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Dynamics of N 2O concentration, diffusion flux and net turnover rate in soil profile of t ypical vegetable field*(PDF)

Chinese Journal of Applied & Environmental Biology[ISSN:1006-687X/CN:51-1482/Q]

2019 05
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Dynamics of N 2O concentration, diffusion flux and net turnover rate in soil profile of t ypical vegetable field*
MA Zhi-yong1 JIA Jun-xiang1** XIONG Zheng-qin2 XU Jian-min1 WANG Ling1 & ZHANG Jing1
1 College of Resources and Environment, National Experimental Teaching Demonstration Center for Agricultural and Environmental, Shanxi Agricultural University, Taigu 030801, China
2 Jiangsu Key Laboratory of Low Carbon Agriculture and GHGs Mitigation / College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
vegetable plot soil profile Nitrous oxide diffusive flux net turnover rate

The concentrations of nitrous oxide (N2O) at 7, 15, 30 and 50 cm soil depths under bare fallow, rotation vegetable field (rotation of Garland chrysanthemun-Tung choy-Bok choy) were monitored using a special in situ soil gas collection device and gas chromatography to explore the production site , diffusion flux and net turnover rate of N2O in soil profiles. The results showed that the concentration profile of N2O present dramatically spatial and temporal?variability. Average N2O concentration at depth of 7 cm, 15 cm, 30 cm and 50 cm from rotation vegetable field were 1.9, 8.7, 9.2 and 26.7 times of corresponding soil layer from bare fallow field, respectively. Average N2O concentration increased with the soil depth within the range of 0-30 cm soil layer, then decreased at the depth of 30- 50 cm. These indicated that large nitrogen fertilizer application promoted N2O production at the top soil layers. The diffusion fluxes ranged from -354 to 420 μg N m -2h-1 in bare fallow and 482 to 1 510 μg N m -2h-1 in rotation field, respectively. It was concluded that N2O was mainly absorbed by soil at depth of 30-50 cm layer according to negative N2O diffusion fluxes value at same soil layer. The diffusion fluxes at depth of 7- 15 cm layer in rotation field, as high as 1 510 μg N m -2h-1, were higher 68.1%, 2.5% and 36.6% than those at depth of 0-7 cm, 15-30 cm and 30-50 cm soil layer, respectively. Therefore, the key site of N2O production was at depth of 7-30 cm soli profile.Net N2O turnover rates from bare fallow and rotation vegetable were negative at depth of 0-15 cm soil layer, but positive of 15-50 cm. It was concluded that the fastest N2O turnover occurred in the middle layer of soil profile (7-30 cm). In conclusion, the distribution of N2O concentration first increased and then decreased with the?increase?of?N2O concentration. N2O mainly produced at the depth of 30 cm soil, meanwhile diffused to ambient. These results could be used as references for understanding N2O production sites and transformation process in vegetable field ecosystem.




Last Update: 2019-03-15