摘要：Assessment of the nitrogen （N） balance and its long-term trend is necessary for management practices because of the negative environmental effects caused by an imbalance of reactive N in grassland ecosystems. In this study, we designed a module for the IAP-N （Improving Anthropogenic Practices of managing reactive Nitrogen） model to enable it to assess the N budget of regional grasslands. The module was developed to quantify the individual components of the N inputs and outputs for grassland ecosystems using livestock and human populations, grassland area, and fossil-energy consumption data as the model inputs. In this paper, the estimation approaches for individual components of N budget, data acquisition, and parameter selection are described in detail. The model was applied to assess the N budget of Inner Mongolia in 2006 at the county scale. The simulation results show that the most important pathway of N outputs from the grassland was livestock intake. The N output from livestock intake was especially large in the middle of Inner Mongolia. Biological fixation, atmospheric deposition, and livestock excreta deposition were comparably important for the N inputs into the grassland. The N budget for Inner Mongolia grassland in 2006 was -1.7×10 8 ±0.6×10 8 kg. The case study for Inner Mongolia shows that the new grassland module for the IAP-N model can capture the characteristics of the N budget in a semiarid grassland.

摘要：设计了一套适合于FACE(free airCO2 enrichment)平台的旱地土壤气体CO2 浓度廓线测定方法 ,并将其应用于田间实验 .在江苏省无锡市郊区具有太湖地区典型水稻土的稻麦轮作农田 ,对FACE和对照麦田以及裸土 0～ 30cm土层的土壤气体CO2 浓度廓线进行了观测研究 .结果表明 ,所采用的方法满足进行旱地农田土壤气体CO2 浓度廓线研究的要求 ;在 0～ 30cm土层中 ,上层土壤气体中的CO2 向上垂直扩散要比下层土壤快 ;在作物旺盛生长期 ,大气CO2 浓度升高 2 0 0± 4 0 μmol·mol-1使 0～ 30cm土层的土壤气体CO2 浓度显著提高 14 %± 5 % (t 检验P <0 .0 0 1) .