川中丘陵区涪江流域土壤矿质氮空间分布特征

Spatial Distribution Characteristics of Soil Mineral Nitrogen in Fujiang Watershed in the Hilly Region of the Middle Sichuan,China

采用GPS、地统计及地理信息系统(GIS)相结合的技术和方法研究了川中丘陵区涪江流域土壤矿质氮含量的空间分布特征及其影响因素。结果表明,研究区内土壤硝态氮(NO3--N)和铵态氮(NH4+-N)含量分别为(79.21±24.34)mg·kg-1和(8.89±2.47)mg·kg-1,在不同土壤类型中,土壤硝态氮和铵态氮含量存在极显著差异(P<0.01)。土壤硝态氮含量以许家沟和中河沟区域为中心向北部和南部递增;土壤铵态氮含量以赵家湾、中河沟和任家沟为低值中心(<8.00mg·kg-1)向两旁逐渐增加。从低海拔到高海拔土壤硝态氮含量呈先增加后降低的趋势,土壤铵态氮含量持续降低;在丘体下部和平坝土壤中硝态氮和铵态氮含量均高于其他3种地形土壤中其含量;土壤硝态氮在不同坡度中均值比较为缓坡地>坡地>陡坡地>平地,从平地到陡坡地土壤铵态氮含量呈显著降低趋势;土壤硝态氮含量在小麦与其他作物轮作方式中明显低于油菜与其他作物轮作方式中其含量,土壤铵态氮则相反。

The spatial distribution characteristics and influential factors of soil nitrate nitrogen（NO3^--N） and ammonium nitrogen（NH4^＋-N） in Fujiang River Basin were performed by technology of the Global Position System,geostatistics and Geographic Information System（GIS）. The results indicated that the contents of soil NO3^--N and NH4^＋-N were（79.21±24.34） mg·kg^-1 and（8.89±2.47） mg·kg^-1,respectively. Meanwhile,the contents of soil NO3^--N and NH4^＋-N took on highly significant difference in different soil types（P0.01）. The lowest value regions（68.00 mg·kg^-1） of soil NO3^--N contents were mainly distributed in Xujiagou and Zhonghegou,and increased gradually towards south and north part. Taking the Zhaojiawan,Zhonghe Valley and Renjia Valley as the low center,the contents of soil NH4^＋-N increased to the both sides. From low elevation to high elevation,the contents of soil NO3^--N were increased firstly then declined and the contents of soil NH4^＋-N were steady decreased. The contents of soil NO3^--N and NH4^＋-N in the bottom of hilly and in the flatland were higher than in other three landforms. The contents of soil NO3^--N were highest in gentle slope land,then in slope land and in steep land,and were lowest in the flat land. However,the contents of soil NH4^＋-N were significantly increased from flat land to steep land. The soil NO3^--N contents in the cropping system of wheat-other crop were lower than in the cropping system of rape-other crop,and the soil NH4^＋-N contents were reverse.