FIGURE 1 Experimental set-up for soil temperature monitoring and soil gas sampling in a lysimeter
FIGURE 2 Variations of root biomass (A), mean root diameter (B), and root length density (C) with groundwater depth at 75% (75% NF), 100% (100% NF), and 125% (125% NF) of normal fertilizer application rate
FIGURE 3 Variations of shoot biomass (A) and root-shoot biomass ratio (B) at 75% (75% NF), 100% (100% NF), and 125% (125% NF) of normal fertilizer application rate
FIGURE 4 Relationships between soil CO2concentration soil water content with (A), organic matter content (B), and total N concentration (C) averaged in the soil depth of 0–20 cm during growing season for all tested groundwater levels and fertilization levels. *** indicate statistical significance at the 0.001 probability level
FIGURE 5 Relationships between soil CH4concentration soil water content with (A), organic matter content (B), total N (C) and available K (D) concentrations averaged in the soil depth of 0–20 cm during growing season for all tested groundwater levels and fertilization levels. *, ** and *** indicate statistical significance respectively at the 0.05, 0.01 and 0.001 probability levels
FIGURE 6 Relationship between the averaged soil CO2 concentration in the depth of 0–40 cm and root biomass for all tested groundwater depths and fertilization levels. *** indicate statistical significance at the 0.001 probability level
FIGURE 7 Relationships between soil CO2concentration with activities of urease (A), phophatase (B), and sucrase (C) averaged in the soil depth of 0–20 cm during growing season for all tested groundwater levels and fertilization levels. ** and *** indicate statistical significance respectively at the 0.01 and 0.001 probability levels