生物质炭配施有机物料对红壤碳组分及酶生态化学计量特征的影响

Effects of biochar combined with organic amendments on carbon composition and eco-enzymatic stoichiometry of red soil

【目的】分析生物质炭和有机物料施用对旱地红壤有机碳组分和酶活性的影响,探明微生物的碳氮磷元素限制特征,为提升红壤有机碳稳定性提供理论依据。【方法】采用田间试验,设置不施有机物料对照(ck)、玉米Zea mays秸秆单施、羊粪单施及其分别与生物质炭(玉米秸秆炭)配施等6个处理。试验开始2 a后测定土壤有机碳组分、土壤养分质量分数、碳氮磷循环相关碱解酶活性和氧化酶活性。【结果】与单施秸秆和羊粪相比,生物质炭与有机物料配施显著增加了土壤有机碳和碱解氮质量分数(P<0.05),提高了土壤碳氮比和碳磷比及惰性碳组分质量分数,降低了有机碳活性指数。有机物料施用显著提高了纤维二糖水解酶(CB)、β-1,4-N-乙酰氨基葡萄糖苷酶(NAG)和过氧化物酶(PERO)活性(P<0.05);与单施羊粪相比,生物质炭与羊粪配施处理显著降低β-葡萄糖苷酶(BG)活性50.9%、亮氨酸氨基肽酶(LAP)活性32.1%、NAG活性45.3%、酸性磷酸酶(PHOS)活性40.0%(P<0.05)。与单施秸秆相比,生物质炭与秸秆配施降低了多酚氧化酶(PHOX)活性28.6%和PERO活性22.2%,但对其他酶的活性无影响。与单施秸秆相比,生物质炭配施秸秆降低了向量长度;与单施羊粪相比,生物质炭配施羊粪对酶化学计量比、向量长度及向量角度均无显著影响。PERO和PHOX与土壤惰性碳质量分数、碳氮比、碳磷比呈显著负相关(P<0.05)。冗余分析表明:土壤惰性碳质量分数、碳氮比和碳磷比是影响土壤酶活性及其化学计量特征的主要因子。【结论】与有机物料单施相比,生物质炭与有机物料配施可以更好地提高旱地红壤养分和惰性碳组分质量分数,降低有机碳分解酶活性,缓解碳磷限制,可作为改善红壤微生物养分限制和提高碳汇能力的有效措施。

[Objective]The objective is to analyze the effects of biochar and organic amendments application on organic carbon composition and enzyme activities of red soil in arid areas,and investigate limiting characteristics of microbial nutrients,so as to provide a theoretical basis for improving the stability of red soil organic carbon.[Method]A field experiment with 6 treatments were set up,including a non-amendment control(ck),corn(Zea mays)straw and sheep manure single application and their combination with biochar(corn straw biochar).2 years after the start of the experiment,soil organic carbon components,soil nutrient mass fraction,hydrolase activities and oxidase activities related to carbon,nitrogen and phosphorus cycling were determined. [Result] Compared with the single application of straw and sheep manure, the combination of biochar and its application significantly increased the mass fraction of soil organic carbon and available nitrogen (P<0.05), increased the soil carbon-nitrogen ratio (C∶N), carbon-phosphorus ratio (C∶P) and the mass fraction of recalcitrant carbon pools, and reduced soil organic carbon activity index. The application of organic amendments significantly increased the activities of β-D-cellobiosidase hydrolase (CB), β-1,4-N- acetylglucosacosidase (NAG) and peroxidase (PERO) (P<0.05). Compared with the single application of sheep manure, the combined application of biochar and sheep manure significantly reduced the β-glucosidase (BG) activity, leucine aminopeptidase (LAP) activity, NAG activity and acid phosphatase (PHOS) activity (by 50.9%, 32.1%, 45.3% and 40.0%, respectively, P<0.05). Compared with the single application of straw, the combined application of biochar and straw reduced the activity of polyphenol oxidase (PHOX) by 28.6% and PERO activity by 22.2%, but had no effect on the activity of other enzymes. Compared with the single application of straw, the combination of biomass charcoal and straw reduced the vector length. Compared with applying sheep manure alone, the combination of biomass charcoal and sheep manure had no significant effect on enzyme stoichiometry, vector length, and vector angle (P< 0.05). PERO and PHOX were significantly negatively correlated with soil recalcitrant carbon pools, C∶N and C∶P (P<0.05). Redundant analysis showed that soil recalcitrant carbon pools, C∶N and C∶P were the main factors affecting soil enzyme activity and its stoichiometric characteristics. [Conclusion] Compared with the single application of organic materials, the combined application of biochar and sheep manure can better improve the nutrient and the size of recalcitrant carbon fraction in red soil in arid cropland, reduce the activity of carbon degrading enzymes, and alleviate microbial carbon and phosphorus limitation, and can be an effective measure to improve the microbial nutrient limitations and carbon sequestration capacity in red soil.