A Comprehensive Benefit Evaluation of the Model of Salt-Tolerant Crops Irrigated by Mariculture Wastewater Based on a Field Plot Experiment

The intensified development of aquaculture and excessive use of agricultural fertilizers pose a threat to natural resource availability and deteriorate the environment. Utilizing aquaculture wastewater from mariculture for agricultural irrigation can mitigate pollution and alleviate the pressure on natural resources. This study investigated the comprehensive benefits of using freshwater and mariculture wastewater for irrigation, employing two concentration levels of mariculture wastewater in a pot experiment with saline-tolerant rice. Furthermore, we quantitively assessed the integrated benefits for farmland by utilizing an ecosystem service function value assessment and emergy value theory. The results indicate a significant enhancement in the growth and yield of saline-tolerant rice when irrigated with mariculture wastewater. Specifically, the theoretical yield increased by 9.01% relative to freshwater irrigation. Irrigation using aquaculture wastewater significantly enhanced the nutrient concentrations in the soil, including soil organic carbon (SOC), avail-K (AK), Olsen-P (OP), and alkali-N (AN). Additionally, the uptake of these nutrients by salt-tolerant crops during their late reproductive stage effectively mitigated the rise in soil salinity induced by the wastewater irrigation practice. Under experimental conditions, wastewater irrigation conferred superior ecological benefits compared with freshwater irrigation. The comprehensive benefits of wastewater irrigation, valued at 104,439.10 RMB/hm², exceeded those of freshwater irrigation by 188.8%. The utilization of mariculture wastewater effectively enhances the coastal environment, augments crop yields, and diminishes treatment costs. From the perspectives of revenue enhancement, environmental compatibility, and sustainability, the model of utilizing salt-tolerant crops irrigated with mariculture wastewater holds substantial promotional and practical significance.