## 2 Materials and Methods
### Negative reconciliation value  
In addition to the above ES, a PFE also has negative ES, such as greenhouse gas (GHG) emissions, water consumption, soil and water pollution caused by excessive use of agricultural chemicals and fertilizers, etc. Therefore, it is necessary to evaluate these negative values and reduce these negative impacts. 1. Greenhouse gas emission Since paddy fields are permanently under irrigation, which provides an anaerobic environment for the soil, the interaction of organic fertilizers, humus, and rice root secretions and decomposition in the soil lead to GHG emissions, such as CH\({}_{4}\) and N\({}_{2}\)O [39]. The global warming potential (GWP) recommended by IPCC [54] was used to convert CH\({}_{4}\) and N\({}_{2}\)O emissions into CO\({}_{2}\) emissions [64], and the carbon tax method was used to estimate the negative regulation value of greenhouse gas emissions in PFE: \[ES_{9}=\left(E_{CH_{4}}\times GWP_{CH_{4}}+E_{N_{2}O}\times GWP_{N_{2}O}\times T _{N}+T_{N}\times E_{N}+T_{P}\times E_{P}+T_{K}\times E_{K}\right)\times P_{C}\] where, \(ES_{9}\) is the negative ESV caused by greenhouse gas emissions (RMB 10 k); \(GWP_{CH4}\) and \(GWP_{N2O}\) are GWP for CH\({}_{4}\) and N\({}_{2}\)O in the past 100-year time horizon, 28 and 265, respectively, according to the IPCC [54]; \(E_{CH4}\) is the CH\({}_{4}\) emission factor per unit area of paddy field (kg/ha), and the value of 0.84 was adopted in this study [65]. \(E_{N2O}\) (kg/ha) is the N\({}_{2}\)O emission generated per unit nitrogen application rate in a paddy field, and the value of 0.256 was adopted in this study [65]; The values of \(T_{N}\), \(T_{P}\) and \(T_{K}\) are the amount (kg/ha) of N, P and K fertilizers used per unit area of paddy field, which are 120, 128 and 112, respectively. \(E_{N}\), \(E_{P}\) and \(E_{K}\) represent the greenhouse gases (kg CE/kg) emitted during the production of N, P and K fertilizers, respectively, with values of 2.12 \(\times\) 10\({}^{-3}\), 6.4 \(\times\) 10\({}^{-4}\) and 1.8 \(\times\) 10\({}^{-4}\) in this study; \(P_{c}\) is the Swedish carbon tax rate [55] of USD 150/t carbon, equivalent to RMB 996.34/t, as in Equation (7). 2. Water consumption The water resource consumption of a PFE is mainly transpiration, evaporation and underground leakage. Underground leakage can supplement groundwater in rice planting areas, which does not belong to the direct consumption of rice growth and should be a positive ESV. Therefore, we estimated only the value of rice growth water consumption. The market value estimation method is as follows: \[ES_{10}=A\times V_{r}\times P_{w},\] (19) where, \(ES_{10}\) is the negative ESV (RMB 10 k) caused by water consumption; \(V_{r}\) is the water demand per unit area of paddy field, that is the evapotranspiration ET (mm) during the growth period of rice; \(P_{w}\) is the agricultural water price (RMB/m\({}^{3}\)) and the value taken in this study was 0.24 [57]. 3. Agrochemical pollution A large amount of chemical fertilizers, herbicides and pesticides are used during the growth of rice, which are highly polluting the paddy fields, surrounding waters and soil. The environmental cost method was used to estimate them according to: \[ES_{11}=M_{f}\times C,\] (20) where, \(ES_{11}\) is the negative ESV caused by the pollution of agrochemicals (RMB 10 k); \(M_{f}\) is rice yield (t); \(C\) is the cost of environmental pollution control caused by excessive use of agrochemicals, here assumed to be 0.11 (RMB/kg) [66]. * NESV The NESV of the PFE is the difference between the positive ESV and the negative ESV.