Region, especially in the subsoil [29,30], while subsoiling changed the soil structure, allowing increased gas diffusion in the soil. In this study, soils under HT conversion to HTS, RT conversion to RTS and NT conversion to NTS increased CH4 absorption and strengthened the sink capacity of the soils (Fig. 2 A to C); however, these conversions also promoted the emission of N2O (Fig. 2 D to F). This increase may be due to changes in soil conditions as a result of conversion to tillage (Fig. 5). For example, the increase in CH4 absorption after conversion was mainly correlated with soil temperature, soil moisture, soil pH and SOC content according to the correlation analysis (Fig. 3 and Table 2), which is consistent with some previous studies [31?3]. A higher temperature and greater SOC may be advantageous to increasing the amount of CH4 absorbed by the soil (Table 2, Fig. 3A) [34,35]. However, soil moisture and pH were two limiting factors in our study (Table 2, Fig. 3B) that had negative effects on CH4 absorption in the soils [36]. At the same time, subsoiling would reduce subsoil compaction, and some have found improved permeability of soil to increased soil methane sinks [37] and higher bulk density to limit gas diffusion from the soil to the atmosphere, prolonging methane transfer pathways and thereby reducing CH4 and O2 diffusion between the soil and the atmosphere [38]. Sometimes, although increased soil tillage may slightly decrease CH4 uptake [39], this effect is small and can be largely ignored [6,40]. The conditions for the aeration of the soil profile were reduced after irrigation [41,42] that increases emissions of the greenhouse gas N2O through denitrification in farmland [22], the N2O emission peaks also coincided with higher moisture and NH4+-N content in this study (Fig. 2 D to F, Table 2, Fig. 4A), the emissions of N2O were significantly affected by soil moisture and NH4+-N content in each treatment. Some studies have indicated that thereis a significant linear relationship between N2O emissions and soil moisture and nitrogenous fertilizer [21,22]. In addition, there was no significant correlation between N2O emission 23727046 and soil temperature in this study, and similar results were found by Koponen et al. [43]. In contrast, other studies found that at low temperatures, N2O emissions may be hindered by soil N and water content [44,45]. However, in different experimental sites, N2O emission was often related to increased soil temperature [46,47]. These studies demonstrated that when soil moisture and N Licochalcone A web fertilization were not limiting factors to N2O emission, the rate of N2O emission increased as soil temperature increased [22]. 76932-56-4 site Similarly, soil pH also influenced N2O production in soil (Fig. 4B). N2 was mainly produced through denitrification when the soil pH was neutral, and the N2O/N2 ratio increased when soil pH decreased 15755315 [48]. In our study, when soil pH values decreased with irrigation, N2O emissions significantly increased, however, there was no relation to N2O emission in periods of without irrigation, so soil pH does not directly cause soil GHG emissions [36] but via affected the action of microbes [49]. On the other hand, the predominant form of nitrogen is NO3-N or NH4-N after sufficient mixed between soil and straw through tillage, which may produced little N2O in soil, particularly near the soil surface, with an important influence on N2O emissions [12]. Therefore, the CH4 uptake and N2O emissions under HTS, RTS and.Region, especially in the subsoil [29,30], while subsoiling changed the soil structure, allowing increased gas diffusion in the soil. In this study, soils under HT conversion to HTS, RT conversion to RTS and NT conversion to NTS increased CH4 absorption and strengthened the sink capacity of the soils (Fig. 2 A to C); however, these conversions also promoted the emission of N2O (Fig. 2 D to F). This increase may be due to changes in soil conditions as a result of conversion to tillage (Fig. 5). For example, the increase in CH4 absorption after conversion was mainly correlated with soil temperature, soil moisture, soil pH and SOC content according to the correlation analysis (Fig. 3 and Table 2), which is consistent with some previous studies [31?3]. A higher temperature and greater SOC may be advantageous to increasing the amount of CH4 absorbed by the soil (Table 2, Fig. 3A) [34,35]. However, soil moisture and pH were two limiting factors in our study (Table 2, Fig. 3B) that had negative effects on CH4 absorption in the soils [36]. At the same time, subsoiling would reduce subsoil compaction, and some have found improved permeability of soil to increased soil methane sinks [37] and higher bulk density to limit gas diffusion from the soil to the atmosphere, prolonging methane transfer pathways and thereby reducing CH4 and O2 diffusion between the soil and the atmosphere [38]. Sometimes, although increased soil tillage may slightly decrease CH4
uptake [39], this effect is small and can be largely ignored [6,40]. The conditions for the aeration of the soil profile were reduced after irrigation [41,42] that increases emissions of the greenhouse gas N2O through denitrification in farmland [22], the N2O emission peaks also coincided with higher moisture and NH4+-N content in this study (Fig. 2 D to F, Table 2, Fig. 4A), the emissions of N2O were significantly affected by soil moisture and NH4+-N content in each treatment. Some studies have indicated that thereis a significant linear relationship between N2O emissions and soil moisture and nitrogenous fertilizer [21,22]. In addition, there was no significant correlation between N2O emission 23727046 and soil temperature in this study, and similar results were found by Koponen et al. [43]. In contrast, other studies found that at low temperatures, N2O emissions may be hindered by soil N and water content [44,45]. However, in different experimental sites, N2O emission was often related to increased soil temperature [46,47]. These studies demonstrated that when soil moisture and N fertilization were not limiting factors to N2O emission, the rate of N2O emission increased as soil temperature increased [22]. Similarly, soil pH also influenced N2O production in soil (Fig. 4B). N2 was mainly produced through denitrification when the soil pH was neutral, and the N2O/N2 ratio increased when soil pH decreased 15755315 [48]. In our study, when soil pH values decreased with irrigation, N2O emissions significantly increased, however, there was no relation to N2O emission in periods of without irrigation, so soil pH does not directly cause soil GHG emissions [36] but via affected the action of microbes [49]. On the other hand, the predominant form of nitrogen is NO3-N or NH4-N after sufficient mixed between soil and straw through tillage, which may produced little N2O in soil, particularly near the soil surface, with an important influence on N2O emissions [12]. Therefore, the CH4 uptake and N2O emissions under HTS, RTS and.