cellulose sulfonated modified composite (CSMC) and flue gas desulfurization gypsum (FGDG) substantially increased the net ecosystem service value (NESV) by 16.53 % and 52.21 %, respectively, compared to control paddy cultivation sites. Additionally, integrated rice-crab and rice-fish coculture systems presented great increases in market value (48.48 % and 51.39 %, respectively) compared with that of monoculture systems. Ecosystem provisioning and gas regulating services increased alongside market benefits over longer cultivation periods, indicating potential advantages of long-term paddy cultivation. After 50 years of operation, the cumulative benefit of the CSMC system was approximately 455058.88 ¥ ha⁻¹, which was approximately 1.6 times greater than the control. These results indicate that additional investment in the CSMC system can produce a high margin benefit-cost ratio (MBCR). Given appropriate management models and policies, CSMC inputs and rice-fish co-culture represent the best-performing reclamation system in this study. Our study lays the foundation for associated studies on related government policy, corporate investments, and agricultural production.