• ISSN 1008-505X
  • CN 11-3996/S

鱼蛋白作为激发剂促进还田秸秆腐解和有机碳在土壤中积累

Using fish protein as activator to stimulate straw decompositionand enhance organic carbon accumulation in soil

  • 摘要:
    目的 秸秆还田量影响秸秆腐解、后茬作物生长和温室气体排放。研究不同秸秆还田量下,利用鱼蛋白作为激发剂促进秸秆分解、提高土壤有机碳积累的效果,为秸秆和鱼蛋白资源的合理高效利用提供理论依据。
    方法 采用室内培养试验方法,设置秸秆还田量、有机激发剂种类及其在总激发剂中的占比3个因素。秸秆还田量包括适量 (7500 kg/hm2)和高量 (10500 kg/hm2) 两个水平;供试有机激发剂包括猪粪、鱼蛋白;猪粪、鱼蛋白激发剂添加量占尿素氮量的比例分别为50%、100% (分别记为P50、F50、P100、F100),以两个秸秆还田量不添加激发剂处理为对照,共10个处理。激发剂总量按照调节投入秸秆碳氮比为35∶1所需要的氮量计算,其中50%和100%的氮量由猪粪、鱼蛋白提供,培养期为60天。培养期间测定CO2和N2O排放速率及累计排放量。培养结束时,测定土壤养分含量、细菌和真菌丰度以及酶活性。
    结果 高量秸秆还田虽然可增加土壤中有机碳的积累,但土壤CO2排放量以及单位输入碳的排放量均高于适量秸秆还田土壤。培养前13天,高量和适量秸秆还田的累计CO2排放量占总排放量的40%以上,以F50处理排放量最高。P50和F50处理适量和高量秸秆还田土壤CO2排放总量低于P100和F100处理,而N2O排放正好相反,P50和F50处理土壤有机碳积累也高于P100和F100处理。适量秸秆还田条件下,F50处理的CO2排放速率和N2O排放总量均高于P50;而CO2排放总量显著低于P50,土壤中有机碳积累量显著高于P50处理。适量秸秆还田土壤细菌和真菌丰度总体高于高量秸秆还田土壤;P50和F50处理土壤酶活性总体高于激发剂100%添加处理,F50处理的效果优于P50处理。
    结论 高量秸秆还田显著增加CO2排放总量,降低单位碳投入量的土壤有机碳积累量。适量秸秆还田(7500 kg/hm2)条件下,以鱼蛋白提供调节碳氮比所需氮量的50%处理较传统猪粪处理可显著提高早期CO2排放速率,降低CO2排放总量,提升土壤有机碳积累量,因此,可作为提高还田秸秆腐解的有效措施。

     

    Abstract:
    Objectives Straw returning amount to field affects the decomposition, greenhouse gas emission and the growth of following crops. We studied the suitable returning amount of rice straws and the effect of fish protein as activator to promote straw decomposition, from the points of greenhouse gas emission and organic carbon accumulation.
    Methods An indoor incubation experiment was conducted, three variables were included, as: straw returning with high and low amount (7500 and 10500 kg/hm2), organic activator source (fish protein and pig manure), and the percentage of organic activators (50% and 100%) in the total N required for rapid straw decomposition (regulating C/N ratio to 35∶1), and not regulating C/N ratio as the control for each returning amount, composing a total of 10 treatments, and the incubation lasted 60 days in total. During the incubation, the CO2 and N2O emission and cumulative emissions were monitored. At the end of incubation, soil nutrients, bacterial and fungal abundance and enzyme activities were measured.
    Results High straw returning amount resulted in higher total CO2 emissions and unit carbon input CO2 emissions than the moderate straw retuning, although the total organic carbon accumulation in soil was still high. The cumulative emissions during the first 13 days accounted for more than 40% of the total emission, F50 treatments (fish protein replacing 50% of the total activator N) resulted in the highest CO2 emissions under both straw retuning amount. Both F50 and P50 (pig manure replacing 50% of the total activator N) treatments were observed lower CO2 emissions than F100 and P100 (fish protein and pig manure provide 100% of the total activator N), but higher N2O emissions than F100 and P100. F50 and P50 treatment resulted in higher organic carbon accumulation in soil than F100 and P100 did. F50 was monitored higher CO2 emissions at early period of incubation, lower cumulative CO2 emissions at the end of incubation, and significantly higher organic carbon accumulation in soil than P50, while P50 resulted in higher soil nutrient contents, inducing higher nutrient availability of soil. High straw returning resulted in lower abundance of soil bacteria and fungi than moderate returning amount, and both F50 and P50 were recorded higher soil enzyme activities than the other treatments under the same straw returning amount.
    Conclusions Suitable straw returning amount is beneficial to the organic carbon accumulation per unit carbon input. Replacing 50% of N required for regulation of straw C/N ratio with fish protein could increase early decomposition of straws, decrease the total CO2 emissions, and enhance the organic carbon accumulation in soil, so is recommended for efficient straw returning practice.

     

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