Chen Shu-Tao, Huang Yao
College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
J Environ Sci (China). 2006;18(5):937-43. doi: 10.1016/s1001-0742(06)60018-1.
A facility of BaPS (Barometric Process Separation) was used to determine soil respiration, gross nitrification and denitrification in a winter wheat field with depths of 0-7, 7-14 and 14-21 cm. N2O production was determined by a gas chromatograph. Crop root mass and relevant soil parameters were measured. Results showed that soil respiration and gross nitrification decreased with the increase of soil depth, while denitrification did not change significantly. In comparison with no-plowing plot, soil respiration increased significantly in plowing plot, especially in the surface soil of 0-7 cm, while gross nitrification and denitrification rates were not affected by plowing. Cropping practice in previous season was found to affect soil gross nitrification in the following wheat-growing season. Higher gross nitrification rate occurred in the filed plot with preceding crop of rice compared with that of maize for all the three depths of 0-7, 7-14 and 14-21 cm. A further investigation indicated that the nitrification for all the cases accounted for about 76% of the total nitrogen transformation processes of nitrification and denitrification and the N2O production correlated with nitrification significantly, suggesting that nitrification is a key process of soil N2O production in the wheat field. In addition, the variations of soil respiration and gross nitrification were exponentially dependent on root mass (P<0.001).
利用气压过程分离（BaPS）设备测定了冬小麦田0 - 7厘米、7 - 14厘米和14 - 21厘米深度处的土壤呼吸、总硝化作用和反硝化作用。通过气相色谱仪测定N2O的产生量。测量了作物根系生物量和相关土壤参数。结果表明，土壤呼吸和总硝化作用随土壤深度增加而降低，而反硝化作用变化不显著。与免耕地块相比，翻耕地块的土壤呼吸显著增加，尤其是在0 - 7厘米的表层土壤中，而总硝化作用和反硝化作用速率不受翻耕影响。发现前一季的种植方式会影响下一季小麦生长季节的土壤总硝化作用。在0 - 7厘米、7 - 14厘米和14 - 21厘米这三个深度处，与前作玉米的地块相比，前作水稻的地块总硝化作用速率更高。进一步研究表明，所有情况下硝化作用约占硝化和反硝化总氮转化过程的76%，且N2O产生与硝化作用显著相关，这表明硝化作用是麦田土壤N2O产生的关键过程。此外，土壤呼吸和总硝化作用的变化与根系生物量呈指数关系（P<0.001）。
