长期施用生物炭对棕壤养分及腐殖质组分的影响

Effects of Long-Term Application of Biochar on Nutrients,Fractions of Humic in Brown Soil

【目的】研究长期施用生物炭对棕壤养分含量及腐殖质组分含量的影响,为评价生物炭在提高土壤肥力水平和调控土壤腐殖质组成及稳定性方面的长效作用提供科学依据。【方法】以生物炭田间定位试验为基础,采用随机区组设计,设置4个施炭量处理:0(CK)、15.75 t·hm^(-2)(BC1)、31.50 t·hm^(-2)(BC2)和47.25 t·hm^(-2)(BC3),分别测定生物炭施用4年和8年后土壤有机碳(SOC)、氮磷钾速效养分、氮磷钾全量养分以及土壤富里酸(FA)、胡敏酸(HA)和胡敏素(HM)含量。【结果】施用生物炭可提高SOC含量,BC1、BC2、BC3处理SOC含量较CK处理提高了37.35%—72.97%。施用生物炭显著提高了土壤速效钾(AK)含量,与CK处理相比,BC1、BC2和BC3处理土壤AK含量较CK处理分别提高了11.67—14.00、19.33—22.33和12.33—35.33 mg·kg-1。施用生物炭对土壤全氮(TN)、碱解氮(AN)、全磷(TP)、速效磷(AP)和全钾(TK)含量影响不大(除个别处理)。施用生物炭显著提高了土壤HA、可溶性腐殖质(HE)和HM含量。与CK处理相比,BC1、BC2和BC3处理土壤HA含量分别提高了39.68%—40.91%、30.91%—50.79%和34.55%—57.14%。BC1、BC2和BC3处理土壤HE含量较CK处理分别提高18.02%—29.74%、16.81%—30.48%和15.92%—24.91%。与CK处理相比,BC1、BC2和BC3处理土壤HM含量分别提高了48.39%—58.94%、13.57%—89.23%和82.36%—105.82%。施用生物炭4年后对土壤FA含量无显著影响,但施用生物炭8年后显著提高了土壤FA含量,BC1、BC2和BC3处理较CK处理分别提高了22.01%、30.19%和18.24%。在2016年,各施炭处理提高了土壤HA/HE和HA/FA,但降低了HE/HM,但在2020年,仅BC1处理显著提高了土壤HA/FA,BC3处理显著降低了HE/HM。通过冗余和相关分析表明,SOC、TK、AK、TP和AP与腐殖质组分含量存在显著的正相关关系;SOC和TK与土壤腐殖质的稳定性呈显著正相关关系,但土壤SOC、AK、TP和AP与土壤腐殖质的活性呈显著负相关关系。【结论】长期施用生物炭可改善土壤养分状况,主要表现在提高SOC和AK含量;长期施用生物炭可提高土壤腐殖质组分的含量,主要表现在提高土壤HA和HM含量,但对土壤腐殖质稳定性的影响会随时间推移被减弱;土壤养分含量与土壤腐殖质组分含量及稳定性存在显著正相关关系。

【Objective】The aim of this study was to investigate the effects of long-term application of biochar on nutrient content and humus component content in brown soil,so as to provide the scientific basis for evaluating the long-term effects of biochar on improving soil fertility level and regulating soil humus composition and stability.【Method】Based on the field positioning experiment of biochar,using a randomized block design four carbon application treatments were set up:0(CK),15.75 t·hm^(-2)(BC1),31.5 t·hm^(-2)(BC2)and 47.25 t·hm^(-2)(BC3).The soil organic carbon,available nitrogen,phosphorus,potassium nutrients,total nitrogen,phosphorus,potassium nutrients and soil fulvic acid(FA),humic acid(HA),humin(HM)content were measured after 4 and 8 years of biochar application,respectively.【Result】The application of biochar could increase the SOC content,and the SOC content under BC1,BC2,and BC3 treatments increased by 37.35%to 72.97%than that under CK treatment.The application of biochar significantly increased the soil available potassium(AK)content;compared with CK treatment,the soil AK content of BC1,BC2 and BC3 treatments increased by 11.67-14.00 mg·kg-1,19.33-22.33 mg·kg-1 and 12.33-35.33 mg·kg-1,respectively.The application of biochar had little effect on soil total nitrogen(TN),alkali hydrolyzed nitrogen(AN),total phosphorus(TP),available phosphorus(AP)and total potassium(TK)content(except for individual treatments).The application of biochar significantly increased the content of soil HA,humus-extractable(HE),and HM.Compared with CK treatment,the soil HA content under BC1,BC2,and BC3 treatments increased by 39.68%-40.91%,30.91%-50.79%and 34.55%-57.14%,respectively.Compared with CK treatment,the soil HA content under BC1,BC2,and BC3 treatments increased by 39.68%-40.91%,30.91%-50.79%and 34.55%-57.14%,respectively.Compared with CK treatment,the soil HE content of BC1,BC2 and BC3 treatments increased by 18.02%-29.74%,16.81%-30.48%and 15.92%-24.91%,respectively.Compared with CK treatment,the soil HM content of BC1,BC2,and BC3 treatments increased by 48.39%-58.94%,13.57%-89.23%and 82.36%-105.82%,respectively.After applying biochar for 4 years,there was no significant effect on soil FA content,but after applying biochar for 8 years,the soil FA content significantly increased,with BC1,BC2,and BC3 treatments increasing by 22.01%,30.19%and 18.24%,respectively,compared with CK treatment.In 2016,the various carbon application treatments increased soil HA/HE and HA/FA,but decreased HE/HM;but in 2020,only BC1 treatment significantly increased soil HA/FA,while BC3 treatment significantly reduced HE/HM.Through redundancy and correlation analysis,there was a significant positive correlation between SOC,TK,AK,TP and AP and the content of humic substances;There was a significant positive correlation between SOC and TK and the stability of soil humus substances,however,there was a significant negative correlation between SOC,AK,TP,and AP and the activity of soil humus substances.【Conclusion】Long term application of biochar could improve soil nutrient status,mainly manifested in increasing SOC and AK content.Long term application of biochar could increase the content of humus components in soil,mainly manifested in increasing the content of soil HA and HM,however,the impact on the stability of soil humus would weaken over time.There was a significant positive correlation between soil nutrient content and soil humus component content and stability.