宁夏不同农业生态区土壤养分时空变化特征

Temporal and spatial variability of soil N, P and K contents in different agroecological regions of Ningxia

根据宁夏耕地土壤监测结果,分析了不同农业生态区土壤氮磷钾养分含量的时空变化特征。结果表明,在1970～2000年的30a里,土壤全氮、全磷和全钾含量没有发生显著变化,而土壤碱解氮和有效磷含量呈较显著或显著增长态势,土壤速效钾含量在山区没有明显增减,而在灌区近15a呈明显下降态势。从两个地区比较来看,土壤氮磷钾养分含量总体上都是灌区高于山区,其中地区间差异最大的是土壤有效磷含量,具有极显著差异的是全氮、碱解氮和有效磷含量,全钾和速效钾含量在地区间存在较显著或显著差异,全磷量在地区间没有显著差异。从地区内变异系数来看,除土壤全钾外,其他都是山区显著大于灌区,山区变异系数的大小依次为全氮>有效磷>速效钾>碱解氮>全磷>全钾,灌区变异系数的大小依次为碱解氮>有效磷>速效钾>全氮>全磷>全钾。不论山区还是灌区,土壤全钾量的变异系数都是最小。

The temporal and spatial variability of soil N, P and K contents in the plough layer(0~20 cm)of farmlands in different agroecological regions of Ningxia was analyzed according to the data of soil nutrients tested from 1970 to 2000. The results showed that the contents of total N, P and K in the soils were relatively steady in the past 30 years. The contents of soil alkali-hydrolyzable N and available P were increased gradually. The content of readily available K was not obviously changed in the semiarid mountain region, but was decreased significantly in the irrigation region along Yellow River during 1985 to 2000. By comparison the contents of soil nutrients in the irrigation region were higher than that in the mountain region as a whole. There was the largest difference between the two regions in available P, and there were very significant differences in total N, alkali-hydrolyzable N and available P contents. There were also significant differences at 10%~5% level in total K and readily available P contents, but no difference in total P content between the two regions. The variation coefficients of all soil nutrients (except total K) in mountain region were obviously higher than that in the irrigation region. The order of variation coefficients in the semiarid mountain region was: total N>available P>readily available K>alkali-hydrolyzable N>total P>total K, and in the irrigation region was: alkali-hydrolyzable N,available P>readily available K>total N>total P>total K. The variation coefficient of total K content was the lowest in both the mountain region and the irrigation region in Ningxia.