福建省耕地土壤全氮密度和储量动态变化

准确估算土壤全氮密度和储量的动态变化能为氮肥优化管理和水体富营养化防控提供重要依据。以位于福建省不同地区的闽侯县、同安区、武平县和永定县1982年11087个样点及2008年1616个样点建立的1∶5万土壤数据库为基础,利用尺度上推的方法分析了1982—2008年福建省耕地全氮密度和储量的动态变化。结果表明,近30年来福建省耕地土壤氮素富集明显,全氮密度和储量分别上升了0.08 kg/m2和1.22 Tg,但不同土壤类型差异较大,紫色土土类、酸性紫色土亚类和猪肝土土属氮素富集最明显,全氮密度均上升了0.18 kg/m2;赤红壤土类、淹育水稻土亚类和赤土土属氮素损失最多,全氮密度均下降了0.10 kg/m2。水稻土土类、渗育水稻土亚类和黄泥田土属全氮储量增加最多,分别达1.24、0.80 Tg和0.71 Tg;赤红壤土类、赤红壤亚类和灰砂泥田土属下降最多,分别达0.13、0.13 Tg和0.08 Tg。因此,在今后的福建省耕地管理中根据不同土壤类型氮素富集程度合理指导施肥,以节约资源和减少氮素流失是十分必要的。

Dynamic change of soil total nitrogen density and storage in cropland of Fujian Province, China

The dynamic change of soil total nitrogen density and storage is very important for optimization of nitrogen fertilizer management and water eutrophication. In this study, four counties, namely Minhou, Tongan, Wuping and Yongding, located in different areas of Fujian Province, China, were selected as typical study areas. Based on the data of field measurements at 11087 sampling sites in 1982 and 1616 sampling sites in 2008, scattered in these four counties, a 1:50000 soil database was carried out of dynamic changes in total nitrogen density and storage in the farmlands of Fujian Province during the 1982-2008 year, using the scaling up method. Results show that nitrogen was enriched obviously, with nitrogen density and nitrogen storage increased by N 0.08 kg/m² and 1.22 Tg in entire Fujian Province, respectively. The degree of N enrichment had a great discrepancy in different soil types. The incresed of nitrogen density in purplish soil, acid purplish soil and liver soil was the highest in soil group, soil subgroup and soil genus, respectively, with total nitrogen density increased by N 0.18, 0.18 and 0.18 kg/m², respectively. By contrast, the decresed of nitrogen density in latosolic red soils, submergenic paddy soils and latosolic soil was the highest in soil group, soil subgroup and soil genus, respectively, with total nitrogen density decreased by N 0.01, 0.01 and 0.01 kg/m², respectively. The incresed of nitrogen storage in paddy soils, percogenic paddy soils and yellow mud field was the highest in soil group, soil subgroup and soil genus, respectively, with total nitrogen storages increased by N 1.24, 0.80 and 0.71 Tg, respectively. By contrast, the decresed of nitrogen storage in latosolic red soils, latosolic red soils and grey sandy mud field was the highest in soil group, soil subgroup and soil genus, respectively, with total nitrogen storages decreased by N 0.13, 0.13 and 0.08 Tg, respectively. Therefore, it is necessary to help famers on scientific fertilization according to the enrichment of various soil type, and to save resources and reduce environmental problems caused by the nitrogen losses.