有机物料还田对冬小麦农田土壤温室气体排放影响的研究

探讨有机物料还田对冬小麦田温室气体排放特性的影响,对提高经济效应和环境效应有积极意义。本研究应用静态箱-气相色谱法对秸秆还田（J）、秸秆还田+牛粪（JF）和秸秆还田+菌渣（JZ）3种有机物料还田下分别施氮肥243 kg （N）·hm^-2（减氮10%,N1）、216 kg （N）·hm^-2（减氮20%,N2）对冬小麦农田N₂O、CO₂和CH₄的排放通量进行监测,探讨了不同施肥措施对麦田温室气体累积排放量、增温潜势的影响。试验期间同步记录每项农事活动机械燃油量、施肥量和灌溉量,测定产量,地上部生物量,估算农田碳截留。结果表明,冬小麦农田土壤N₂O和CO₂是排放源,是CH₄的吸收汇,氮肥施入、灌溉以及强降水促进了土壤N₂O和CO₂的生成,却弱化了CH₄作为大气吸收汇的特征。牛粪+秸秆（JF）处理N₂O和CO₂排放总量最高,分别为3.5 kg （N₂O-N）·hm^-2和19 689.67 kg （CO₂-C）·hm^-2,但CH₄的吸收值最大,为5.33 kg （CH₄-C）·hm^-2,均显著高于菌渣+秸秆（JZ）和秸秆（J）处理（P<0.05）;各处理N₂O和CO₂的总量随施氮量的增加呈升高趋势,CH₄的总量随施氮量的增加而呈降低趋势。JFN2、JN2和JZN2处理农田综合增温潜势（GWP）均为负值,表明有机物料还田且减氮20%条件下农田生态系统为大气的碳汇,麦季净截留碳1 038~2 024 kg·hm^-2,其他处理GWP值均为正。JZN2处理小麦产量为8 061 kg·hm^-2,显著高于JFN2处理（P<0.05）。综上所述,JZN2处理不仅能够保证小麦产量,且对环境效应最有利,为本区域冬小麦较优的施肥管理模式。     

施氮水平对太行山前平原冬小麦-夏玉米轮作体系土壤温室气体通量的影响

应用静态明箱-气相色谱法对4 个施氮肥水平N0 [0 kg(N)·hm^-2]、N200 [200 kg(N)·hm^-2]、N400 [400kg(N)·hm^-2]、N600 [600 kg(N)·hm^-2]的夏玉米-冬小麦季轮作体系2008~2010 年的土壤温室气体(CH₄、CO₂ 和N₂O)排放通量进行研究, 同时观测5 cm 土层土壤温度并记录降水量。结果表明: 太行山前平原冬小麦-夏玉米轮作农田生态系统为CH₄ 吸收汇, CO₂ 和N₂O 排放源。随着氮肥施入量的增加土壤对CH₄ 的吸收速率降低, 而CO₂ 和N₂O 的排放速率增加。冬小麦季施氮处理土壤对CH₄ 的吸收速率显著低于无氮肥的N0 处理, 而N600处理土壤CO₂ 和N₂O 排放速率显著高于N0 处理(P<0.05)。施肥和灌溉会直接导致土壤CO₂ 和N₂O 的排放通量增加, 同时土壤对CH₄ 的吸收峰值减小。土壤温度升高和降水量增加以及干湿交替加剧均会造成N₂O 和CO₂排放速率增加。同时在持续干燥和低温条件的冬季不施氮处理观测到土壤对N₂O 的吸收现象。N0、N200、N400 和N600 处理土壤CH₄ 年排放总量(kg·hm^-2·a^-1)分别为-1.42、-0.75、-0.82、-0.92(2008~2009 年)和-2.60、-1.47、-1.35、-1.76(2009~2010 年), N0、N200、N400 和N600 处理土壤CO₂ 年排放总量(kg·hm^-2·a^-1)分别为15 597.6、19 345.6、21 455.9、29 012.5(2008~2009 年)和10 317.7、11 474.0、13 983.5、20 639.3(2009~2010年), N0、N200、N400 和N600 处理土壤N₂O 年排放总量(kg·hm^-2·a^-1)分别为1.05、2.16、5.27、6.98(2008~2009年)和1.49、2.31、4.42、5.81(2009~2010 年)。     

耕作措施对温带半干旱地区土壤温室气体(CO2、CH4、N2O)通量的影响

通过设置在甘肃省定西市李家堡镇的不同耕作措施试验, 利用CO₂分析仪、静态箱-气相色谱法对双序列轮作次序下春小麦地、豌豆地生育期内CO₂、CH₄和N₂O通量进行了测定。试验结果表明: 4种耕作措施下春小麦地和豌豆地在生育期内均表现为CO₂源、N₂O源和CH₄汇的功能。传统耕作不覆盖、免耕不覆盖、免耕秸秆覆盖和传统耕作结合秸秆还田下, 春小麦生育期内平均土壤CO₂通量(μmol·m^-2·s^-1)分别为0.203 6、0.221 2、0.241 8、0.224 9, CH₄通量(mg·m^-2·h^-1)分别为-0.041 6、-0.078 0、-0.081 8、-0.053 7, N₂O通量(mg·m^-2·h^-1)分别为0.089 1、0.069 2、0.046 1、0.065 6; 豌豆生育期内平均土壤CO₂通量(μmol·m^-2·s^-1)分别为0.273 6、0.261 6、0.218 1、0.236 0, CH₄通量(mg·m^-2·h^-1)分别为-0.055 0、-0.073 7、-0.066 2、-0.054 5, N₂O通量(mg·m^-2·h^-1)分别为0.123 4、0.084 7、0.080 6、0.035 0。少免耕及小麦秸秆覆盖有利于减少土壤CO₂排放通量, 免耕不覆盖、免耕秸秆覆盖及传统耕作结合秸秆还田均能不同程度地增加CH₄吸收通量、减少N₂O排放通量。综合来看, 免耕不覆盖、免耕秸秆覆盖和传统耕作结合秸秆还田3种保护性耕作措施有助于减少土壤温室气体的排放量。春小麦地CO₂通量随着土壤温度、土壤含水量的逐渐升高而增大; CH₄吸收通量随着土壤含水量的逐渐升高而增大, 而随着土壤温度的逐渐升高而减小。豌豆地CO₂通量的变化与土壤含水量存在极显著正相关关系; 而春小麦地N₂O通量则与平均土壤温度呈显著正相关, 豌豆地则为极显著正相关。     

稻草生物炭对干湿交替稻田CH4和N2O排放的影响

为探究稻草生物炭和灌溉方式对稻田CH₄和N₂O排放的影响,揭示生物炭在干湿交替稻田中的应用潜力,该研究采用大田裂区试验,设置常规淹灌（I_CF）和干湿交替灌溉（I_AWD）2种灌溉方式,不施生物炭（B₀）和施20 t/hm²生物炭（B₂₀）2种施炭水平,连续3 a对稻田CH₄、N₂O排放和水稻产量进行了观测研究。结果表明：与I_CF相比,I_AWD在显著降低CH₄排放（63.03%～78.89%）的同时也促进了N₂O排放（100%～122.67%）。生物炭施加首年对CH₄排放无显著影响,但第2年和第3年分别显著减少CH₄排放21.99%和38.21%;而对N₂O排放3 a均起到抑制作用,降幅达28.26%～33.10%。生物炭3 a平均增加土壤有机碳27.03%。施生物炭第1年水稻略有减产,但第2和第3年表现为正效应。主要是由于初期秸秆生物炭碱性较大,表现出了明显的石灰效应;但随着pH值逐步恢复正常后,生物炭固碳减排和缓释增效特性逐渐显现。尤其在2021年,B₂₀较B₀增产11.02%,显著降低37.50%的全球增温潜势（global warming potential,GWP）和42.86%的温室气体排放强度（greenhouse gas intensity,GHGI）;同时,在B₀条件下,I_AWD较I_CF增加137.21%的N₂O排放,但B₂₀条件下降低I_AWD处理32.52%的N₂O排放,有效抑制I_AWD对N₂O排放增加的负面效应。整体来看,与I_CFB₀处理相比,I_AWDB₂₀处理显著降低CH₄排放,降幅为83.78%,同时降低77.98%的GWP和78.95%的GHGI。该研究为揭示生物炭固碳减排的正效应及其在稻田生态系统中的应用潜力,同时全面探究其对稻田增产、CH₄和N₂O排放的年限影响,为缓解实际稻田生产过程中CH₄和N₂O的排放,实现稻田绿色、高效、可持续生产提供理论依据。     

减量施氮与大豆间作对蔗田土壤温室气体排放的影响

采用静态箱 气相色谱法对常规施氮(N2, 525 kg·hm^-2)y和减量施氮(N1, 300 kg·hm^-2)处理下甘蔗与大豆按行数比1∶1(SB1)和1∶2(SB2)间作、甘蔗单作(MS)、大豆单作(MB)种植模式下蔗田土壤CO₂、N₂O、CH₄排放通量及土地当量比(LER)进行观测和对比分析, 以探讨不同间作模式及施氮水平下甘蔗//大豆间作农田土壤温室气体排放的动态变化规律及对作物产量的影响, 为制定农田温室气体减排措施提供合理的依据。研究结果表明, 减量施氮处理甘蔗//大豆(1∶2)间作模式(SB2-N1)农田土壤CO₂排放总量较甘蔗单作(MS)显著降低35.58%, N₂O累积排放总量较甘蔗单作降低56.36%, CH₄累积排放总量较甘蔗单作升高7.02%; 不同种植模式和施氮处理蔗田土壤均表现为CO₂和N₂O的排放源, CH₄吸收汇, 追施氮肥后土壤对CH₄的吸收速率降低, 但CO₂和N₂O的排放速率增加。MS-N1、SB1-N1、SB2-N1、MS-N2、SB1-N2、SB2-N2和MB处理土壤CO₂年累积排放总量(kg·hm^-2·a^-1)分别为5 096.89、6 422.69、3 283.20、4 103.29、4 475.84、4 775.31和4 780.35, 土壤N₂O年累积排放总量(kg·hm^-2·a^-1)分别为4.61、5.11、2.15、3.13、3.72、5.60和3.11, 土壤CH₄年累积排放总量(kg·hm^-2·a^-1)分别为 13.68、 21.78、 12.72、 5.53、 11.36、 4.77和 9.97。甘蔗//大豆间作系统2009-2012年土地当量比(LER)均大于1, 且减量施氮水平下, 甘蔗//大豆(1∶2)间作模式优势最明显。     

夏季休牧对高寒矮嵩草草甸温室气体排放的影响

以高寒矮嵩草草甸为研究对象，利用密闭箱－气相色谱法，对夏季休牧8a的围栏草地(休牧草地)和全年放牧的草地(放牧草地)的温室气体排放通量、土壤特性和生物量进行了对比研究。结果表明：与放牧草地相比，休牧草地植被盖度较之高41％，单位面积生物量较之高53％。同时，土壤特性也有较大不同；休牧草地的植被－土壤系统CO₂排放通量比放牧草地低20.7％，测定期间两者CO₂排放通量以每天每公顷排放C的质量计分别为30.7和38.7 kg·(hm²·d)^-1；试验期间高寒矮嵩草草甸植被－土壤系统是大气CH₄的弱汇，休牧后草地土壤对CH₄的吸收能力增强，休牧和放牧草地CH₄的平均吸收强度分别为28.1和21.9 g·(hm²·d)^-1；休牧草地土壤N₂O排放通量比放牧草地低，两者排放通量分别为4.5和7.6 g·(hm²·d)^-1。可见，夏季休牧措施降低了草地对大气中温室气体浓度增加的贡献。     

不同耕作条件下豆麦双序列轮作农田土壤温室气体的排放及影响因素研究

为了研究耕作措施对双序列轮作农田土壤温室气体的排放及影响, 采用CO₂分析仪、静态箱 气相色谱法在陇中黄土高原半干旱区对传统耕作不覆盖、免耕不覆盖、免耕秸秆覆盖和传统耕作+秸秆还田4种耕作措施下豆麦双序列轮作农田土壤温室气体(CO₂、N₂O和CH₄)的排放及影响因素进行了连续测定和分析。结果表明: 测定期内4种耕作措施下农田土壤均表现为CO₂源、N₂O源和CH₄净吸收汇; 除传统耕作不覆盖措施, 其他3种耕作措施不同程度地减少了2种轮作序列土壤的N₂O排放通量, 并显著增加了土壤对CH4的吸收。CO₂和N₂O的排放通量分别与地表、地下5 cm处、地下10 cm处的土壤温度呈极显著和显著正相关关系, 相关系数分别为0.92^**和0.89^**、0.95^**和0.91^**、0.77^*和0.62^*; 而CH₄吸收通量与不同地层的温度之间无明显的相关关系; CO₂和CH₄的通量与0~5 cm、5~10 cm的土壤含水量均呈显著正相关关系, 相关系数分别为0.69^*和0.72^*、0.77^*和0.64^*, 而与10~30 cm土壤含水量无明显相关关系; N₂O排放通量与各层次的土壤含水量之间均呈不显著负相关关系。对2种轮作序列各处理下土壤中排放的3种温室气体的增温潜势计算综合得出: 4种耕作措施中, 免耕不覆盖处理可相对减少土壤温室气体的排放量, 进而降低温室效应。     

气候变化下基于DayCent的旱地玉米农田温室气体排放通量模拟

气候变化通过大气CO₂浓度、温度和降雨的改变,直接或间接影响农田温室气体排放,研究未来气候情景下农田温室气体排放对实现农业碳减排具有重要意义。为探究气候变化背景下农田温室气体排放特征,该研究在长期田间定位试验基础上,利用当前大气CO₂浓度与CO₂浓度升高条件下旱作玉米农田温室气体排放通量的田间观测数据,采用“试错法”对DayCent模型进行校验,并利用校验后的模型,根据第六次国际耦合模式比较计划（Coupled Model Intercomparison Project phase 6,CMIP6）气候情景数据,预测未来SSP126与SSP245气候情景下旱地玉米农田温室气体排放通量。结果表明,DayCent模型对不同大气CO₂浓度下N₂O、CH₄和CO₂排放通量的模拟值与观测值高度一致,模拟效率（modeling efficiency,EF）分别为0.58～0.87、0.45～0.65和0.25～0.62,均方根误差（root mean square error,RMSE）分别为0.83～1.33、0.67～0.82和0.58～0.80 g/(hm²·d),决定系数（coefficient of determination,R²）分别为0.80～0.91、0.53～0.80和0.53～0.85。SSP126和SSP245气候情景下,在玉米单作种植模式下旱地农田N₂O和CO₂年排放量均呈现上升趋势,以2001—2020年农田温室气体排放通量为基准,到2060年N₂O年排放量分别增加22.8%和24.9%,CO₂年排放量分别增加6.7%和8.0%;旱地农田CH₄年吸收量呈下降趋势,两个气候情景下分别减少13.6%和13.4%。未来气候情景下旱地农田仍是温室气体排放源,优化氮肥管理和农田耕作措施对实现温室气体减排具有重要意义,模拟结果可以为制定农业适应气候变化对策提供基础数据支持。     

华北平原氮肥周年深施对冬小麦-夏玉米轮作体系土壤氨挥发的影响

氮肥深施能有效减少土壤氨挥发，然而目前国内外关于小麦-玉米轮作体系氮肥深施缺乏周年系统性研究。本试验于2018年10月—2019年10月在中国科学院栾城农业生态系统试验站小麦-玉米轮作农田进行，利用动态箱法研究不同深施模式氨挥发损失率、氨挥发特征，旨在探讨冬小麦-夏玉米轮作体系下土壤氨排放对氮肥深施的响应，为减少农业源氨排放和优化农田施肥提供理论依据。试验设置5个处理：不施肥（CK）、常规肥料表施（T₁）、缓释肥表施（T₂）、缓释肥基追肥分层深施（T₃）、缓释肥一次性分层深施（T₄）。结果表明：氨挥发主要发生在玉米追肥季，占全年氨挥发量的84.84%；T₁、T₂、T₃和T₄处理的周年氨挥发累积量分别为22.75 kg·hm^-2、6.17 kg·hm^-2、2.25 kg·hm^-2和0.55 kg·hm^-2，分别占总施肥量的4.86%、1.32%、0.48%和0.13%。与常规肥料表施（T₁）相比，缓释肥处理（T₂、T₃和T₄）分别降低72.88%、90.11%和97.32%的氨挥发损失；一次性深施处理（T₄）能避开土壤氨高挥发期，周年氨挥发累积量与不施肥处理（0.43 kg·hm^-2）没有显著差异，且显著低于表施处理。CK、T₁、T₂、T₃和T₄全年产量分别为8.31 t·hm^-2、13.20 t·hm^-2、12.66 t·hm^-2、14.42 t·hm^-2和14.22 t·hm^-2；与常规肥料表施（T₁）相比，缓释肥深施（T₃和T₄）均可提高作物产量，分别增产9.25%和7.75%。而缓释肥表施（T₂）产量略有降低。综合考虑土壤氨排放和作物产量，缓释肥表施（T₂）可以显著降低土壤氨挥发，但是作物产量不稳定；而氮肥深施（T₃、T₄）能在保证作物高产的基础上显著降低土壤氨排放，是一种高效、简便、环境友好的施肥方式。     

华北平原小麦-玉米农田生态系统服务评价

本研究于2006 年和2007 年在中国科学院栾城农业生态系统试验站田间试验基础上, 评价了华北平原小麦-玉米农田的初级产品生产、气体调节、土壤有机质累积、水调节和氮素转化等5 项生态系统服务。研究表明, 华北平原小麦-玉米农田初级产品量包括籽粒产量5.04~5.71 t·hm^-2·a^-1(小麦)和6.69~8.24t·hm^-2·a^-1(玉米), 秸秆量8.58~9.72 t·hm^-2·a^-1(小麦)和6.97~8.58 t·hm^-2·a^-1 (玉米); 农田气体调节包括释放O₂ 24.99~28.64 t·hm^-2·a^-1, 固定CO₂ 34.23~39.22 t·hm^-2·a^-1, 排放N₂O 0.72~1.13 kg·hm^-2·a^-1, 吸收CH₄ 3.39~5.70 kg·hm^-2·a^-1; 农田耕层土壤有机质累积量为1.13~2.39 t·hm^-2·a^-1; 水资源消耗量为2 890~3 830 m³·hm^-2·a^-1; 农田土壤氮素几乎都处于亏缺状态, 变化范围为-107.73~5.33 kg(N)·hm^-2·a^-1, 不施氮肥农田亏缺较多。综合评价发现, 小麦-玉米农田提供生态服务的经济价值为5.48~6.25 万元·hm^-2·a^-1, 是粮食生产价值的3 倍左右。氮肥施用对农田生态系统服务及其产生福利的影响较为复杂, 这主要是由于施加氮肥明显增加了氮素转化功能导致的经济损失, 而同时可能会增加初级产品生产、气体调节中作物固定CO₂ 和释放O₂ 功能的经济价值。尽管目前有关生态系统服务评价研究主要关注生态系统产生的正效应, 但仍有必要对农田产生的负效应做出评价, 以便客观看待农田生态系统价值, 正确认识农田生态系统对人类福利的影响。     

生物炭和腐殖酸施用对稻麦轮作系统CH4和N2O综合温室效应的影响

生物炭和腐殖酸对土壤C、N循环和作物产量均具有深刻影响。该试验以稻麦轮作系统为研究对象,探究生物炭和腐殖酸在经过1 a陈化后对土壤肥力、作物产量和温室气体排放的持续影响。设置了6个处理：B0F0(对照,不添加生物炭和腐殖酸);B0F1(不添加生物炭,腐殖酸添加量为0.6 t/hm²);B0F2(不添加生物炭,腐殖酸添加量为1.2 t/hm²);B1F0(生物炭添加量为20 t/hm²,不添加腐殖酸);B1F1(生物炭添加量为20 t/hm²,腐殖酸添加量为0.6 t/hm²);B1F2(生物炭添加量为20 t/hm²,腐殖酸添加量为1.2 t/hm²)。结果表明：1)试验期内,与B0F0相比,生物炭显著增加了稻麦两季土壤有机碳含量;腐殖酸增加了稻季土壤有机碳含量,对麦季土壤有机碳含量无显著影响;单独施用生物炭或腐殖酸对水稻和小麦产量均没有显著影响,生物炭和腐殖酸混施处理显著提高了小麦产量,增幅为1.0%～5.0%,对水稻产量没有显著影...     

Nitrous oxide emission,global warming potential,and denitrifier abundances as affected by long-term fertilization on Mollisols of Northeastern China

ABSTRACT

A long-term field experiment was performed to assess the effects of fertilization regimes on greenhouse gas emissions, soil properties, soil denitrifies, and maize (Zea mays) grain yield on Mollisols of Northeastern China. Chemical nitrogen (N), phosphorus (P), and potassium (K) fertilizers plus pig manure (MNPK) treatment significantly increased soil N₂O emissions by 29.9–226.4% and global warming potential (GWP) by 29.8–230.7% compared to unfertilized control (CK), chemical N fertilizer only (N), chemical N, P, and K fertilizers (NPK) and chemical N, P, and K fertilizers plus corn straw (SNPK) treatments. However, the MNPK treatment yielded similar greenhouse gas intensity (GHGI) as compared with other treatments, mainly due to higher maize grain yield. There were also higher gene copy numbers of nirK, nirS, and nosZ in topsoil (0–20 cm depth) under MNPK treatment. Automatic linear modeling analysis indicated that main factors influencing soil N₂O emissions were soil organic carbon (SOC), NO₃^? content, and nirK gene abundance. Although the application of chemical fertilizers plus organic manure increases N₂O emissions due to higher N and C availability and nirK gene activity in the soil, this is still a promising fertilizer management due to its notable enhancement of maize grain yield and SOC content.     

Contrasting effects of wheat straw and its biochar on greenhouse gas emissions and enzyme activities in a Chernozemic soil

Biochar produced from plant biomass through pyrolysis has been shown to be much more resistant to biodegradation in the soil as compared with the raw biomass, such as cereal straw that is routinely shredded and discharged on to farm fields in large amounts. Biochar application to soil has also been reported to decrease greenhouse gas (GHG) emissions, although the mechanisms are not fully understood. In this study, the emissions of three main GHGs (CO₂, CH₄, and N₂O) and enzyme activities (urease, β-glycosidase, and dehydrogenase) were measured during a 100-day laboratory incubation of a Chernozemic soil amended with either straw or its biochar at rates of 0.67 and 1.68 % (based on the amount of C added) for the low and high rates, respectively. The biochar application dramatically reduced N₂O emissions, but CO₂ or CH₄ emissions were not different, as compared with the un-amended soil. At the same C equivalent application rate, CO₂ and N₂O emission rates were greater while CH₄ emission rates were lower in straw than in biochar application treatments. The activities of both the dehydrogenase and β-glycosidase significantly declined while that of urease significantly increased with the biochar as compared with the straw treatment. We conclude that pyrolysis of cereal straw prior to land application would significantly reduce CO₂ and N₂O emissions, in association with changed enzyme activities, while increasing the soil C pool through the addition of stable C in the form of biochar.     

Short-term effects of raw rice straw and its derived biochar on greenhouse gas emission in five typical soils in China

Abstract

A short-term study was conducted to investigate the greenhouse gas emissions in five typical soils under two crop residue management practices: raw rice straw (Oryza sativa L., cv) and its derived biochar application. Rice straw and its derived biochar (two biochars, produced at 350 and 500°C and referred to as BC350 and BC500, respectively) were incubated with the soils at a 5% (weight/weight) rate and under 70% water holding capacity for 28 d. Incorporation of BC500 into soils reduced carbon dioxide (CO₂) and nitrous oxide (N₂O) emission in all five soils by 4?40% and 62?98%, respectively, compared to the untreated soils, whereas methane (CH₄) emission was elevated by up to about 2 times. Contrary to the biochars, direct return of the straw to soil reduced CH₄ emission by 22?69%, whereas CO₂ increased by 4 to 34 times. For N₂O emission, return of rice straw to soil reduced it by over 80% in two soils, while it increased by up to 14 times in other three soils. When all three greenhouse gases were normalized on the CO₂ basis, the global warming potential in all treatments followed the order of straw > BC350 > control > BC500 in all five soils. The results indicated that turning rice straw into biochar followed by its incorporation into soil was an effective measure for reducing soil greenhouse gas emission, and the effectiveness increased with increasing biochar production temperature, whereas direct return of straw to soil enhanced soil greenhouse gas emissions.     

秸秆直接还田及炭化还田对土壤酸度和交换性能的影响

【目的】 本研究旨在通过连续4年田间微区定位试验,比较等氮磷钾养分条件下秸秆炭化还田与等量秸秆直接还田对土壤酸度及交换性能的影响,以期为土壤酸化改良及秸秆、生物炭资源合理利用提供理论依据。 【方法】 试验以沈阳农业大学植物营养与肥料研究所玉米渗滤池微区定位试验为基础,共设6个处理,分别为不施肥 (CK)、氮磷钾配施 (NPK)、单施生物炭 (C)、生物炭+NPK(CNPK)、单施秸秆 (S)、秸秆+NPK(SNPK)。其中NPK、CNPK和SNPK处理养分投入总量相等,均为N 225 kg/hm2、P₂O₅ 112.5 kg/hm2和K₂O 112.5 kg/hm2,S处理秸秆施用量为4500 kg/hm2,单施生物炭处理生物炭施用量为1500 kg/hm2。应用化学分析法对土壤活性酸、交换性酸、阳离子交换量及交换性盐基离子进行分析和测定。 【结果】 经过连续4年的不同施肥处理,施用生物炭及秸秆均显著提高了土壤pH,降低了土壤交换性酸总量和交换性铝含量,但各处理间交换性H+含量差异不显著。相较于试验前土壤 (pH 6.05),单施生物炭和单施秸秆处理分别使土壤pH提高了0.55和0.45个单位。在等氮磷钾养分条件下,CNPK和SNPK处理较试验前分别使土壤pH提高了0.31和0.13个单位,且CNPK处理显著高于SNPK,但二者之间对土壤交换性酸含量的影响无显著差异。同时各处理交换性盐基离子总量均显著高于CK,单独施用生物炭对提高土壤盐基总量、交换性Ca2+和交换性Mg2+的效果显著优于单独施用秸秆。在等秸秆量与等氮磷钾养分条件下,秸秆炭化还田及秸秆直接还田较不施肥对照分别使交换性盐基总量提高了17.6%和15.1%,且秸秆炭化还田对提高土壤有效阳离子交换量的效果显著优于秸秆直接还田。与CK处理相比,C、CNPK、S和SNPK处理分别使土壤阳离子交换量提高了1.68、2.52、1.53、2.30 cmol/kg,其中以CNPK处理效果最佳。 【结论】 在等秸秆量和等氮磷钾养分条件下,施用生物炭和秸秆能有效降低土壤酸度和交换性酸中交换性铝含量,提高土壤盐基离子含量及交换性能,且秸秆炭化还田的效果更为明显。      

Effects of biochar amendment on greenhouse gas emissions,net ecosystem carbon budget and properties of an acidic soil under intensive vegetable production

Biochar addition to soils has been frequently proposed as a means to increase soil fertility and carbon (C) sequestration. However, the effect of biochar addition on greenhouse gas emissions from intensively managed soils under vegetable production at the field scale is poorly understood. The effects of wheat straw biochar amendment with mineral fertilizer or an enhanced‐efficiency fertilizer (mixture of urea and nitrapyrin) on N₂O efflux and the net ecosystem C budget were investigated for an acidic soil in southeast China over a 1‐yr period. Biochar addition did not affect the annual N₂O emissions (26–28 kg N/ha), but reduced seasonal N₂O emissions during the cold period. Biochar increased soil organic C and CO₂ efflux on average by 61 and 19%, respectively. Biochar addition greatly increased C gain in the acidic soil (average 11.1 Mg C/ha) compared with treatments without biochar addition (average ?2.2 Mg C/ha). Biochar amendment did not increase yield‐scaled N₂O emissions after application of mineral fertilizer, but it decreased yield‐scaled N₂O by 15% after nitrapyrin addition. Our results suggest that biochar amendment of acidic soil under intensive vegetable cultivation contributes to soil C sequestration, but has only small effects on both plant growth and greenhouse gas emissions.     

长期施肥下黑土玉米田土壤温室气体的排放特征

研究不同施肥措施下东北黑土区玉米农田温室气体(CO_2、N_2O和CH_4)的排放量及其增温潜势,将为制定农业温室气体减排措施提供理论依据。本研究以国家(公主岭)黑土长期定位试验为平台,采用静态箱-气相色谱法对不同施肥措施下玉米农田土壤温室气体排放通量进行了监测,并分析了不同施肥处理间玉米田的综合温室效应差异。结果表明:各施肥处理土壤温室气体CO_2和N_2O的排放高峰均出现在玉米拔节期。农家肥和化肥配施(M_2NPK)处理土壤CO_2、N_2O排放通量和CH_4吸收量均显著高于施化肥处理(P0.05);施用化肥处理土壤CO_2、N_2O排放通量高于不施肥处理;撂荒区土壤CO_2排放通量最高,而土壤N_2O排放通量显著低于施肥处理;等施氮量条件下,化肥(NPK)处理土壤N_2O排放通量明显高于秸秆还田(SNPK)处理,而土壤CH4净吸收量结果则截然相反。从土壤综合温室效应和温室气体强度可分析出,与不施肥(CK)比较,偏施化肥N和NPK处理的综合温室效应(GWP)分别增加了142%和32%,SNPK综合温室效应降低了38%;尤其是有机无机配施(M_2NPK)处理的综合温室效应为负值,为净碳汇。平衡施肥NPK和有机无机肥配施(SNPK和M_2NPK)温室气体排放强度(GHGI)较弱,显著低于不施肥(CK)和偏施化肥(N)处理,其中M2NPK为-222 kg CO_2-eq·t~(-1)。因此,为同步实现较高的玉米产量和较低的温室气体排放强度,有机无机肥配施是东北黑土区较为理想的土壤培肥方式。     

Reduced mineral fertilization coupled with straw return in field mesocosm vegetable cultivation helps to coordinate greenhouse gas emissions and vegetable production

Purpose

The partial substitution of mineral fertilizers with straw in agricultural soils could help to control soil acidification, reduce the risk of eutrophication from agricultural runoff, and increase the utilization efficiency of straw. However, the effects of such coupled practices on greenhouse gas (GHG) emissions and production yields in vegetable fields are not clear. Therefore, the objectives of this study were to (1) understand methane (CH₄) and nitrous oxide (N₂O) emissions in response to the same amounts of straw return with varied amounts of mineral fertilizers, and (2) to identify a solution which could better coordinate GHG emissions, vegetable production yield, and the utilization of agricultural straw following disposal.

Materials and methods

We conducted four-season (lettuce-cabbage-chili-lettuce) vegetable cultivation for 1 year using a control treatment (CT), mineral fertilization only (F), and four mineral fertilization treatments plus maize straw (FS, 0.7FS, 0.6FS, and 0.5FS). We then examined seasonal changes of CH₄ and N₂O fluxes, CH₄ and N₂O cumulative emissions, soil organic carbon (SOC), nitrate nitrogen (NO₃^?-N) and ammonium nitrogen (NH₄⁺-N) content, vegetable yields, global warming potential (GWP), greenhouse gas intensity (GHGI), and N₂O emission factors (EF).

Results and discussion

Compared to the F treatment, the application of maize straw increased the N₂O flux significantly in the FS, 0.7FS, 0.6FS, and 0.5FS treatments. In treatments with added straw, the reduced application of mineral fertilizer led to a reduction in the cumulative N₂O emission; this was due to the reduced content of NO₃^?-N content. The lowest CH₄ flux and cumulative CH₄ emission were observed in the 0.7FS treatment; this may be due to a form of competitive oxidation between CH₄ and NH₄⁺-N from urea. Furthermore, the application of maize straw in combination with a full dose of mineral fertilizers led to high GWP and GHGI values, which showed increases of 88.7% and 78.8%, respectively, in comparison with the F treatment. When taking SOC storage variations into account, which were caused by straw decomposition during cultivation, we identified a negative net GHGI (NGHGI) value (??0.0448 kg CO₂-eq kg^?1 yield) in the 0.7FS treatment. This indicated that the NGHGI had decreased by 116.2% relative to the F treatment when based on similar vegetable yields.

Conclusions

Straw combined with 70% mineral fertilizer led to better GHG emissions and vegetable yield when taking into account the carbon sequestration and decomposition caused by the addition of straw.

     

Soil greenhouse gas emissions,organic carbon and crop yield following pinewood biochar and biochar–manure applications at eroded and depositional landscape positions: A field trial in South Dakota,USA

Soil amendments can help reduce greenhouse gas (GHG) emissions and increase soil organic carbon (SOC) and crop yield. However, most biochar studies have been conducted on single soil type under controlled conditions. To address this limitation, the aim of this research was to investigate how field biochar and manure applications affect soil quality, plant productivity, and GHG emissions at eroded (sandy loam) and depositional (clay loam) positions in a climate transition zone (udic to ustic and mesic to frigid temperature). A field study was established in 2013 in South Dakota, USA, under a corn–soya bean rotation. Soil treatments included biochar, manure, a manure and biochar mixture, and a control (untreated soil). Soil properties (pH, electrical conductivity (EC), SOC, available nitrogen, available phosphorus and available potassium) were measured in 2017. Plant productivity parameters in 2016 and 2017 and GHG fluxes were measured during the 2016 and 2017 growing seasons. Compared with the control, SOC increased under all treatments at the eroded position (biochar 26%, manure 24%, and manure–biochar mixture 15%) and increased under biochar (25%) and the manure–biochar mixture (25%) at the depositional position. Plant parameters were similar under all treatments at both positions. Area-scaled CO₂ fluxes were lower in soils treated with biochar compared with the control at the eroded landscape position but not at the depositional landscape position. Area-scaled N₂O fluxes were lower in soils treated with biochar at both positions. Furthermore, the biochar–manure mixture treatment emitted lower area-scaled N₂O fluxes compared with manure alone at both positions. This study suggests that for eroded and depositional landscape positions, biochar can improve soil organic carbon and the effects of the biochar and biochar–manure mixture on GHG emissions vary based on the soil texture.     

秸秆还田与施氮对黑土区春玉米田产量、 温室气体排放及土壤酶活性的影响

探讨秸秆还田与施氮对高纬度黑土区春玉米产量与温室气体排放特性的影响,对促进粮食增产和降低环境代价具有重要意义。本研究通过位于黑土区的大田定位试验,利用静态箱-气相色谱计数方法,在秸秆还田与不还田和3个氮素用量(纯N:120 kg·hm~(-2),240 kg·hm~(-2)和300 kg·hm~(-2))条件下,研究了春玉米不同生育时期农田土壤CO2、N2O和CH4综合温室效应与排放强度,以及土壤过氧化氢酶和脲酶活性的变化。结果表明:无秸秆还田时,高氮用量处理春玉米产量最高;秸秆还田后,中等氮用量处理(240 kg·hm~(-2))春玉米产量最高,且与无秸秆还田的高氮处理间无显著差异。无秸秆还田时,随施氮量增加,CO2、N2O和CH4排放量均显著提高,综合温室效应和土壤温室气体排放量与强度显著增加(P0.05);增施氮肥配合秸秆还田,增加了CO2和N2O的排放量,而土壤CH4的碳汇功能增强,温室气体排放量与强度未显著提高(P0.05)。无秸秆还田,增施氮肥降低了土壤过氧化氢酶活性但提高了土壤脲酶活性;而秸秆还田使得增施氮肥引起的土壤过氧化氢酶活性降低的幅度加大但土壤脲酶活性提高的幅度变小。因此,秸秆还田后配合中等用量氮处理(240 kg·hm~(-2))玉米产量最高,且能够抑制单纯增施氮肥对综合温室效应和土壤温室气体排放强度的促进作用,推荐在生产中参考使用。