Abstract:
Objective Field experiment was used to explore the improvement effect of different biochar application amounts on tropical farmland to improve soil quality from the perspective of soil aggregates.
Methods Peanut shell biochar was used in the experiment, and the application amounts were 10 t hm−2 (P10), 20 t hm−2 (P20), 40 t hm−2 (P40) and 60 t hm−2 (P60), with no biochar (CK) as the control. One year after biochar application, soil aggregates and soil organic carbon and total nitrogen contents were measured in 0-10 cm, 10-20 cm and 20-30 cm soils.
Results Biochar application significantly increased the aggregate content of 2-1 mm in 10-20 cm soil layer and < 0.25 mm in 20-30 cm soil layer, and significantly increased the aggregate stability in 10-20 cm soil layer. Biochar application increased the contents of organic carbon and total nitrogen in raw soil and aggregates with different particle sizes, and the effectiveness were most obvious in P40 and P60 treatments. Biochar application increased the contribution rates of organic carbon and total nitrogen in the soil layer of 10-20 cm and 2-1 mm grain size aggregates. P60 treatment increased the C/N of aggregates and primary soil in 0-10 cm and 10-20 cm soil layers. The amount of biochar application, soil depth and their interactions had significant effects on soil aggregate stability, aggregate composition, and aggregate organic carbon and total nitrogen contents.
Conclusion In this experimental design, the application of 20 t hm−2 and 60 t hm−2 biochar could significantly improve the stability of soil aggregates, and the application rates of 40 t hm−2 and 60 t hm−2 biochar had the most obvious effect on the improvement of soil aggregate organic carbon and total nitrogen contents. In this study, the application of biochar above 40 t hm−2 can effectively improve tropical farmland soil and improve soil quality.
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