Effect of organic amendments on soil structure, microbial community and water transport in the Qinghai Lake watershed, North-Eastern Qinghai-Tibet Plateau

The effect of organic amendments on soil structure, microbial community and water transport in alpine ecosystems remains uncertain. Six fertilization regimes from a 2-year field experiment were selected to study this mechanism, i.e. plant litter (PL), organic fertilizer (OF), low concentration of glucose (LCG), medium concentration of glucose (MCG), high concentration of glucose (HCG) and the control (CT). Our results indicated that the soil macroporosity, branch density, length density and node density of soil macropores treated with OF, PL, HCG, MCG and LCG were larger than those of soils treated with CT. The phospholipid fatty acids (PLFAs), bacteria, fungi, actinomycetes, gram-positive bacteria (G+) and gram-negative bacteria (G-) of soils treated with OF, PL, HCG and MCG were larger than those of soils treated with LCG and CT. In contrast, the dyed area ratio and the maximum wetting depth of soils treated with OF, PL, LCG, HCG and MCG were smaller than those treated with CT. There were significant positive correlations between soil organic matter (SOM) and connectivity of soil macropores. Therefore, SOM accumulation significantly improved the soil pore structure, induced the development of the soil microbial community, increased the soil water retention ability and decreased the generation of preferential flow.