Key Laboratory of Watershed Non-point Source Pollution Control and Water Eco-security of Ministry of Water Resources, College of Environmental and Resources Sciences, Zhejiang University, Hangzhou 310058, China.
Key Laboratory of Watershed Non-point Source Pollution Control and Water Eco-security of Ministry of Water Resources, College of Environmental and Resources Sciences, Zhejiang University, Hangzhou 310058, China; Department of Water Relations & Field Irrigation, National Research Centre, Dokki, Giza, Egypt.
J Environ Manage. 2023 Jan 15;326(Pt A):116745. doi: 10.1016/j.jenvman.2022.116745. Epub 2022 Nov 12.
Colloidal phosphorus (P) in paddy soils can pose a serious threat to the water environment. Biochar amendment not only directly absorb P to reduce the runoff loss, but also create hotspots for microbial communities which simultaneously affects soil P. However, despite the crucial role of microorganisms, it remains elusive regarding how biochar and its feedstock types affect the relationships of soil microbial communities and P in soil matrix (such as at soil aggregate level). To address the knowledge gap, we explored the (in)direct effects of biochar on the soil P in physically separated fractions including micro- (53-250 μm) and macroaggregates (250-2000 μm). Results showed that straw and manure biochars decreased the soil P content by 55.2-56.7% in microaggregates and 41.2-48.4% in macroaggregates after 120 days of incubation, compared to the respective control. The fungal communities showed a significantly correlation (0.34, p < 0.05) with P content in the macroaggregates, whereas the bacterial communities were extremely significantly correlated (0.66, p < 0.001) with P content in the microaggregates. Furthermore, the partial least squares path model analysis indicated that biochar amendments directly increased P content (0.76 and 0.61) in micro- and macroaggregates, but the reduced P content by biochar was mainly derived from indirect effects, such as changed soil biological characteristics carbon (C)/P (-0.69), microbial biomass C (-0.63), microbial biomass P (-0.68), keystone taxa Proteobacteria (-0.63), and Ascomycota (-0.59), particularly for the macroaggregates. This study highlights that to some extent, biochar addition can reduce soil P content by affecting microbial communities (some keystone taxa), and soil biological characteristics at soil aggregate level.
胶体磷（P）在稻田土壤中会对水环境造成严重威胁。生物炭的添加不仅可以直接吸收 P 以减少径流损失，还可以为微生物群落创造热点，同时影响土壤 P。然而，尽管微生物起着至关重要的作用，但生物炭及其原料类型如何影响土壤微生物群落与土壤基质中的 P（如在土壤团聚体水平上）之间的关系仍然难以捉摸。为了解决这一知识空白，我们研究了生物炭对物理分离的土壤 P 各组分（包括微团聚体（53-250 μm）和大团聚体（250-2000 μm））的直接和间接影响。结果表明，与各自的对照相比，在 120 天的培养期后，秸秆和粪肥生物炭使微团聚体中土壤 P 含量降低了 55.2-56.7%，大团聚体中降低了 41.2-48.4%。真菌群落与大团聚体中 P 含量呈显著相关（0.34，p<0.05），而细菌群落与微团聚体中 P 含量呈极显著相关（0.66，p<0.001）。此外，偏最小二乘路径模型分析表明，生物炭的添加直接增加了微团聚体和大团聚体中 P 的含量（分别为 0.76 和 0.61），但生物炭降低 P 的含量主要来自间接效应，如土壤生物特性碳（C）/P（-0.69）、微生物生物量 C（-0.63）、微生物生物量 P（-0.68）、关键类群变形菌（-0.63）和子囊菌（-0.59）的变化，特别是对大团聚体。本研究表明，在一定程度上，生物炭的添加可以通过影响微生物群落（一些关键类群）和土壤团聚体水平上的土壤生物学特性来降低土壤 P 含量。
