基于Nemerow法的核桃林土壤肥力分析与评价

Soil Fertility Analysis and Evaluation of Walnut Grove Based on Nemerow Method

研究云南核桃和新疆核桃林土壤肥力状况,探索核桃林土壤肥力的主要影响因子,为核桃林地平衡施肥提供参考依据。以维西县核桃林为对象,采集核桃林地深0~20、20~40、40~60 cm 3个土层90个样点的土壤,测定pH、有机质、碱解N、有效P、速效K等因子,运用Nemerow法和第2次土壤普查分级标准进行土壤肥力综合评价。结果表明:1)土壤养分因子变异系数在10.0%~133.3%,速效K属于强变异;pH总体均值为6.51,呈弱酸性,随着土层深度的增加,pH呈上升趋势;有机质和碱解N总体均值分别为25.2 mg·kg^-1和78.8 mg·kg^-1,均分布在Ⅲ、Ⅳ级,有机质属中上水平,碱解N属中等水平,二者均表现为明显的表聚现象和随土层深度的增加含量下降的相似性;有效P总体均值为9.66 mg·kg^-1,分布在Ⅲ、Ⅳ级,属中等水平;速效K总体均值为69.4 mg·kg^-1,分布在Ⅳ、Ⅴ、Ⅵ级,属低水平。2)核桃林土壤的有机质、碱解N、有效P、速效K 4个养分因子均表现为0~20 cm土层含量最高,随着土层深度的增加,含量总体均呈下降趋势,差异显著性分析表明各采样点和各土层之间4个养分因子均表现为差异显著。3)Nemerow法评价结果显示,该研究区域内核桃林土壤综合肥力指数均值为1.37,肥力指数最高1.54,最低1.12,属于中等水平,速效K是研究区域内核桃林地的主要限制因子。

The purpose of this study was to investigate the soil fertility of walnut grove to offer reference for the balanced fertilization in walnut cultivation.The experiment was conducted in Weixi County of Yunnan Province.Soil samples were collected from three soil layers(0-20,20-40,and 40-60 cm)in 90 plots,of which relative parameters were measured,such as pH,organic matter(OM),alkali-hydrolyzed nitrogen(Navl-alk),available phosphorus(Pavl),and available potassium(Kavl).Based on Nemerow method and grading standard of the Second National General Soil Survey,the soil fertility was assessed comprehensively.The results showed that 1)the variation coefficients of soil nutrients were between 10.01%and 133.29%,in which the Kavl varied most significantly.The average soil pH was 6.51,which was in the range of weak acidity.It increased with soil depth.The average of soil OM and Navl-alk were 25.2 and 78.8 mg·kg^-1,respectively,which ranged between classⅢandⅣ.The fertility of OM was in the level of above the average,and the Navl-alk was in average level.Both soil OM and Navl-alk presented surface aggregation phenomena,and decreased with soil depth.The average of soil Pavl was 9.66 g·kg^-1,ranged in classⅢandⅣ,belonging to middle level.The average of Kavl was 69.4 mg·kg^-1,it ranked in classⅣ,ⅤandⅥ,belonging to middle and low levels.2)All the soil nutrients(OM,Navl,Pavl,and Kavl)were highest in 0-20 cm soil layer,and decreased with soil depth.Significant differences in the contents of soil nutrients were observed among different sample sites and soil layers.3)The evaluation results based on Nemerow method indicated that the average of fertility index was 1.37(1.54 in maximum and 1.12 in minimum),the soil fertility was in medium level.Kavl was the main limiting factor in the research area.