Water, Vol. 17, Pages 2244: A Multi-Objective Approach for Improving Ecosystem Services and Mitigating Environmental Externalities in Paddy Fields and Its Emergy Analysis

Water doi: 10.3390/w17152244

Authors:
Naven Ramdat
Hongshuo Zou
Shiwen Sheng
Min Fu
Yingying Huang
Yaonan Cui
Yiru Wang
Rui Ding
Ping Xu
Xuechu Chen

Traditional intensive agricultural system impedes ecological functions, such as nutrient cycling and biodiversity conservation, resulting in excessive nitrogen discharge, CH4 emission, and ecosystem service losses. To enhance critical ecosystem services and mitigate environmental externalities in paddy fields, we developed a multi-objective agricultural system (MIA system), which combines two eco-functional units: paddy wetlands and Beitang (irrigation water collection pond). Pilot study results demonstrated that the MIA system enhanced biodiversity and inhibited pest outbreak, with only a marginal reduction in rice production compared with the control. Additionally, the paddy wetland effectively removed nitrogen, with removal rates of total nitrogen and dissolved inorganic nitrogen ranging from 0.06 to 0.65 g N m−2 d−1 and from 0.02 to 0.22 g N m−2 d−1, respectively. Continuous water flow in the paddy wetland reduced the CH4 emission by 84.4% compared with the static water conditions. Furthermore, a simulation experiment indicated that tide flow was more effective in mitigating CH4 emission, with a 68.3% reduction compared with the drying–wetting cycle treatment. The emergy evaluation demonstrated that the MIA system outperformed the ordinary paddy field when considering both critical ecosystem services and environmental externalities. The MIA system exhibited higher emergy self-sufficiency ratio, emergy yield ratio, and emergy sustainable index, along with a lower environmental load ratio. Additionally, the system required minimal transformation, thus a modest investment. By presenting the case of the MIA system, we provide a theoretical foundation for comprehensive management and assessment of agricultural ecosystems, highlighting its significant potential for widespread application.

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Naven Ramdat www.mdpi.com