丹江中游典型小流域土壤总氮的空间分布

Spatial Distribution of Soil Total Nitrogen in a Typical Watershed of the Middle Danjiang River

在丹江鹦鹉沟小流域,利用网格状取样和典型样地取样相结合的方法,进行土样采集,共计采样点268个,测定土壤0～40cm的总氮含量。应用传统统计学和地统计学的方法,对不同深度下土壤总氮含量进行分析。结果表明:土壤总氮含量随土壤深度的增加而降低,不同土层间土壤总氮含量存在显著差异(P<0.01),0～10cm(A1)、10～20cm(A2)和20～40cm(A3)土壤总氮含量平均值分别为0.85、0.47和0.30g/kg。3个土层下,总氮的最优模型均为线性模型,具有中等空间相关性。经Kriging插值分析,不同土层下土壤总氮的空间分布呈带状格局。ANOVA分析表明A1和A2层不同土地利用下土壤总氮含量存在显著差异(P<0.05),不同土层下土壤总氮在不同坡度均存在显著差异(P<0.05)。农地不同土层下土壤总氮含量与海拔、坡度和坡向均呈显著相关性(P<0.01)。研究区0～40cm土壤总氮储量为562.37t,不同土地利用下0～40cm每平方米土壤总氮含量表现为林地>农地>草地,分别为0.343、0.299和0.289kg/m2。

Field sampling was carried out based on a 100 m × 100 m grid system and typical spot samples. A total of 268 sites were sampled in Yingwugou watershed. The samples were collected in three soil layers at a depth of 0-40 cm. Both traditional and geostatistical methods were applied to analyze total nitrogen in the three different soil depths. The results indicated that the total nitrogen content in the soil profile decreased with the increase of soil depth, and there were significant differences among the three soil layers （P 〈 0.01）. The mean total nitrogen contents in 0-10 m （A1）, 10-20 m （A2） and 20-40 cm （A3） were 0.85, 0.47 and 0.30 g/kg, respectively. The best fitted models in the three soil layers were all linear models indicating moderate spatial dependence. The Kriging interpolation showed that the spatial distribution of soil total nitrogen content in different soil layers exhibited ribbon-shaped patterns. The ANOVA showed that the spatial variations of the total nitrogen content for different land use types in A1 and A2 were significant （P 〈 0.05）. The impact of slope on soil total nitrogen content in the three soil depths was significant （P 〈 0.05）. There were significant correlations between the total nitrogen content and elevation, slope and aspect in different soil layers of cropland （P 〈 0.01）. The soil total nitrogen storage in the study are at 0-40 cm was 562.37 t. The total nitrogen contents per square meter at the 0-40 cm soil layer for forestland, cropland and grassland were 0.343, 0.299 and 0.289 kg/m2, respectively.