土壤理化特性对稻田CH_4排放的影响

Methane Emission from Rice Paddy Soils as Influenced by Soil Physico-chemical Properties

为了研究土壤理化特性对稻田CH4 排放的影响 ,室外盆栽试验于 2 0 0 0年水稻生长季在南京农业大学实施 ,1 8个供试水稻土分别取自江苏宜兴、江宁、六合、仪征及宝应等地 .所有供试土壤的季节性CH4 平均排放通量为 6 42± 2 70mg·(m2 ·h) - 1,最低和最高值分别为 1 96mg·(m2 ·h) - 1和 1 1 0 6mg·(m2 ·h) - 1,两者相差约 5 6倍 .单相关分析结果表明 :影响CH4 排放的主要土壤参数为质地、氮素状况及铜含量 .CH4 排放与土壤砂粒含量呈正相关 (r =0 5 2 8,p =0 0 2 4) ,与粘粒含量呈负相关 (r =-0 484,p =0 0 42 ) .氮素含量高的土壤CH4 排放较低 ,CH4 排放与土壤全氮、速效氮和铵态氮含量的线性相关系数分别为 -0 449(p =0 0 62 )、-0 61 1 (p =0 0 0 7)和 -0 649(p =0 0 0 4) .土壤铜含量直接影响CH4 的排放 ,CH4 排放与有效态铜和全铜含量的线性相关系数分别为 -0 5 94(p =0 0 0 9)和 -0 5 47(p =0 0 1 9) .本研究并未观测到CH4 排放与土壤有机碳含量有相关关系 ,这与前人报道的实验室培养测定结果及稻田CH4 排放随土壤有机质含量提高而增加的假设完全不同 .逐步回归分析表明 ,不同土壤间CH4 排放的变异性有 75 5 %可由土壤有效态铜含量、镁 (全量 )

To identify the key soil parameters influencing methane emission from rice paddies, and to quantitatively describe the relationship of methane emission with the soil properties, an outdoor pot experiment with a total of 18 paddy soils sampled from different regions in Jiangsu province was conducted in Nanjing Agricultural University during 2000 rice growing season. Seasonal average rate of CH 4 emission for all the 18 soils was 6 42±2 70mg·(m 2 ·h) -1 , ranging from 1 96 to 11 06mg·(m 2 ·h) -1 , approximately a 5 6\|fold difference between the maximum and the minimum. Correlation analysis indicated that the seasonal average of CH 4 emission was positively dependent on soil sand content ( r =0 528, p =0 024) and negatively on soil clay content ( r =-0 484, p =0 042). Negative correlation of CH 4 emission against soil total nitrogen ( r =-0 449, p =0 062), available nitrogen ( r =-0 611, p =0 007) and NH + 4 N( r =-0 649, p =0 004) was also observed. Copper content of soils has a significant negative impact on CH 4 emission. The correlation coefficient ( r ) of CH 4 emission against soil available copper and with total copper was -0 594 ( p =0 009) and -0 547 ( p =0 019), respectively. No clear relationship existed between CH 4 emission and soil carbon content. A further investigation suggests that the seasonal average rate of CH 4 emission can be quantitatively determined by a linear combination of soil available copper, total manganese, and a ratio of available to total iron ( R 2=0 755, p =0 0001).