| 生物炭介导的不同地表条件下土壤N2O的排放特征 |
| 摘要点击 3847 全文点击 1583 投稿时间：2016-06-21 修订日期：2016-11-29 |
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| 中文关键词 生物炭 N2O 硝态氮 铵态氮 地表覆盖 |
| 英文关键词 biochar nitrous oxide nitrate nitrogen ammonium nitrogen land cover |
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| 中文摘要 |
| 为探究不同地表条件下农田土壤N2O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·（hm2·a）-1（CK）、5 t·（hm2·a）-1（BC5）、45 t·（hm2·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N2O释放、土壤铵态氮（NH4+-N）和硝态氮（NO3--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N2O排放通量分别在21.70~88.91、21.42~130.09、64.44~179.58μg·（m2·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N2O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N2O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N2O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N2O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N2O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N2O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NO3--N和NH4+-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NO3--N和NH4+-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NH4+-N和NO3--N含量在作物生育盛期的明显下降与同期土壤N2O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N2O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N2O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N2O释放. |
| 英文摘要 |
| It was aimed to investigate the response to biochar addition on N2O gas production and emission in different surface conditions. To study the dynamic changes of soil N2O release, soil nitrate(NO3--N) and ammonium(NH4+-N), a field trials experiment was conducted from 2014 to 2015 in wheat and corn season, which contained three treatments[the blank control group (CK), biochar applied at 5 t·(hm2·a)-1(BC5) and 45 t·(hm2·a)-1(BC45), respectively] under crop cultivation(+) and non-cultivation(-) condition. The results indicated that:1 During the season of wheat growth, the soil N2O emissions of CK+, BC5+, BC45+ were 21.70-88.91, 21.42-130.09, 64.44-179.58 μg·(m2·h)-1 respectively, and that of BC45+ possessed a higher value than those of the other treatments(P<0.05). Compared with wheat winter period, the soil N2O emissions of the three treatments decreased evidently in wheat peak stage(returning green and jointing stage, booting and heading stage) (P<0.05), and the amplification of BC45+ reduced by 18.43% and 14.62% in comparison with CK+ and BC5+ in wheat booting and heading stages. In the early stage of maize growth, the soil N2O emissions of BC45+ were significantly increased compared with CK+ and BC5+(P<0.05). However, there were no significant differences among treatments of maize heading stage and mature stage. It showed that the biochar-mediated promotion effect of soil N2O emissions was effectively inhibited by crop growth and the increase of surface mulch. Besides, the result of soil N2O release in the same treatment had also confirmed this conclusion in bare land. 2 Under the conditions of wheat cultivation and homochronous non-cultivation, the soil NO3--N and NH4+-N contents of BC5+ and BC45+ treatments were raised with respect to CK+, but the values dropped significantly in wheat peak stage, especially for BC45+ treatment, with 96.44% and 69.40% decrease respectively. The soil inorganic nitrogen content of maize growth season had a similar trend in wheat season. Parallel to this result of the apparently falling soil NO3--N and NH4+-N concentrations, the soil N2O emissions of BC45+ also declined remarkably in peak stage. The decline in respiratory substrate caused by the increase of nitrogen uptake by crop growth, may be one of the reasons for the decrease of N2O emission. 3 In wheat growth season, the soil pH values of the biochar treatments were improved from 4.62 to 5.18. In maize season, the soil pH values ranged from 4.42 to 5.02. When the soil pH value was relatively low, the soil N2O emission was high, and vice versa. The soil N2O emission was partly influenced by the soil pH value. |
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