Effects Of Biochar-based And Chemical Fertilizer On The Soil Respiration In Moso Bamboo(Phyllostachys Edulis) Plantations

The planting area of Moso Bamboo?Phyllostachys edulis?in China has exceeded 4.4 millions hectares,which is an important forest resource in the subtropical region.In order to promote the growth of bamboo and increase the economic benefits of the bamboo industry,the intensive management method?mainly fertilization,tillage and removal of understory vegetation?was adopted by farmers to manage the bamboo forest.It is well known that long-term intensive management will not only lead to the reduction of soil organic carbon storage and soil enzyme activities,but also the consequences of increased greenhouse gas emissions.As a new type of fertilizer,biochar-based fertilizer has the functions of improving soil physical properties,increasing soil nutrient content and reducing greenhouse gas emissions.However,the mechanisms of the application of biochar-based fertilizer?BF?to soil respiration and its components in subtropical plantations are still unclear.In this experiment,the effects of different fertilizer treatments?biochar-based fertilizer,chemical fertilizer?CF?and a 50:50mixture of BF and CF?BCF??on soil respiration components and soil environmental factors?soil temperature and soil moisture content,soil labile carbon pool,and soil enzyme activities?of bamboo plantation were studied through a one-year field trial.The purpose of this study was to investigate the mechanisms of the effects of biochar-based fertilizers and chemical fertilizers on soil respiration components of Moso bamboo plantation,and to reveal the relationship between soil respiration components and soil environmental factors in bamboo plantation under different fertilizer treatment.?1?Under the application of control?Control?,biochar-based fertilizer,chemical fertilizer,and a50:50 mixture of BF and CF,soil respiration?R_S?rate and heterotrophic respiration?R_H?rate showed significant seasonal variation characteristics,with the highest values occurring in summer and the lowest in winter.The application of CF and BCF significantly increased the annual mean values of R_S and the cumulative CO₂ emissions?P<0.05?,but the application of BF had no significant effect on it;the application of BF significantly reduced the annual mean values of R_H and the cumulative CO₂emissions?P<0.05?,and the application of CF significantly increased the annual mean values of R_H and the cumulative CO₂ emissions?P<0.05?,but the application of BCF had no significant effect on it.All fertilizer treatments notably increased annual mean values and annual cumulative R_A but the largest effect size occurred in the CF treatment?P<0.05?.The application of all three fertilizers significantly increased the annual mean values of soil autotrophic respiration?R_A?and the cumulative CO₂ emissions?P<0.05?.?2?Different fertilization treatments in bamboo forest·had no significant effect on soil temperature and soil moisture content.Under the control,BF,CF and BCF treatment,soil water-soluble carbon?WSOC?and microbial biomass carbon?MBC?concentrations showed significant seasonal variation characteristics,with the highest value appeared in September and the lowest value appeared in January to February.Compared with the control,the application of BF,CF and BCF increased the annual mean values of soil WSOC concentrations by 13.3%,4.9%and 11.0%?P<0.05?,respectively,and increased the annual average values of soil MBC concentrations by 12.0%,6.8%and 8.9%?P<0.05?,respectively.Compared with the control,the application of CF and BCF increased the annual average of soil invertase activity by 15.2%and 9.5%?P<0.05?,respectively,and increased the annual average values of soil?-glucosidase activity by 16.7%and 7.6%?P<0.05?,respectively.The application of BF decreased the annual average of soil invertase activity and?-glucosidase activity by 8.2%and 6.3%?P<0.05?,respectively.?3?Under all fertilization treatments,soil R_S,R_H and R_A showed significant exponential relationship with soil temperature of 5 cm depth?P<0.05?.Under the control,BF,CF and BCF treatment,the temperature sensitivity coefficient(Q₁₀)of soil R_S in Moso bamboo plantation was 2.02,2.13,2.13 and 1.92,respectively,the Q₁₀ values of soil R_H were 2.47,2.47,3.03 and 2.50,respectively,and the Q₁₀ values of soil R_A were 1.36,1.83,1.34 and 1.34,respectively.The sensitivity of soil R_H to temperature was significantly higher than that of R_A.In this experiment,the application of BF significantly increased the Q₁₀ values of soil R_A,and the application of CF significantly increased the Q₁₀ values of soil R_H.In this experiment,there was no correlation between soil R_S,R_H and R_A and soil moisture content in Moso bamboo plantation.In this experiment,under all fertilization treatments,soil R_S and R_H were significantly correlated with concentrations of soil WSOC and MBC,and activities of soil invertase and?-glucosidase?P<0.05?.There was a significant correlation between soil R_A and soil invertase activity?P<0.05?.A significant correlation between soil R_A and soil WSOC and MBC concentrations occurred only in BCF treatment?P<0.05?.There was a significant correlation between soil R_A and the activity of?-glucosidase in BF and BCF treatments?P<0.05?.In conclusion,compared with the conventional chemical fertilizer use,the novel management practice of biochar-based fertilizer application offers advantages,such as reducing soil C emissions and increasing SOC content,which has the implication of mitigating soil greenhouse gas emissions in subtropical Moso bamboo plantations.