生物质炭提高石灰性土壤磷有效性的非生物与生物机制

The recycling of P is important for the sustainability of agricultural production and the environmental protection. Biochar was recognized the function of promote soil phosphorus (P) availability. However, it remain largely unknown the mechanism of biochar amendment on soil P recycling. Our previous research found that biochar amendment persistently increased soil P availability, and also increased nutrient cycling related enzyme activity. Therefore, the activation of biochar on soil P was not only physicochemical mechanism, but also the biological active mechanism. This project based on two types of calcareous soils with different P level in north China, and two types of biochar. Laboratory incubation, pot and adsorption kinetics experiment will be conducted in this project. Based on the incubation experiment, we will analysis the relationship between the change of soil phosphorus forms and soil phosphatase activity, microbial community structure and abundance and the functional genes abundance, aimed to reveal the microbial mechanisms of biochar on P availability in calcareous soil. We will conduct an adsorption kinetics experiment with the biochar mix soil after different pot incubation period, and analysis the relation between the change of equation fitting parameters and soil organic matter and soil mineral ion content, which will reveal the physical-chemical regulatory mechanism on soil P availability. Based on the pot experiment, we will investigate the relationship between the change of soil phosphorus forms and microbial community structure and species abundance, the phosphatase activities and functional genes abundance, and the organic acid content in rhizosphere soil, to explore the mechanism of crop root on soil P availability after biochar amendment in calcareous soil. This research will reveal the mechanism of biochar on P availability in calcareous soil and the influence factors, which will provide theory gist to increase P use efficiency and reduce chemical fertilizer use.

生物质炭能够持续增加土壤有效磷的含量，而该过程机理尚不明确。本研究以两种不同磷水平的石灰性土壤和两种类型生物质炭为研究对象，探索生物质炭对石灰性土壤有效磷的生物与非生物调控机制。本研究拟采用培养试验、吸附动（热）力学试验和连续多茬盆栽试验的方法。利用培养试验，分析土壤中磷素形态动态变化与磷酸酶活性、微生物群落结构及丰度、相关功能性基因丰度之间的关系，研究生物质炭对石灰性土壤磷的微生物调控机制。采集不同盆栽时期土壤进行吸附动（热）力学试验，通过土壤磷吸附特性的变化与土壤有机质及矿物离子含量的关系，分析生物质炭对磷素的理化调控机制。利用盆栽试验，分析根际土壤磷形态与微生物群落结构和丰度、及相关功能性基因丰度和土壤各有机酸含量之间的关系，从根系的角度探索生物质炭对磷的活化机制。预期本研究能够揭示生物质炭对石灰性土壤有效磷的生物与非生物调控机制，为农业生产中促进磷素高效减量施用等提供理论基础。

生物质炭施用于农田土壤中能够提高作物生产力，提高养分利用效率，促进农业可持续发展。研究发现，生物质炭能够持续增加土壤有效磷的含量，而该过程机理尚不明确。本项目以不同性质的石灰性土壤和不同类型生物质炭为研究对象，探索生物质炭对石灰性土壤有效磷的生物与非生物调控机制。本研究基于室内模拟试验、田间试验和整合分析等的研究方法。利用培养试验，分析土壤中磷素形态动态变化，土壤胞外酶活性、土壤性状等之间的关系，研究生物质炭对石灰性土壤磷的调控机制。利用盆栽试验，分析根际土壤磷形态与微生物群落结构和丰度等之间的关系，从根系的角度探索生物质炭对磷的活化机制。采集长期田间定位试验的土壤进行吸附动（热）力学试验，研究土壤磷吸附特性的变化与土壤有机质及矿物离子含量的关系，研究土壤磷有效性与土壤胞外酶活性的关系，探讨生物质炭对磷素形态特征的长期调控机制。结果表明：（1）生物质炭施入石灰性土壤中能够持续提高磷有效性，促进稳定态磷的活化，提高胞外酶活性，提高土壤肥力。（2）生物质炭施入潮土中连续种植2茬作物后，仍然能够提高根际土壤养分含量，提高根际胞外酶活性，促进养分循环，改善作物根系构型，提高植株对养分的吸收，促进作物生长。（3）生物质炭施入潮土和褐土两种不同类型的石灰性土壤可长期提高土壤肥力，促进土壤C、N、P元素的周转，增强土壤中稳定态磷的活化，提高磷素有效性，在提高土壤养分的利用效率上长期效应。（4）生物质炭在短期内对土壤养分和作物生长的效应与其活性成分密切相关，其长期效应可能与磷酸酶等的调节作用相关，且在土壤质地、生物质炭类型等因素之间表现出较大的变异性。本研究揭示了生物质炭对石灰性土壤磷有效性持续性影响的生物与非生物调控机制，能够为农业生产中促进磷素高效减量施用等提供理论基础。