To improve carbon (C) sequestration and soil fertility of red soil, a two-year (2017 and 2018) field experiment was conducted to investigate the effects of two organic amendments (i.e., corn straw and sheep manure) applied alone or combined with biochar on soil nutrient content, enzyme activities involved in C cycling, and microbial substrate utilization rate in infertile red soil. There were six treatments, including control (non-amendment), corn straw, sheep manure and across biochar treatments (without and with biochar amendment, respectively). The organic amendments and biochar were applied in 2017 and 2018. The results showed that, compared with the control, organic amendments significantly increased soil pH, organic C, total nitrogen, available phosphorus and potassium contents. Compared with straw and manure alone, the biochar co-application with straw or manure significantly increased the contents of soil organic C, available potassium, and available nitrogen, without any significant interactive effects. Application of organic amendments significantly increased the activities of soil β-glucosidase (BG), cellobiohydrolase (CB), β-xylosidase (XYL), and peroxidase (PERO). The combined application of biochar and straw significantly reduced the activity of phenol oxidase (PHOX) by 28.6% and PERO by 22.2% in comparison with straw addition alone, respectively, while the combined application of biochar and manure significantly reduced the activities of α-glucosidase (AG) by 46.1%, BG by 50.9%, XYL by 41.6%, and PERO by 31.3% compared with manure addition alone, respectively. Compared with the control, the application of organic amendments significantly enhanced soil basal respiration and microbial utilization rates of carbohydrates, whereas biochar co-application significantly decreased microbial utilization rates of carbohydrates and carboxylic acids. Microbial C source utilization rates were significantly and positively correlated with the activities of BG and PERO. Thus, biochar co-application with organic amendments can enhance nutrient content and reduce enzymatic and microbial metabolic activities, thereby may facilitate C sequestration and fertility of infertile red soil.
为进一步促进红壤固碳培肥,于2017和2018年通过田间试验研究了两种有机物料(玉米秸秆和羊粪)单施以及与生物质炭配施对贫瘠红壤养分含量、碳转化相关酶活性和微生物底物利用速率的影响。试验设置6个处理,即不施有机物料(对照)、玉米秸秆、羊粪、单施生物质炭、玉米秸秆与生物质炭配施、羊粪与生物质炭配施。结果表明:与对照相比,有机物料施用显著增加了土壤pH值、有机碳、全氮、有效磷和速效钾含量;与单施秸秆和羊粪相比,生物质炭与秸秆或羊粪配施显著增加了土壤有机碳、速效钾和碱解氮含量,但两者无交互效应。与对照相比,有机物料施用显著提高了β-葡萄糖苷酶(BG)、纤维二糖水解酶(CB)、β-木聚糖苷酶(XYL)和过氧化物酶(PERO)活性;与单施秸秆相比,生物质炭与秸秆配施处理酚氧化酶、过氧化物酶活性分别显著降低了28.6%、22.2%;与单施羊粪相比,生物质炭与羊粪配施处理α-葡萄糖苷酶(AG)、BG、XYL和PERO活性分别显著降低了46.1%、50.9%、41.6%和31.3%。与对照相比,有机物料施用显著提高了土壤基础呼吸和微生物对碳水化合物的利用速率,而生物质炭配施处理对碳水化合物、羧酸类底物的利用速率存在显著抑制作用。微生物碳源利用速率与BG和PERO活性呈显著正相关。因此,有机物料与生物质炭配施更有利于提高土壤养分含量,降低有机碳分解酶和微生物碳源代谢活性,从而促进红壤固碳培肥,有利于贫瘠红壤的地力提升。.
Keywords: biochar; enzyme activity; microbial activity; organic amendment.