增施磷石膏与不同耕作措施对碱土碳库和微生物群落结构的影响

Effects of phosphogypsum on carbon pool and microbial community of Solonetz under different tillage measures

盐碱地作物苗期遇降雨或漫灌容易导致土壤结皮,使土壤碳库代谢受阻、微生物生存环境恶化,为阐明施用磷石膏后旋耕、深松、镇压措施对碱土碳库及微生物群落的影响,利用大田试验,设磷石膏+旋耕处理(CA),磷石膏+旋耕+苗期浅松处理(QCA),磷石膏+旋耕+苗期镇压处理(ZCA),以不施磷石膏+旋耕处理为对照(CK),通过土壤pH、电导率、有机碳、无机碳及细菌、真菌群落结构揭示其变化规律。研究表明,施用磷石膏显著降低土壤pH、CaCO3含量,pH降幅以QCA处理最大、CaCO3降幅以ZCA处理最大;施用磷石膏可显著提高ZCA的土壤活性有机碳(DOC)、土壤微生物生物量碳(MBC)含量;磷石膏处理使总有机碳增加,增幅4.11%~6.45%;磷石膏显著增加可溶性K^(+)、Ca^(2+)含量,降低Na+含量。磷石膏可提高土壤变形菌门、拟杆菌门相对丰度,变形菌门较CK提高30.66%~34.75%,拟杆菌门较CK可提高21.79%~53.55%,以ZCA处理增幅最为显著;Spearman分析发现,变形菌门与土壤K^(+)呈极显著正相关、与Na+呈显著负相关。真菌主要优势菌门为子囊菌门、担子菌门、罗兹菌门,CA、ZCA处理子囊菌门的丰度较CK分别提高2.64%、3.98%,各处理担子菌门丰度较CK提高0.65%~9.44%;磷石膏可提高土壤镰刀菌属、被孢霉属相对丰度。Spearman相关性研究发现子囊菌门与土壤pH呈显著负相关,与土壤K^(+)呈显著正相关;罗兹菌门与土壤Ca^(2+)呈显著正相关。ZCA处理可有效降低土壤pH,提高土壤DOC、MBC含量,改变微生物群落组成与结构,为科学指导盐碱地农业生产提供依据。

Rain or flood irrigation in the seedling stage of saline alkali land crops can lead to soil crusting,which leads to blocked soil carbon pool metabolism and deterioration of microbial living environment.In order to clarify the impact of rotary tillage,subsoiling and suppression measures on soil carbon pool and microbial community with phosphogypsum,a field experiment was conducted with four treatment:phosphogypsum+rotary tillage treatment(CA),phosphogypsum+rotary tillage+shallow loosening treatment at seedling stage(QCA),phosphogypsum+rotary tillage+suppression at seedling stage(ZCA),and rotary tillage without phosphogypsum as control(CK).The change rules of soil pH,EC,organic carbon,inorganic carbon and bacterial and fungal community structure were revealed.The results showed that the application of phosphogypsum significantly reduced soil pH and CaCO3 content,with QCA and ZCA treatment being the largest in pH and CaCO3,respectively;Application of phosphogypsum significantly increased soil labile organic carbon(DOC)and soil microbial biomass carbon(MBC)contents of ZCA treatment;Phosphogypsum treatment increased the total organic carbon by 4.11%-6.45%;Phosphogypsum significantly increased the content of soluble K^(+),Ca^(2+)and decreased the content of Na+.Phosphogypsum increased the relative abundance of Proteobacteria and Bacteroidetes in soil.Proteobacteria and Bacteroidetes increased by 30.66%-34.75%and 21.79%-53.55%,respectively,compared with CK,with ZCA treatment increasing the most significantly.Spearman’s analysis found that Proteobacteria had a very significant positive correlation with soil K^(+)and a significant negative correlation with Na+.The main dominant phyla of fungi were Ascomycota,Basidiomycota and rhodium.The abundance of Ascomycota in CA and ZCA treatments was 2.64%and 3.98%higher than CK,and the abundance of Basidiomycota in each treatment was 0.65%to 9.44%higher than CK,respectively.Phosphogypsum increased the relative abundance of Fusarium and Mortierella in soil.Spearman correlation study found that Ascomycota was significantly negatively correlated with soil pH and positively correlated with soil K^(+);Rozellomycota was significantly positively correlated with soil Ca^(2+).ZCA treatment can effectively reduce soil pH,increase soil DOC and MBC contents,change microbial community composition and structure,and provide a basis for scientific guidance of saline alkali land production.