近30年江西省耕地土壤全氮含量时空变化特征

SPATIO-TEMPORAL VARIATION OF TOTAL N CONTENT IN FARMLAND SOIL OF JIANGXI PROVINCE IN THE PAST 30 YEARS

以第二次土壤普查和测土配方施肥项目采集的大量土壤样品为基础,以GIS为技术工具,对江西省耕地土壤全氮的时空变化特征进行分析。研究结果表明:1985年和2012年江西省耕地土壤全氮含量在各设区市以及不同土壤类型之间均存在有较大的空间差异。1985年耕地土壤全氮含量最高的为萍乡市,最低的为九江市,空间变异最大为赣州市;2012年耕地土壤全氮含量较1985年整体提高了1个等级,全氮含量最高的为新余市,最低的为九江市,空间变异最大的为九江市。2012年水稻土全氮平均含量较1985年提高了7.24%;无论是在1985年还是2012年,水稻土全氮含量最高的为萍乡市,1985年水稻土全氮含量较低的三个设区市分别为吉安、赣州和九江,2012年则分别为九江、鹰潭和赣州。2012年旱地土壤全氮平均含量较1985年增加了43.88%,其中丰富级水平的土壤面积比例由1985年的7.38%提高至2012年的88.16%。

In order to make soil N management more scientific, N fertilizer application more reasonable and soil N utilization rate of crops higher in Jiangxi Province, spatio-temporal variation of total N in farmland soil of Jiangxi Province from 1985 to 2012 was analyzed by means of the Inverse Distance Weighted interpolation （IDW） method, overlay analysis method and Fisher statistical method in GIS technology based on the large volumes of soil samples collected during the second national soil survey and the project of soil-test-based formulated fertilization. According to the standard of the second national soil survey, total N contents in the farmland soils of Jiangxi have 6 grades, i.e., Grade 1 （〉2.0 g kg^-1） , Grade 2 （ 1.51 to 2 g kg^-1） , Grade 3 （1 to 1.5 g kg^-1） , Grade 4 （0.76 to 1.0 g kg^-1） , Grade 5 （0.51 to 0.75 g kg^-1） and Grade 6 （〈0.5 g kg^-1 ） . Soils in Gradel and Grade 2 are regarded to be high, in Grade 3 and Grade 4, moderate and in Grade 5 and Grade 6, low in total N. Results show that total N contents in farmland soils varied sharply between soils in 11 cities and between soils of different types temporally and spatially in both 1985 and in 2012; and on average the farmland soils of the whole province were all 1 grade higher in 2012 than in 1985. The soils of the high total N level in Jiangxi were mainly distributed in the southern part of Poyang Lake Plain, basins along the Zhe-Gan Railway and Jitai basin in 1985, and more extensively in the whole Poyang Lake plain, basins along the Zhe-Gan Railway, Jitai basin and Ganzhou basin in 2012. In 1985 the soils in Pingxiang were the highest in total N content, in Jiujiang the lowest and in Ganzhou the highest in spatial variability of soil total N content, while in 2012. the soils in Xinyu were the highest in total N content, in Jiujiang the lowest, and in Jiujiang, the highest in spatial variability. Compared with 1985, 2012 was 7.24% higher in total N content in paddy soil and the growth was particularly obvious in soils of the high N level while the areas of the moderate and low levels decreased. The paddy soils the highest in total N content were in Pingxiang in both 1985 and 2012 and the paddy soils the lowest, in Ji＇ an, Ganzhou and Jiujiang, in 1985 and in Yingtan, Ganzhou and Jiujiang in 2012. Total N content in upland soils increased rapidly in 2012 or on average by 43.88% over that in 1985 and the area percentage of upland soils high in total N increased from 7.38% in 1985 to 88.16% in 2012.