秸秆还田与生物炭施用影响黑土有机质并缓解土壤酸化

Effects of Straw Returning and Biochar Application on Soil Organic Matter and Mitigate Soil Acidification of Black Soil

针对黑土“变瘦”、土壤有机质(SOM)下降和酸化问题,通过2年田间原位模拟试验,采用^(13)C-核磁共振及差热与热重分析技术,研究了模拟秸秆还田与生物炭施用对SOM量、质以及缓解酸化的影响。基于连续2年秸秆全量还田,设8个处理:无秸秆和生物炭添加为对照(ck);0~15 cm土层土壤与秸秆混合(SI15,模拟秸秆浅旋还田);0~35 cm土层土壤与秸秆混合(SI35,模拟秸秆深混还田);25~35 cm土层4倍量秸秆埋置(SEDI,模拟秸秆富集深还);5~15 cm土层秸秆埋置(SE15,模拟秸秆浅翻压还田局部区域与土壤不混合);25~35 cm土层秸秆埋置(SE35,模拟秸秆深翻压还田局部区域与土壤不混合);0~15 cm土层土壤与4 t/hm^(2)生物炭混合(BC4)以及与12 t/hm^(2)生物炭混合(BC12,模拟生物炭还田)。结果表明:与ck相比,SI15、BC4和BC12处理显著提高SOM含量16.26%~30.35%。SI15、SI35、SEDI、BC4和BC12处理显著增加土壤pH 0.12~0.28,施用生物炭对缓解土壤酸化作用最大。添加秸秆和生物炭对SOM结构特征影响不同,SI15和SI35使SOM的脂族性和亲水性得到发展,有利于提高SOM活性,发挥土壤肥力,而BC4和BC12提高SOM的芳香性和疏水性,有利于碳封存。SOM提升对缓解土壤酸化具有显著效应。

In order to solve the problems of black soil"thinning",soil organic matter(SOM)decline and acidification,the influencing mechanism of simulated straw returning and biochar application on SOM quantity,quality and acidification alleviation was studied by using ^(13)C-cross-polarization-magic angle rotation NMR(^(13)C-CP/MAS NMR)and differential thermal and thermogravimetric analysis technology through a 2-year field in-situ simulation tests.Based on the full amount of straw returning to soil for 2 consecutive years,eight treatments were set up:no addition of straw and biochar(ck),mixing of soil and straw in 0-15 cm soil layer(SI15,simulation of straw shallow rotation returning),mixing of soil and straw in 0-35 cm soil layer(SI35,simulation of straw deep-mixing returning);burying of the quadruple amount of straw in 25-35 cm soil layer(SEDI,simulation of straw enrichment and deep returning),burying of straw in 5-15 cm soil layer(SE15,simulation of straw shallow tilling and pressing without mixing with soil in some local areas),burying of straw in 25-35 cm soil layer(SE35,simulation of straw deep tilling and pressing without mixing with soil in some local areas),mixing of 0-15 cm soil layer with 4 t/hm^(2) biochar(BC4)and 12 t/hm^(2) biochar(BC12,simulation of biochar returning).The results showed that SI15,BC4 and BC12 treatments significantly increased SOM content by 16.29%-30.38%,compared with ck.Moreover,SI15,SI35,SEDI,BC4 and BC12 treatments significantly increased soil pH by 0.12-0.28 units.Biochar addition had the greatest effect on soil acidification mitigation.The addition of straw and biochar had different effects on the structural characteristics of SOM.SI15 and SI35 developed the aliphatic and hydrophilic nature of SOM,which was conducive to improving SOM activity and enhancing soil fertility,while BC4 and BC12 improved the aromatic and hydrophobic nature of SOM,which was conducive to carbon sequestration.The improvement of SOM has a significant ameliorative effect on mitigating soil acidification.