论文部分内容阅读
为探究不同地表条件下农田土壤N_2O产生与释放对生物炭输入的响应,于2014~2015年小麦-玉米生长季,采用田间小区试验的方法,在不同生物炭用量[0 t·(hm~2·a)-1(CK)、5 t·(hm~2·a)-1(BC5)、45 t·(hm~2·a)-1(BC45)]及不同地表条件下[种植作物(以+表示)、裸地(以-表示)],对土壤N_2O释放、土壤铵态氮(NH_4~+-N)和硝态氮(NO_3~--N)的动态变化进行了观测分析.结果表明:(1)在小麦生长季,CK+、BC5+、BC45+这3个处理的土壤N_2O排放通量分别在21.70~88.91、21.42~130.09、64.44~179.58μg·(m~2·h)-1之间变动,BC45+处理显著高于其它2个处理(P<0.05).其中在小麦生长盛期(返青拔节期-孕穗抽穗期),3个处理的土壤N_2O排放通量均较小麦越冬期显著下降(P<0.05),而且BC45+处理基于CK+、BC5+的土壤N_2O排放通量增幅在小麦孕穗抽穗期已较其越冬期时分别降低了18.43%、14.62%.在玉米生长季前期,BC45+处理的土壤N_2O排放通量也显著高于BC5+和CK+处理(P<0.05),但至玉米的抽穗期及成熟期,BC45+处理的土壤N_2O排放通量已与BC5+和CK+无显著差异.这说明随作物生长盛期的到来及地表覆盖度的增加,生物炭介导的土壤N_2O排放的增加效应得以有效抑制.同期裸地条件下相同生物炭处理的土壤N_2O排放通量结果也证实了这一点.(2)在小麦生长季及其同期的裸地条件下,与CK相比,两种生物炭处理均可增加土壤NO_3~--N和NH_4~+-N含量,但在作物生育盛期,BC5+、BC45+处理的两种氮素形态较CK+处理均有下降,尤以BC45+最为突出,其土壤NO_3~--N和NH_4~+-N含量分别下降了96.44%、69.40%.玉米生长季与小麦季有着相近的趋势.较高生物炭施用量土壤NH_4~+-N和NO_3~--N含量在作物生育盛期的明显下降与同期土壤N_2O的排放显著减少相呼应.因作物生长发育对氮元素吸收增加致呼吸底物减少可能是生物炭介导下N_2O排放减少的原因之一.(3)在小麦生长季,生物炭施用提高土壤pH从4.62至最高5.18.至玉米季时,土壤的pH值在4.42~5.02之间波动,土壤pH值相对低时土壤N_2O的释放量相对高,反之亦然.土壤pH可在一定程度上影响土壤N_2O释放.
In order to explore the response of cropland N_2O production and release to biochar input under different surface conditions, field experiments were conducted in the wheat-corn growing season from 2014 to 2015 with different biochar contents [0 t · (hm ~ 2 (CK), 5 t · (hm ~ 2 · a) -1 (BC5) and 45 t · (hm ~ 2 · a) -1 (BC45)] under different surface conditions [ (+), Bare land (-)), the dynamic changes of soil N 2 O release, soil ammonium nitrogen (NH 4 + -N) and nitrate nitrogen (NO 3 ~ -N) were observed and analyzed.Results The results showed that: (1) In the wheat growing season, the N_2O fluxes of CK, BC5 + and BC45 + treatments were in the range of 21.70 ~ 88.91, 21.42 ~ 130.09 and 64.44 ~ 179.58μg · (m ~ 2 · h) (P <0.05) .While in wheat growth stage (returning to greening stage-booting stage), the fluxes of N 2 O in soil of three treatments were significantly lower than those in winter (P <0.05), and BC45 + treatment increased soil N 2 O fluxes based on CK + and BC5 + by 18.43% and 14.62%, respectively, at the booting heading stage of wheat compared with that at winter. In the early maize growing season, N2O emission flux is also significant (P <0.05), but at the heading and maturity stages of corn, there was no significant difference in N_2O fluxes between BC45 + and BC5 + and CK +, which indicated that with the arrival of peak crop growth and surface The increase effect of biochar-mediated increase of soil N 2 O emission can also be effectively inhibited by the increase of coverage, as can also be shown by the results of N 2 O 2 fluxes from the same biochar treated soil in the same period of bare land. (2) Compared with CK, both biochar treatments increased soil NO_3 ~ --N and NH_4 ~ + -N content in the bare land at the same period, but the two treatments of BC5 + and BC45 + The content of NO_3 ~ --N and NH_4 ~ + -N in soil decreased by 96.44% and 69.40%, respectively, compared with the CK + treatment. There was a similar trend between the growth season and the wheat season. The significant decrease of NH_4 ~ + -N and NO_3 ~ - N contents in soil at the high biochar application rate during the peak crop growth period echoes with the significant decrease of soil N_2O emission.Due to the increase of nitrogen uptake, Reduction may be biochar-mediated reduction of N_2O emissions caused by one of the reasons. (3) in wheat During the growing season, biochar application increased soil pH from 4.62 to a maximum of 5.18. By the maize season, soil pH fluctuated between 4.42 and 5.02, with a relatively high soil pH associated with relatively high N_2O release and vice versa. Soil pH can affect soil N 2 O release to a certain extent.