Abstract
Food demand and soil sustainability have become urgent concerns because of the impacts of global climate change. In subtropical and tropical regions, practical management that stabilizes and prevents organic fertilizers from rapid decomposition in soils is necessary. This study conducted a short-term (70 days) incubation experiment to assess the effects of biochar application on the decomposition of added bagasse compost in three rural soils with different pH values and textures. Two rice hull biochars, produced through slow pyrolization at 400 °C (RHB-400) and 700 °C (RHB-700), with application rates of 1%, 2%, and 4% (w/w), were separately incorporated into soils with and without compost (1% (w/w) application rate). Experimental results indicated that C mineralization rapidly increased at the beginning in all treatments, particularly in those involving 2% and 4% biochar. The biochar addition increased C mineralization by 7.9%–48% in the compost-amended soils after 70 days incubation while the fractions of mineralized C to applied C significantly decreased. Moreover, the estimated maximum of C mineralization amount in soils treated with both compost and biochar were obviously lower than expectation calculated by a double exponential model (two pool model). Based on the micromorphological observation, added compost was wrapped in the soil aggregates formed after biochar application and then may be protected from decomposing by microbes. Co-application of compost with biochar may be more efficient to stabilize and sequester C than individual application into the studied soils, especially for the biochar produced at high pyrolization temperature.
Highlights
Climate change and food demand are currently the two most crucial concerns for agricultural scientists throughout the world
The cation exchange capacity (CEC) were consistent with the contents of clay and organic carbon in these soils
The total carbon (TC) of the compost and biochars was in the range of 30%–33%, and the compost contented more total nitrogen content (TN) than the biochars did
Summary
Climate change and food demand are currently the two most crucial concerns for agricultural scientists throughout the world. How to maintain the soil organic matter (SOM) levels in soils is a key consideration in agricultural productivity and carbon sequestration, in agricultural lands in subtropical and tropical regions. Mekuria et al (2014) [1] mentioned that mulches, compost, or manure can be effective in enhancing soil organic carbon pool and agricultural productivity in the tropic regions, but these amendments were often short-lived. The added organic matters were usually mineralized to CO2 rapidly leading to large-scale leakage in subtropical/tropical regions. Developing strategies for reducing the mineralization of added OM and increasing carbon sequestration in subtropical/tropical rural soils is necessary to facilitate land sustainability [2,3]. Applying biochar to agricultural soils is considered to improve soil quality effectively [5,6,7,8] while sequestering carbon and reducing greenhouse gas emission from soils [7,8]
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