The mean annual temperature is 16.8 ◦C, with the highest and lowest monthly average temperatures of 28.9 (July) and 4.7 ◦C (January), respectively. Three soils that are widely distributed in the Dongting Lake area were tested: alluvial sandy loamy paddy soil (ASL) from river fluvial wash, purple calcareous clayey paddy soil (PCC) from lake deposits, and reddishyellow loamy paddy soil (RYL) from quaternary red soil.