摘要:为揭示煤矿复垦区土壤氮素内循环中的矿化及硝化特征，探索不同复垦模式与不同复垦年限下复垦土壤的氮素转化效率，采集山西安太堡露天煤矿中复垦3年、9年、21年苜蓿地及3年荞麦地表层（0~20 cm）土壤，并以3年自然恢复和未复垦新排土为对照，采用间歇淋洗好气培养法与恒温培养法研究各采样地土壤矿化与硝化过程，利用一级反应动力学模型与Logistic方程对有机氮素的矿化与硝化数据进行拟合。结果表明，3年苜蓿地的矿化速率最高，21年苜蓿地的矿化速率最低，且土壤氮素快速矿化主要在培养前7 d，之后逐渐平缓，并在28 d趋于稳定。经一级动力学方程拟合可知，氮矿化势（No）的变化范围为89.28~124.51 mg·kg-1，21年苜蓿地> 3年自然恢复地> 3年苜蓿地> 3年荞麦地>未复垦新排土> 9年苜蓿地；矿化速率常数（k）的变化范围为0.022 6~0.051 9，3年苜蓿地> 9年苜蓿地>未复垦新排土> 3年自然恢复地> 3年荞麦地> 21年苜蓿地。氮矿化势与土壤有机质含量显著正相关（r=0.91）。复垦区各土壤随培养时间的延长硝态氮含量大致为"S"型曲线且可分为3个阶段：前期阶段（0~5 d）-上升阶段（5~14 d）-稳定阶段（14~28 d）；Logistic方程拟合结果显示：复垦年限显著影响硝化高峰出现的时间（不同复垦年限苜蓿地最大相差6.85 d），21年苜蓿地硝化过程剧烈而短促，3年自然恢复地的硝化过程缓慢而漫长；耕地较草地有更大的硝化速率与更长的硝化时间。长期的种植苜蓿复垦显著提高了土壤的氮库容量，矿化过程更为平稳。
关键词:复垦年限/
复垦模式/
氮素转化效率/
有机氮/
矿化/
硝化/
安太堡露天煤矿
Abstract:Soil nitrogen mineralization and nitrification are impacted by microbial activity and soil properties. The reclaimed coal mine soil are artificially reconstructed soil with different properties from farmland soil, such as lower organic matter content, small nitrogen sink, weak microbial activity. In order to reveal the response of nitrogen mineralization and nitrification of reclaimed soils in coal reclamation areas and to explore the soil nitrogen conversion efficiencies under different reclamation patterns and for different reclamation years, a laboratory experiment with soil sampled from the reclaimed coal mine were conducted. There were six sampling soils in Antaibao Opencast Mine, Shanxi Province, which were unreclaimed soil (CK); naturally reclaimed soil for 3 years (NRL); alfalfa pasture soils reclaimed for 3 years (AL3), 9 years (AL9), 21 years (AL21); and buckwheat soil reclaimed for 3 years (BL3). Nitrogen mineralization and nitrification of sampled soils were measured by using Stanford aerobic incubation method and constant temperature culture. And then, the first-order reaction kinetics model and Logistic equation were used to fit the process of organic nitrogen mineralization and nitrification. The results showed that the mineralization rate was highest in alfalfa field reclaimed for 3 years (AL3), and lowest in alfalfa field reclaimed for 21 years (AL21). The mineralization of nitrogen was rapid in the first 7 days and gradually became gentle, tended to be stable in 28 days of incubation. The first-order kinetic equations suggested that nitrogen mineralization potential ranged from 89.28 to 124.51 mg·kg-1 and was in the order of AL21 > NRL > AL3 > BL3 > CK > AL9. The mineralization rate constant ranged from 0.022 6 to 0.051 9, with the order of AL3 > AL9 > CK > NRL > BL3 > AL21. There was a significantly positive correlation between nitrogen mineralization potential and soil organic matter content (r=0.91). The soil nitrogen capacity was significantly increased in the long-term reclamation of grassland, and the mineralization process was more stable. The change of nitrate content in various soils of reclamation area during incubation was roughly following a "S" trend and was divided into three stages, which were the early stage (0-5 d), the rising stage (5-14 d) and the stable stage (14-28 d). Logistic equation fitting results showed that the reclamation years significantly affected the peaking time of nitrification (the max difference was 6.85 days among different reclamation years of alfalfa pasture). The drastic nitrification process in alfalfa pasture reclaimed for 21 years was intense and short, that of naturally restored soil for 3 years was slow and long. The arable land had a greater nitrification rate and longer nitrification time than grassland. In summary, under long term plantation of alfalfa in reclaimed coal mine soil, soil nitrogen sink increased, nitrogen mineralization became stable.
Key words:Reclamation year/
Reclamation mode/
Nitrogen conversion efficiencies/
Organic nitrogen/
Mineralization/
Nitrification/
Antaibao Open-pit Coal Mine
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