Modelling impacts of alternative farming management practices on greenhouse gas emissions from a winter wheat–maize rotation system in China

Agricultural production plays an important role in affecting atmospheric greenhouse gas concentrations. Field measurements were conducted in Quzhou County, Hebei Province in the North China Plains to quantify carbon dioxide (CO₂) and nitrous oxide (N₂O) emissions from a winter wheat–maize rotation field, a common cropping system across the Chinese agricultural regions. The observed flux data in conjunction with the local climate, soil and management information were utilized to test a process-based model, Denitrification–Decomposition or DNDC, for its applicability for the cropping system. The validated DNDC was then used for predicting impacts of three management alternatives (i.e., no-till, increased crop residue incorporation and reduced fertilizer application rate) on CO₂ and N₂O emissions from the target field. Results from the simulations indicated that (1) CO₂ emissions were significantly affected by temperature, initial SOC, tillage method, and quantity and quality of the organic matter added in the soils; (2) increases in temperature, initial SOC, total fertilizer N input, and manure amendment substantially increased N₂O emissions; and (3) temperature, initial SOC, tillage, and quantity and quality of the organic matter added in the soil all had significant effects on global warming. Finally, five 50-year scenarios were simulated with DNDC to predict their long-term impacts on crop yield, soil C dynamics, nitrate leaching losses, and N₂O emissions. The modelled results suggested that implementation of manure amendment or crop residue incorporation instead of increased fertilizer application rates would more efficiently mitigate GHG emissions from the tested agro-ecosystem. The multi-impacts provided a sound basis for comprehensive assessments on the management alternatives.     

埋地含蜡原油管道凝管损失计算模型研究

分析了凝管处理过程中可能发生的各项费用,根据它们的特点和性质将其划分为管道清理费、临时土地占用赔偿、管道停输损失、环境污染赔偿和其他费用等5类.建立了凝管损失计算模型,同时给出了5类费用的计算公式.针对环境污染赔偿计算缺乏依据标准的问题,提出了采用土地永久征地价格作为环境污染赔偿标准参与计算.并将该模型用于国内某管道发生全线凝管事故的损失计算,对计算结果进行了分析.结果显示,模型计算得到损失大小和损失组成特点符合实际,表明所建模型可以用于凝管损失计算,并有利于含蜡原油管道风险评价的开展.     

不同氮水平下间作对玉米土壤硝化势和氨氧化微生物数量的影响

利用荧光定量PCR(real-time quantitative PCR,Q-PCR)技术,结合氨氧化细菌(ammonia oxidizing bacteria,AOB)和氨氧化古菌(ammonia oxidizing archaea,AOA)丰度和土壤理化性质的测定,探索了不同氮水平下间作对玉米土壤硝化势(PNF)的影响.试验设置玉米单作和与马铃薯间作两个种植模式,4个施氮水平(不施氮N0、1/2常规施氮N1、常规施氮N2和3/2常规施氮N3)的随机区组试验.结果表明,从不施氮到常规施氮,土壤硝化势和AOA、AOB数量均随施氮量增加而逐渐增加,而高氮(N3)时与N2没有显著差异;间作对土壤硝化势、AOA与AOB数量的影响与施氮量和作物生育期有关,低氮投入(N1)间作有利于增加土壤氨氧化微生物数量和硝化作用.施肥是硝化势增加的主要驱动因子,相关性分析结果表明,土壤含水量是影响PNF的主要环境因子;PNF与土壤中AOA、AOB amoA基因丰度成显著的正相关.尽管玉米马铃薯间作降低了土壤中AOA、AOB amoA基因丰度,却使得间作土壤中AOB占据氨氧化微生物数量上的优势.以上结果表明,施氮和间作均影响了土壤硝化作用和氨氧化微生物AOA和AOB数量的变化,这些变化会影响土壤环境质量.     

晋南两熟半干旱区“粮药”(半夏)农田生态抗旱耕作模式效益研究

采用大田试验,设计冬小麦(Triticum aestivum Linn.)在春季起身后套作半夏[Pinellia ternata(Thunb.)Breit.](小麦/半夏)、冬油菜(Brassica campestris L.)收获后复播半夏[Pinellia ternata(Thunb.)Breit.](油菜-半夏)和春玉米(Zea mays L.)与半夏[Pinellia ternata(Thunb.)Breit.]间作(玉米+半夏)3种耕作模式,探讨晋南两熟半干旱区适宜半夏的粮药耕作模式。结果表明:与油菜-半夏、玉米+半夏耕作模式相比,小麦/半夏耕作模式经济产量最高,生态效益最好;不同半夏品种中,西河半夏(原产地温度相对最低)产量最高,新绛半夏(原产地温度相对较高)产量最低。表明半夏适宜于从低温地区引种到高温地区栽培,可提高产量。与商洛半夏和新绛半夏相比,西河半夏分别增产19.1%和41.9%;小麦/半夏耕作模式为最佳粮药耕作模式,其半夏产量与油菜-半夏和玉米+半夏耕作模式相比,分别增产53.4%和70.8%。     

生长调节剂对春玉米氮素代谢关键酶活性的影响

采用大田小区试验,通过新型植物生长调节剂处理春玉米,研究了生长调节剂对玉米氮素代谢关键酶活性的影响,结果表明,喷施不同配方的生长调节剂能明显提高春玉米氮代谢过程中关键酶的活性。在生长调节剂PGR2处理下,玉米功能叶片中硝酸还原酶(NR)活性比对照提高了109.3%～138.3%,其它处理下硝酸还原酶活性也有不同程度的提高;无论在玉米功能叶片还是籽粒中,谷氨酰胺合成酶(GS)和谷氨酰胺转化酶活性在测定的各时期均高于对照;功能叶片中蛋白水解酶活性也均高于对照。在所有处理中,以PGR2处理效果最佳。     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

mCry1Ac基因在抗虫转基因玉米Bt799中的表达特征

采用双抗夹心酶联免疫法(ELISA)定量检测转mCry1 Ac基因抗虫玉米Bt799在不同生育期不同植株部位的mCry1Ac蛋白含量。结果显示:mCry1 Ac基因在整个生育期玉米叶、茎、根和种子中均能表达,mCry1Ac蛋白含量为(0.82±0.10)~(15.83±1.77)μg·g-1;随着生育期和植株部位的不同,mCry1Ac蛋白含量呈现明显的时空动态变化,其中,叶、茎和根中mCry1Ac蛋白含量随转基因玉米生育期的推移均呈增加趋势,并均在完熟期达最高;在除苗期外的其他各生育期叶中mCry1Ac蛋白含量均显著高于其他植株部位,而在完熟期种子中mCry1Ac蛋白含量在各植株部位中最低,为(2.86±1.71)μg·g-1。     

改性秸秆吸附微生物对土壤中石油烃降解及演化特征的影响

以甲基丙烯酸丁酯-苯乙烯改性玉米秸秆（BMGS）为载体吸附微生物对油污土壤进行了模拟降解实验,研究BMGS作为菌剂载体对油污土壤的降解效果,同时利用GC-MS指纹图谱深入分析TPH（total petroleum hydrocarbon）的重要组分——正构烷烃的降解演化规律和特性。结果表明：BMGS具有较高吸油能力（10.3 g·g-1）,大于原秸秆（RMS）5.7 g·g-1;在3%含油量的油污土壤中,加入用BMGS吸附的菌剂的降解半衰期（14.8 d）均短于空白与用原秸秆（RMS）吸附的半衰期（36.1 d和33.0 d）。降解演化特性表明,2种秸秆RMS与BMGS材料对正构烷烃降解的促进作用依次提高,主峰碳数均出现前移,且BMGS的效果更为明显。加入BMGS后有利于菌剂降解较难降解的偶碳数正构烷烃和类异戊二烯烷烃,并且在降解前、后期,对低、高碳数正构烷烃的降解优势完成增效作用,高碳数正构烷烃平均降解率达到91.25%,较好地解释BMGS吸附菌剂后可以缩短降解TPH半衰期及提高降解率的原因。     

近50a华北平原冬小麦-夏玉米耗水规律研究

为明确华北平原主导作物冬小麦-夏玉米耗水量的变化趋势,为水资源配置提供科学依据,论文搜集文献资料,结合中国科学院禹城综合试验站长期观测数据,采用Mann-Kendall检验法分析了华北平原近50 a冬小麦和夏玉米的耗水量变化趋势,阐明其耗水特性和作物水分利用效率变化,最后通过对蒸发能力和气象要素的变化趋势分析明确了冬小麦-夏玉米耗水量变化的主导原因。研究表明:①近50 a华北平原主导作物冬小麦-夏玉米耗水量呈下降趋势,冬小麦耗水量从501.2 mm降低到456.3 mm,夏玉米耗水量大体变化在300~400 mm,平均为350 mm左右;②冬小麦和夏玉米水分利用效率大幅度提高,冬小麦水分利用效率由3.31 kg/(hm²·mm)增至15.91 kg/(hm²·mm);夏玉米水分利用效率从3.72 kg/(hm²·mm)提高到23.36 kg/(hm²·mm);③拔节-乳熟期是冬小麦耗水强度和耗水量最大的一个时期,华北平原需要通过多次灌溉满足作物水分供需平衡,拔节-灌浆期是夏玉米耗水强度和耗水模系数都比较高的时期,适逢华北地区雨热同期,一般不需要进行补充灌溉;④大气相对湿度增加和日照时数减少是蒸发能力减弱的主因,进而导致作物耗水量呈现下降趋势。     

3种腐熟剂促进玉米秸秆快速腐解特征

为筛选出适宜东北寒冷区快速腐解秸秆的腐熟剂,通过网袋腐解试验明确施入3种秸秆腐熟剂对玉米秸秆生物量及养分释放的影响。结果显示：经过100 d的腐解,玉米秸秆生物量失重率随着时间的延长逐渐增加,玉米秸秆失重率为57.1%-64.1%,其中以施用3号秸秆腐熟剂的玉米秸秆生物量失重率最高,为64.1%。施入不同秸秆腐熟剂后玉米秸秆氮、磷、钾释放率分别为35.1%-57.2%、44.2%-59.6%、77.4%-89.7%,其中以3号腐熟剂的秸秆磷、钾素释放率最高。各处理有机碳矿化率呈相同的趋势,均随时间的延长逐渐增加,取样末期有机碳矿化率在65.3%-69.1%之间,且各处理间差异不明显。综上,以3号秸秆腐熟剂腐解秸秆的效果最好。