Nutrient and Stoichiometric Characteristics of Underground Fissures Soil in Karst Rocky Desertification Regions

Abstract

Aims Underground fissure soil is an important soil resource in karst rocky desertification area, but there are few reports on its physical and chemical properties and soil ecological stoichiometry. This study aims at investigating the physicochemical properties, nutrient content and stoichiometric characteristics of subsurface fissured soils in karst areas, which will help to understand their intrinsic linkage mechanisms and provide a scientific basis for making full use of fissured soils.Methods Typical karst fissures were selected through a combination of field investigation and in-laboratory analysis, and soil physicochemical properties were determined through field sampling and indoor tests. Results We found that as the depth of the fissure soil layer increases, the silt content and clay content increase and the sand content and soil water content continue to decrease. The fissure soil is basically weakly alkaline. The TN content does not change much from the surface to the lower part of the fissure, and the AN, TP and AP contents in the fissure generally decrease. In general, SOC, nitrogen and phosphorus are mainly concentrated in the surface soil compared to the other soil layers in the fissure; the C/N, N/P and C/P ratios are higher in the upper part of the fissure; C/P and N/P are higher and C/ N is lower in SL, while the opposite is true in AL. Conclusions The low nutrient content and high ecological stoichiometry of karst rift soils suggest that rift soils in karst areas need more soil nutrient management, and improvement of quality status.