Effect of Straw Biochar and Pig Manure Application on the Structure Aggregates in Mountain Red Soil

Purpose The effects of straw biochar amendment of different amounts on the structure of aggregates in mountain red soil were revealed in this study.

Method The different proportions (0, 1% and 1.5%) straw biochar as an additive was selected and added to mountain red soil with pig manure application under organic planting as the original red soil control (CK). And the aggregate structure of treatments was tested.

Result Compared with CK, the contents of water and mechanical stable aggregates greater than 0.25 mm (WSA_0.25 and MSA_0.25) with the increasing amount of straw biochar addition evidently increased by 26.15%, 30.45% and 31.48%, 10.11%, 10.32% and 10.59%, respectively in three treatments, while the mean weight diameters of aggregates (MWD) obviously decreased by 20.41%, 4.08% and 3.06%, respectively. There was no significant difference between CK and couples of biochar and pig manure application, but the percentages of aggregate destruction (PAD) significantly decreased by 18.03%, 22.57% and 22.55%, and the fractal dimensions of water-stable aggregates (D) in soils separately decreased to 2.70, 2.69 and 2.68. Investigations of regression relations between fractal dimensions and contents of aggregates greater than 0.25 mm and correlation relations between soil organic matter and WSA_0.25 clarified that the fractal dimension and soil organic matter were more reasonable choices for showing contents and stability of soil aggregates.

Conclusion It is suggested that there is a significant improvement on contents and stability of soil aggregates under straw biochar with pig manure application.