Effects of checkerboard barriers on the distribution of aeolian sandy soil particles and soil organic carbon

Abstract

Sand-barrier setup is an important measure to protect the topsoil against wind erosion. Salix psammophila checkerboard barriers are used widely in the Mu Us Sandy Land in order to ensure the safety of life and agricultural production. To measure variations in soil structure and quality caused by barriers with different duration (7 years and 2 years), the composition of aeolian sandy soil particles and the soil organic carbon (SOC) distributions are studied; the dunes with no barrier are used as controls (CK). Analyzed by multi-fractal parameters, the topsoil samples are collected in the field and tested in the laboratory.The predominant soil particles are fine sand, medium coarse sand and clay, and the contents of silt and very fine sand increase with extending barrier duration, which shows a wider distribution range, greater dispersion degree and larger soil particle heterogeneity. The aeolian sandy particles, particularly fine granular grains, are deposited and accumulate at the bottom and top of dunes because of the barrier blocking effect.The particle size distribution (PSD) heterogeneity is the highest in 7-year barrier dunes and the lowest in the no barrier dunes. The mean values of D0 (Capacity dimension) of 7-year barrier dunes, D1 (entropy dimension) of the no barrier dunes and D1/D0 of 2-year barrier dunes are maxima. In addition, the PSD range and distribution increased with prolonged dune barrier duration, as well as the changes of Δf(∂) (shape of the multi-fractal spectrum) and Δ∂ (width of multi-fractal spectrum).SOC content increased with increasing barrier duration and decreasing D1/D0. The average SOC contents of 7-year barrier dunes were the maximum and one of no barrier dunes had the minimum SOC content, and their difference was significant (P < 0.05). In both the PSD and SOC distribution, the 7-year barrier showed better results on the topsoil than that of 2-year and no barrier situation.Correlations between the SOC content and the PSD multi-fractal parameters of both 7-year and 2-year barrier dunes are significantly different (P < 0.01). The multi-fractal parameters can be used to indicate soil nutrient contents, which provide fundamental knowledge for evaluating the effectiveness of ecological engineering to restore soil quality and structure to sandy ecosystems. Salix psammophila checkerboard sand barriers play a role in increasing the fine particles and soil organic carbon in surface dune soil, which is helpful in restoring the Mu Us sand ecosystem. The early use of sand barriers is therefore recommended.