培肥措施对复垦土壤微生物碳氮代谢功能多样性的影响

    Effects of fertilization regime on the functional diversity of microbial carbon and nitrogen metabolism in reclaimed soil

    • 摘要: 土壤复垦是矿区生态环境恢复和耕地总量平衡及质量提升的根本要求。该研究依托山西襄垣采煤塌陷区定位复垦试验基地,采用Biolog-ECO方法和荧光定量PCR技术,研究了不施肥(CK)、单施化肥(CF)、单施有机肥(M)和有机无机培肥(MCF)4种培肥措施下复垦4 a和8 a土壤微生物碳代谢功能多样性及氮代谢功能基因丰度的变化特征。结果表明:随复垦年限增加,单施有机肥较其他处理可显著提高复垦土壤微生物的总碳源利用能力;不同处理复垦土壤微生物碳源相对利用率从高到低依次为氨基酸类、糖类、聚合物类、羧酸类、双亲化合物类、胺类,其中单施有机肥更大程度上提高了羧酸类、氨基酸类和胺类碳源的利用率;复垦年限和培肥措施没有改变复垦土壤微生物优势度指数,但有机无机配施较其他处理可显著提高香浓指数(H′)和Pielou均匀度指数;不同处理复垦土壤氮转化功能基因丰度总体从大到小依次表现为amoA(AOA)、amoA(AOB)、nisS、nirK、nifH,5种功能基因丰度均为以有机无机培肥处理最高,且随复垦时间增加而增加;复垦土壤有机质含量与nirS、nirK、nifH基因丰度以及平均颜色变化率(Average Well Color Development, AWCD)值存在显著相关性,相关系数在0.707~0.807,同时5种氮转化功能基因丰度均与玉米产量存在显著或极显著的相关性,相关系数在0.824~0.949。综上所述,单施有机肥可提高土壤有机质含量,进而增强了复垦土壤碳代谢强度,有机无机培肥则更有利于复垦土壤碳氮代谢功能多样性的提升,并促进作物产量形成。

       

      Abstract: Abstract: Soil reclamation has become a fundamental requirement for ecological environment restoration, total dynamic balance of cultivated land resources, and soil quality improvement in mining areas. This study was carried out at the long-term reclaimed base of a coal mining subsidence area in Xiangyuan county, Shanxi province, China. Surface soil samples of 0-20 cm were collected under various fertilization regimes in the 4- and 8-year experiment. Biolog-ECO and qPCR technologies were used to investigate the effect of various fertilization regimes on the soil microbial functional diversity of carbon metabolism, and functional gene abundance of nitrogen metabolism. Four fertilization treatments were applied within each reclamation stage, including no fertilizer (CK), chemical fertilizer only (CF), manure only (M), and 50% chemical fertilizers co-applied with 50% manure (MCF). The results showed that the M treatment can significantly improve the ability of soil microorganisms to utilize total carbon sources, compared with other treatments with the increase of reclamation years. The relative utilization rate of microorganism to carbon sources in reclaimed soil under various treatments were successively amino acids, carbohydrate, polymers, carboxylic acids, amine and miscellaneous from high to low. The M treatment improved the utilization rate of carboxylic acids, amino acids, and amines to a greater extent than those of other carbon sources. The differences of microbial carbon metabolism between various fertilizer treatments were mainly concentrated in five kinds of sugars, (including I-Erythritol, D-Mannitol, N-Acetyl-D-glucosamine, D-Cellobiose and α-D-Lactose), and four amino acids (including L-Arginine, L-Asparagine, L-Serine and L-Threonine). No significant change was observed in the Simpson index (D) under various reclamation years and fertilization regimes, indicating that the fertilization measures and reclamation years did not contribute to the dominant distribution of soil microbial physiological groups. The MCF treatment significantly improved the Shannon-wiener index (H') and Pielou evenness index (J), compared with other treatments. The functional gene abundance of nitrogen conversion was ranked in a descend order: amoA (AOA) > amoA (AOB) >nisS, nirK> nifH, in the reclaimed soil under various treatments. It infers that the nitrification was stronger than the denitrification and nitrogen fixation in the nitrogen cycle process of reclaimed soil. The abundance of five functional genes in the MCF treatment was the highest than that in other treatments, where increasing with the increase of reclamation time. The increase amplitude of amoA gene of AOA and AOB was the highest, indicating that the amoA gene was more sensitive than other functional genes to environmental factors, such as fertilization. The content of organic matter was significantly correlated with the abundance of nirS, nirK, nifH genes, and AWCD values in reclaimed soil, where the correlation coefficient was 0.707-0.807. Meanwhile, the abundance of five nitrogen conversion function genes was significantly or extremely significantly correlated with maize yield, where the correlation coefficient was between 0.824-0.949. Single application of manure can significantly increase the content of soil organic matter, and then enhance the intensity of microbial carbon metabolism, while, the combination of manure and chemical fertilizer was more conducive to improve the function diversity of carbon and nitrogen metabolism in reclaimed soil, and thereby to promote the crop yield.

       

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