秸秆还田对植烟土壤有机质及团聚体特征的影响

通过2010—2012年的秸秆还田定位试验,利用干、湿筛法研究了不同用量小麦以及玉米秸秆还田后对植烟土壤有机质和团聚体特征的影响。结果表明,随着秸秆还田量的增加,土壤有机质含量、团聚体平均重量直径（MWD）及几何平均直径（GMD）有所增加,但不同秸秆还田对土壤有机质及团聚体特征的效果不同。干筛法测得土壤团聚体的分形维数随两种秸秆还田量增加而减少,湿筛法测得高量玉米秸秆还田（7500 kg/hm²）较低量秸秆还田（1500 kg/hm²）处理的团聚体分形维数显著降低,同时分形维数随着小麦秸秆还田量的增加而降低。等量玉米秸秆较小麦秸秆在提高土壤有机质含量及团聚体特征方面效果较好。土壤有机质与干筛测得MWD及GMD呈极显著正相关,与干筛测得分形维数呈极显著负相关,与湿筛测得GMD及>0.25 mm团聚体含量呈显著性的正相关。总之,通过秸秆还田可增加土壤有机质含量,影响团聚体分布并提高团聚体稳定性。     

秸秆还田对植烟土壤中微生物结构和数量的影响

测定了施加小麦秆糖、玉米秆糠后植烟土壤中细菌、霉菌、施线菌、解磷菌、解钾菌、硝化细菌和反硝化细菌７类菌群的分布及数量;应用生物统计分析法比较了施加不同秸秆对烤烟试验田土壤微生物结构和数量的影响。结果表明,施加７５００ｋｇ／ｈｍ＾２的小麦秆糠、９０００ｋｇ／ｈｍ＾２的玉米秆糠和１５０００ｋｇ／ｈｍ＾２的玉米秆糠都能显著或极显著地增加２０～４０ｃｍ耕作层中微生物的数据。     

秸秆还田和覆盖对烤烟生长发育及品质的影响

为提高烟叶品质,对麦秆还田、稻草还田、稻草覆盖、麦秆覆盖、地膜覆盖、无覆盖进行了比较试验。结果表明:麦秆覆盖的处理上等烟比例、均价最高,地膜覆盖的处理烟叶产量、产值最高。在烟株团棵期之前,土壤温度较低,地膜覆盖保温保湿效果好,烟株生长量增加较快,但从旺长期至初采期麦秆覆盖处理的效果较好,烟株生长量增长较快,稻草覆盖处理次之。麦秆还田处理的烟叶分层落黄较早,且麦秆还田有利于改良土壤、培肥地力。     

Particulate and trace gas emissions from open burning of wheat straw and corn stover in China

Field measurements were conducted to determine particulate emissions and trace gas emissions, including CO2, CO, CH4, NMHCs, NOx, NH3, N2O, and SO2, from open burning of wheat straw and maize stover, two major agricultural residues in China. The headfire ignition technique was adopted, and sampling was performed downwind from the agricultural fire. Particulate matter (PM) and gas emission factors were determined using the carbon mass-balance method. Particle mass size distributions show a prominent accumulation mode peak at 0.26-0.38 microm. Submicron particles dominate PM emissions. Most measured chemical species measured show a similar size distribution as PM. Chemical composition analysis indicates that PM2.5 is largely composed of carbon, K, and Cl. PM2.5 emission factors of wheat straw and maize stover are 7.6 +/- 4.1 g/kg and 11.7 +/- 1.0 g/kg, respectively, It also indicates that 12.1-24.2% of N in biomass is released as nitrogen-based trace gases and 11.0-24.9% of fuel S is emitted as SO2.     

麦草的酶法化学制浆(Ⅰ)不同种类酶液处理对麦草化学制浆性能的影响

对5种不同种类的酶液（包括纤维素酶和半纤维素酶）预处理对麦草化学制浆的影响进行了研究。酶液分别来自于Aspergillus niger An-76、Bacillus pumilus A-30、Pencillium decumbens A-10、Aspergillus L22和Bacillus sp.Y106等5种菌株的发酵液。实验结果一明，与常规烧碱法制浆相比，在蒸煮前用适宜的酶液对麦草进行预处理，可以改善麦草的化学制浆性能，获得具有较低卡伯值和较低筛渣率的纸浆。但粗酶液的性质对制浆性能有较大的影响，其中具有较高木聚糖酶活与纤维素酶活比值的酶液预处理的效果较佳（如An76酶液），它可在保持纸浆得率的基础上降低纸浆的卡伯值（降低20.43%)和筛渣率（从1.39%降低到0.53%)。同时降低蒸煮时有效碱的消耗，因而可在获得相同纸浆硬度的前提下降低蒸煮用碱量。而具有较高纤维素酶活性的粗酶液预处理，在改善麦草制浆性能的同时，也会导致纸浆得率的降低和蒸煮时有效碱的消耗增加。     

秸秆还田下减量施氮对作物产量及养分吸收利用的影响--测试文章

秸秆还田条件下,采用多年田间定位试验研究了N肥减量施用对作物产量、养分吸收利用以及土壤表观N平衡的影响,旨在为关中小麦/玉米一年二熟轮作区合理施用N肥提供依据。结果表明：与常规施N处理(玉米季施氮187.5 kg·hm^-2,小麦季施氮150 kg·hm^-2)相比,2008—2011年三年中,15%减N、30%减N两个处理均未显著降低作物籽粒与秸秆产量;2010—2011年生长季中,15%减N处理降低了作物秸秆N、P、K周年总吸收量,增加了籽粒N、P、K周年总吸收量,其中籽粒P周年总吸收量增加达显著性水平;30%减N处理显著降低了籽粒N和秸秆N、K周年总吸收量,降幅分别为12.9%、41.9%、18.5%,在小麦收获后,30%减N处理的N素盈余量只有11.3 kg·hm^-2,有潜在缺N危险。综合考虑产量、养分吸收利用及土壤表观N平衡,在秸秆还田条件下,15%减N处理的施N量（即玉米季施氮159 kg·hm^-2,小麦季施氮127.5 kg·hm^-2）为本地区最佳N肥用量。     

基于盆栽试验分析3种品牌稻草秸秆腐熟剂对植烟土壤有机碳组分的影响

为了解秸秆腐熟剂在植烟土壤中的施用效果,通过盆钵模拟培养试验,分析了稻草秸秆分别配施化肥和含不同微生物优势菌种的腐熟剂后土壤速效养分、有机碳及其组分和有机碳稳定性评价指标的变化,研究了稻草秸秆配施腐熟剂对植烟土壤有机碳组分的影响。结果表明,相比单施化肥,稻草秸秆配施化肥的土壤颗粒有机碳(POC)、易氧化有机碳(EOC)及溶解有机碳(DOC)含量(质量分数)分别显著升高36.89%、30.77%和75.73%,稻草秸秆配施腐熟剂的土壤碱解氮(AN)、有效磷(AP)、总有机碳(TOC)、POC、EOC及DOC含量(质量分数)分别显著升高了17.42%~28.33%、49.94%~55.68%、10.46%~15.20%、39.32%~74.27%、54.36%~64.62%和84.58%~124.27%;稻草秸秆分别配施化肥和腐熟剂均可显著提高土壤活性有机碳组分的有效率,且可降低有机碳的抗氧化能力,但后者更显著;主成分分析显示,稻草秸秆配施腐熟剂在提高土壤TOC含量的同时,提高了土壤活性有机碳组分的有效率且降低了有机碳抗氧化性能;稻草秸秆分别配施细菌+真菌(XZ)和细菌+真菌+放线菌(XZF)为优势菌种的腐熟剂对植烟土壤有效养分和有机碳组分的影响无明显差异。      

Shifts in comparative advantages for maize, oat and wheat cropping under climate change in Europe

Climate change is anticipated to affect European agriculture, including the risk of emerging or re-emerging feed and food hazards. Indirectly, climate change may influence such hazards (e.g. the occurrence of mycotoxins) due to geographic shifts in the distribution of major cereal cropping systems and the consequences this may have for crop rotations. This paper analyses the impact of climate on cropping shares of maize, oat and wheat on a 50-km square grid across Europe (45-65°N) and provides model-based estimates of the changes in cropping shares in response to changes in temperature and precipitation as projected for the time period around 2040 by two regional climate models (RCM) with a moderate and a strong climate change signal, respectively. The projected cropping shares are based on the output from the two RCMs and on algorithms derived for the relation between meteorological data and observed cropping shares of maize, oat and wheat. The observed cropping shares show a south-to-north gradient, where maize had its maximum at 45-55°N, oat had its maximum at 55-65°N, and wheat was more evenly distributed along the latitudes in Europe. Under the projected climate changes, there was a general increase in maize cropping shares, whereas for oat no areas showed distinct increases. For wheat, the projected changes indicated a tendency towards higher cropping shares in the northern parts and lower cropping shares in the southern parts of the study area. The present modelling approach represents a simplification of factors determining the distribution of cereal crops, and also some uncertainties in the data basis were apparent. A promising way of future model improvement could be through a systematic analysis and inclusion of other variables, such as key soil properties and socio-economic conditions, influencing the comparative advantages of specific crops.     

施用麦秸秆对烤烟产质量的影响

在高肥力的土壤上,研究了小麦秸秆还田对烤烟主要农艺性状及产量、品质和病害发生率的影响。结果表明,施N量2kg/667m2和4kg/667m2时,施秸秆的比不施秸秆的烟叶产量分别增加12 2%和13 9%,差异达显著水平;产值分别增加47 65%和39 25%,差异达极显著水平。在不同施N水平下,施秸秆的比不施秸秆的烟株茎围增加,炭疽病和赤星病发生率降低,烟叶中总糖含量提高,烟碱、总氮及蛋白质含量降低。烟叶的香气质、香气量、杂气、劲头和刺激性等有一定程度改善。     

Development of engineered natural organic sorbents for environmental applications. 1. Materials, approaches, and characterizations

A technology for effecting diagenesis-like transformations in young natural organic matter (NOM) derived from common plant materials is described. Thirteen such materials were processed in liquid-phase water at superheated temperature/pressure conditions. In all cases significant changes in the physical and chemical properties of the raw NOM source materials occurred. Their carbon and nitrogen contents increased, their hydrogen and oxygen contents decreased, their surface areas initially increased dramatically, then sharply decreased, and their bulk densities and equilibrated aqueous phase pH values increased as functions of increasing temperature and pressure. Spectroscopic analyses confirmed marked changes in the molecular structures of the NOMs resulting from superheated water processing; e.g., fractions of alkyl and aromatic carbons increased while oxygen-associated functional organic carbon decreased. These changes in elemental composition and molecular structure indicate that the organic fractions of the raw materials became less polar, increasingly condensed, and more aromatic as a result of the reactions induced by superheated water processing, the changes correlating directly with the temperature/ pressure conditions employed. The results presented confirm that the long-term biogeochemical processes that in nature effect geologically slow advances in the chemical states of organic carbon can be simulated and markedly accelerated by superheated water processing.