|Alternative Title||Soil Organic Carbon Losses and Influential Factors on Sloping Cropland of Purple Soil|
|Place of Conferral||北京|
|Keyword||紫色土 土壤有机碳 Ch4 Co2 径流损失|
利用紫色土坡耕地Lysimeter装置开展土壤有机碳气体排放（CH4和CO2）及其随径流迁移损失的同步观测，获得了紫色土坡耕地土壤有机碳的损失途径、通量及其相互关系，主要研究结果与结论如下：（1）施肥对紫色土坡耕地土壤的CH4和CO2排放均有显著影响，施肥显著抑制紫色土坡耕地土壤吸收大气CH4的能力，但促进CO2的排放。常规施肥NPK处理土壤在小麦季、玉米季以及全年内的CH4平均排放速率分别为-22.86±3.47 μg(C)?m-2?h-1、-35.20±6.58 μg(C)?m-2?h-1，-29.96±5.26 μg(C)?m-2?h-1，累计排放通量分别为-0.79±0.01 kg(C)?ha-1、-0.95±0.10 kg(C)?ha-1和-1.74±0.09 kg(C)?ha-1。各施肥处理土壤均表现为CH4吸收汇，其CH4排放速率和累计排放通量均差异显著（P<0.01），但施肥显著抑制紫色土坡耕地土壤吸收大气CH4的能力。试验期内5种施肥处理的CH4吸收速率和累计吸收通量均显著低于无肥CK处理（P<0.05），其原因可能与铵态氮肥所释放的NH4+以及由NH4+快速转化而来的NO3-的富集对甲烷氧化菌活性的抑制有关。常规施肥NPK处理在小麦季、玉米季和全年内的CO2平均排放速率分别为18.43±1.56 mg(C)?m-2?h-1、79.77±5.13 mg(C)?m-2?h-1和45.69±4.18 mg(C)?m-2?h-1，累计排放通量分别为745.94±97.90 kg(C)?ha-1、2121.53±103.94 kg(C)?ha-1和2867.47±201.65 kg(C)?ha-1。各施肥处理间的CO2排放速率和CO2累计排放通量差异显著（P<0.01），所有施肥处理的CO2排放速率和累计排放量均显著高于无肥对照处理，说明施肥能显著促进土壤CO2的排放。（2）土壤可溶性有机碳（DOC）含量是紫色土坡耕地土壤CH4排放的主要影响因子，而影响CO2排放环境因子除DOC外，还包括土壤温度、湿度及NO3--N含量。（3）壤中流是紫色土坡耕地土壤DOC的主要径流损失途径，壤中流DOC损失通量占径流DOC损失总量的70%以上。NPK处理的地表流和壤中流累计径流量分别为1.28±0.06 m3和5.84±0.33 m3，径流总量为7.13±0.34 m3。紫色土坡耕地系统土壤壤中流发育，壤中流径流量约占总径流量的69.1%-88.8%。年度泥沙损失通量为628.2±173.9 kg?ha-1，地表径流、壤中流DOC损失通量及径流DOC总损失通量分别为9.35±2.40 kg?ha-1、1.02±0.01 kg?ha-1和10.37±2.40 kg?ha-1。壤中流DOC损失通量占径流DOC损失总量的70%以上，说明壤中流是土壤可溶性有机碳（DOC）的主要损失途径。（4）紫色土坡耕地土壤有机碳损失主要包括CO2排放、径流和泥沙损失, CO2排放是土壤有机碳损失的主要途径。NPK处理土壤有机碳损失通量总量为2888.94±201.81 kg?ha-1，其中，以CO2排放和径流、泥沙形式损失的通量分别为2867.47±201.65 kg?ha-1、10.37±2.40 kg?ha-1和6.42±1.78 kg?ha-1，分别占土壤有机碳损失通量总量的99.41%、0.41%和0.13%。其他各施肥处理CO2排放损失的土壤有机碳均占总量的98%以上，表明CO2排放是土壤有机碳损失的主要途径。（5）土壤有机碳的CO2排放和径流损失间存在负相关关系，可能与土壤有机碳活性组分含量有关。;
In this study, the coupling research on characteristics and fluxes of carbon loss via hydrological and gaseous pathways on sloping cropland had been conducted useing the free-drain lysimeter in slopping cropland of purple soil. Impacts of six fertilization treatments which involved single manure (OM), manure combined with NPK (OMNPK), straw combined with NPK (RSDNPK), conventional NPK fertilizer (NPK), single nitrogen (N) and control (CK) on both aqueous and gaseous carbon loss were studied. Observations and conclusions are made as follows:(1) In contrast to CK, fertilization had a significant(P<0.05) impact on CH4 and CO2 emission, the application of fertilizer inhibited purple soil to absorb atmospheric CH4, but promoted the emission of CO2, significantly.The average CH4 emission rate and accumulation of NPK treatment was -22.86±3.47 μg (C)?m-2?h-1 and -0.79±0.01 kg (C)?ha-1 in wheat season, -35.20±6.58 μg (C)?m-2?h-1 and -0.95±0.10 kg (C)?ha-1 in maize season, -29.96±5.26 μg (C)?m-2?h-1 and -1.74±0.09 kg (C)?ha-1 during the whole experimental period, respectively. The absorption rates and accumulations of CH4 in OM, OMNPK, NPK, RSDNPK, and N treatments were significantly lower than that of CK treatment. The reason may be related to the inhibitions of NH4+ released from ammonium nitrogen and NO3- quickly transformed from NH4+ by purple soil to the activity of methane-oxidizing bacteria.The average CO2 emission rate and accumulation of NPK treatment was 18.43±1.56 mg (C)?m-2?h-1 and 745.94±97.90 kg (C)?ha-1 in wheat season, 79.77±5.13 mg (C)?m-2?h-1 and 2121.53±103.94 kg (C)?ha-1 in maize season, 45.69±4.18 mg (C)?m-2?h-1 and 2867.47±201.65 kg (C)?ha-1 during the whole experimental period, respectively. CO2 emission rates and accumulations in six treatments were significant difference (P<0.01). The corresponding parameters of five fertilized treatments were significantly(P<0.05) higher than that of CK treatment. So, we concluded that the application of fertilizer increased CO2 emission significantly.(2) The soil dissolved organic carbon (DOC) content was the main factor impacting CH4 emission. Except for DOC content, environmental factors impacting CO2 emission included soil temperature, moisture and NO3--N content.Correlation analysis showed that there was no significant correlation between CH4 emission rate and soil temperature, moisture, NH4+-N or NO3--N content, but CH4 emission rate showed a significant positive correlation (R=0.136, P<0.05) with soil DOC content. CO2 emission rate had a significant positive correlation with soil temperature (R=0.665, P<0.01), soil moisture (R=0.116, P<0.05) and DOC (R=0.245, P<0.01), and showed a significant negative correlation with NO3--N content (R=-0.196, P<0.05).(3) Interflow was the main migration pathway of DOC on sloping cropland of purple soil, which accounted for more than 70% to the gross.Surface flow, interflow and total runoff in NPK treatment was 1.28±0.06 m3, 5.84±0.33 m3 and 7.13±0.34 m3. Interflow was the predominant form of runoff on sloping cropland of purple soil, which accounted for 69.1% -88.8% to the total runoff. The annual sediment loss was 628.2±173.9 kg?ha-1. DOC loss in surface flow, interflow and total runoff was 9.35±2.40 kg?ha-1,1.02±0.01 kg?ha-1 and 10.37±2.40 kg?ha-1, respectively.The flux of DOC loss in interflow was generally more than 70% of the gross, namely, interflow was the main migration pathway of DOC on sloping cropland of purple soil.(4) CO2 emission, aqueous and sediment loss was the main pathways of soil organic carbon loss on sloping cropland of purple soil, and CO2 emission was the main pathway of SOC loss.Total SOC loss in NPK treatment was 2888.94 ± 201.81 kg?ha-1, that included 2867.47±201.65 kg?ha-1 in CO2 emission, 10.37±2.40 kg?ha-1 in aqueous form, and 6.42±1.78 kg?ha-1 in sediment form, accounting for 99.41%, 0.41% and 0.13%, respectively. SOC loss through CO2 emission in other five treatments also accounted for more than 98%, which indicated that CO2 emission was the main way of SOC loss.（5）A significant (p<0.05) negative correlation between aqueous and gaseous loss of SOC was found, it may be associated with the content of the active components of soil organic carbon.Correlation analysis showed that CO2 emission was significant negative correlation with organic carbon loss in sediment (R=-0.462, P<0.05) and DOC loss in surface runoff (R=-0.454, P<0.05), which showed that more SOC loss through aqueous way, lower the CO2 would be released. The reason probably was that more organic-rich topsoil taken away by surface runoff, more sediment organic carbon and DOC loss, hence, less organic substrates especially DOC left in soil to supply soil microbes, and lead to weaker microbial activity.
|李涛. 紫色土坡耕地土壤有机碳的损失及其影响因素[D]. 北京. 中国科学院研究生院,2016.|
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