山核桃林地土壤肥力状况及其空间分布特征

为探明山核桃Carya cathayensis产地土壤肥力质量状况和空间分布特征，指导林农合理施肥，选取杭州市临安区山核桃产区为研究区域，以土壤pH值、有机质、碱解氮、有效磷、速效钾为研究对象，开展了该区土壤养分状况等级评价，并采用地统计学等空间分析方法对土壤养分空间分布特征进行研究。结果表明:研究区土壤pH值平均为pH 5.23，87%土壤pH值为pH 4~6，研究区土壤酸化严重。土壤有机质平均为31.6 g·kg-1，土壤碱解氮、有效磷、速效钾平均分别为155.40，14.04，85.73 mg·kg-1。根据《浙江土壤》肥力等级划分标准（1级土壤成分质量分数低，4级土壤成分质量分数高）可知:土壤有机质质量分数主要处于第3等级和第4等级，比例为54%。土壤碱解氮质量分数处在分级标准的第3等级且所占比例为76%。土壤速效钾大于50 mg·kg-1的区域占80%。相反，土壤有效磷不足，63%的土壤有效磷不足10 mg·kg-1，处在第1等级和第2等级标准，难以满足山核桃生长。土壤各养分变异系数为27.15%~141.03%，表明研究区林地土壤养分具有不同程度的变异性。空间分析结果显示:研究区土壤pH值和养分均具有明显的空间分布格局。山核桃产量高低不一，与土壤养分具有一定的空间对应关系。山核桃林地土壤严重酸化，土壤有机质、碱解氮和速效钾都比较充足，而大部分地区有效磷不足。

Soil fertility and its spatial distribution for Carya cathayensis stands in Lin'an,Zhejiang Province

To identify soil fertility quality and its spatial distribution differences in Carya cathayensis stands and to guide farmers with fertilizer application, the main plantation area in Lin'an was selected for this study. In this study, differential GPS was used to locate and navigate in the field and a soil sample was collected within a radius of 10 m and a total of 189 soil samples were collected from 7 townships in Lin'an. Soil pH and status of nutrients (organic matter, available N, available P, and available K) were evaluated and their spatial distribution characteristics were revealed by geostatistics and Kriging interpolation. Results indicated that the average soil pH was 5.23 with 87% of the soil pH values in the range of 4-6 meaning soil was seriously acidic. The average organic matter content in the soil was 31.6 g·kg-1 with average available N of 155.40 mg·kg-1, available P of 14.04 mg·kg-1, and available K of 85.73 mg·kg-1. Soil organic matter, available N, and available K were abundant. According to the standard fertility grading for Zhejiang Soil (with first representing low content and fourth representing high content), soil organic matter was mainly in the third or fourth grades accounting for 54% of the soils and soil available N was in the third grade for 76% of the soils. Soil available K was more than 50 mg·kg-1 for 80% of the soils. Soil available P, however, was insufficient for 63% of the soils at less than 10 mg·kg-1 which meant the first or second grades. Coefficients of variation for soil nutrients were between 27.15% and 141.03% indicating that soil nutrients in the study area had different degrees of variability. Yield of C. cathayensis varied from town to town and had a spatial correspondence to soil nutrients. This study showed that stands were seriously acidic with soil organic matter, available N, and available K sufficient, but in most areas available P was insufficient to meet the growing needs of C. cathayensis.