Spatial variability analysis of soil quality parameters in a watershed of Sub-Himalayan Landscape - A case study

摘要

Soil organic carbon (SOC) is a key component in maintaining soil quality. Mapping thelocal scale variations in the distribution and stratification of SOC and other soil qualityparameters across different layers has always been a challenging task, in the currentglobal scenario of changing climates. The study was aimed to investigate the spatialdistribution of SOC and other soil quality parameters including SOC stratification ratio andCN ratio in a small hilly watershed (? 10 km2) located in the mid Himalayan region ofHimachal Pradesh, India. Soil samples were collected in November 2015, from 75 points attwo depths (0-15 cm and 15-30cm), along with their geographical coordinates using aGlobal Positioning System (GPS). The results revealed that SOC concentration (g kg-1)decreased with increasing soil depth, throughout the study area and differed significantly(P0.01) between the two depths in vertical soil profile. The SOC stratification ratio valueswere greater than 1.2 in major portion of watershed indicating a spatial improvement insoil quality. C: N ratio, another important soil quality attribute values were found to be12:1, indicating high degree of soil quality and increased rate of organic mattermineralization. The spatial distribution maps of SOC content (g kg-1), SOC stratificationratio as well as CN ratio of study area were generated using Inverse Distance Weighted(IDW) interpolation approach. Additionally soil quality index (SQI) was also computedusing various soil quality parameters based on Analytical Hierarchy Process (AHP) andtheir spatial distribution was analyzed in the watershed. Nearly 76% of the study area hadSQI values in the range of 60-75, whereas 22.16% of the area had SQI60 and 2.59% hadSQI75. The overall results indicated that a higher degree of soil quality existed at thehigher elevation regions of the watershed. Majority of the soils in the watershedaccounted for only 60% of the maximum possible value of SQI, which necessitates theadoption of better management practices for improving the soil quality.