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Effects of different long-term crop straw management practices on ammonia volatilization from subtropical calcareous agricultural soil 
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下载免费PDF全文 《大气和海洋科学快报》2020,(3)
长期秸秆还田或秸秆焚烧会显著影响土壤肥力及土壤氮素循环,但该措施对土壤氨挥发的影响仍尚不明确。本研究利用秸秆还田长期定位试验小区,研究了无秸秆配施(CK),配施100%或50%秸秆(SI1, SI2)和配施50%秸秆焚烧(SI2B)对土壤氨挥发的影响。结果表明:氨挥发在小麦季持续38天,而玉米季持续7–10天。秸秆还田显著影响混施基肥期的土壤氨挥发而非表施追肥期。与CK相比, SI1和SI2分别降低了35.1%和16.1%的年累积氨排放,可能因为秸秆的高C/N比及较高的微生物活性促进了无机氮的固定降低土壤NH4+的浓度。SI2B比SI2增加了29.9%的氨排放。因此,长期合理的秸秆还田可为石灰性旱地土壤氨挥发减排提供选择和依据。 相似文献
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种植不同作物对农田N2O和CH4排放的影响及其驱动因子 总被引：3，自引：0，他引：3
以种植玉米(Zea mays)、大豆(Glycine max)和水稻(Oryza sativa)的农田生态系统为研究对象,于2003年6~10月系统观测了N2O和CH4的排放、土壤温度和湿度以及相关的生物学因子。玉米和水稻分别施化肥氮300 kg.hm-2,大豆未施氮肥。研究结果表明,作物类型对农田N2O和CH4排放具有显著的影响。土壤-玉米系统、土壤-大豆系统和土壤-水稻系统的N2O季节性平均排放通量分别为620.5±57.6、338.0±7.5和238.8±13.6μg.m-2.h-1(N2O)。种植作物促进了农田生态系统的N2O排放,玉米地土壤和裸地土壤的N2O平均排放通量分别为364.2±11.7和163.7±10.5μg.m-2.h-1(N2O)。土壤-玉米系统、土壤-水稻系统、玉米地土壤和裸地土壤N2O排放受土壤温度的影响,与土壤湿度无显著统计相关,但受土壤温度和水分的综合影响。土壤-大豆系统N2O排放随作物绿叶干重的增加而指数增加,与土壤温度和水分条件无统计相关,由大豆作物自身氮代谢所产生的N2O-N季节总量约为6.2 kg.hm-2(N)。土壤-水稻系统CH4平均排放通量为1.7±0.1 mg.m-2.h-1(CH4),烤田抑制了稻田CH4的排放。烤田前影响稻田CH4排放的主要因素是水稻生物量,烤田后的浅水灌溉及湿润灌溉阶段的CH4排放与土壤温度和水稻生物量无关。本研究未观测到旱作农田有吸收CH4的现象。 相似文献
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《沙漠与绿洲气象(新疆气象)》1990,(10)
为改进750g探空气球质量,提高施放高度,8月下旬广州第十一橡胶厂王学英(副厂长)、吕新平(工程师)两人来疆,在乌鲁木齐市气象处试放新配方750g气球,并有新的突破,取得可喜成绩. 从8月24日07时至9月2日19时,共施 相似文献
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获得矩阵乘积的特征值与奇异值的不等式。(1 )设 A、B为非负定 Hermite阵 ,1≤ i1 <… 相似文献
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一、引 言 设因变量Y和自变量X_1,X_2,…,X_k有如下的关系:(1.1) Y=β_0+β_1X_1…+β_kX_k+e其中e是随机误差,满足条件:E(e)=0,D(e)=σ~2。 称Y=β_0+β_1X_1+…+β_kX_k为Y关于X_1……,X_k的回归方程. 相似文献
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钟玉婷 《沙漠与绿洲气象(新疆气象)》2016,10(3):77-82
降水是大气中主要和次要污染物的重要收集器,是大气中颗粒物和气态污染物最好的清除剂。本文利用离子色谱分析了2011年伊宁市90个降水样品,结果表明,该区降水pH月均值在5.27—7.1之间,年均值为6.26,电导率变化范围为34.64~63μs·cm~(-1),年均值为45.7μs·cm~(-1)。降水中主要离子浓度排序为Ca~(2+)SO_4~(2-)NH_4~+Mg~(2+)Cl~-NO_3~-Na~+F~-K~+,Ca~(2+)是最主要的阳离子,年均值为421.76μeq·L~(-1),SO_4~(2-)是最主要的阴离子,年均值为149.09μeq·L~(-1),表明伊宁降水中的致酸物质主要是硫酸盐。总离子浓度季节变化特征表现为春夏季高,秋冬季低,总离子浓度明显低于乌鲁木齐和沈阳,与北京类似,远高于杭州、广州,表明伊宁降水污染比北方城市轻,但是陆源贡献远大于南方城市。FA平均值为0.003,表明99.7%的降水酸度被碱性成分中和,NF计算结果表明Ca~(2+)的中和能力最强,其次是NH_4~+。从相关分析和因子分析来看,F~-、SO_4~(2-)、NO_3~-、Cl~-、NH_4~+主要受人为源的控制,Ca~(2+)、K~+主要来源于土壤和浮尘,Na~+、Mg~(2+)主要来源为土壤盐碱化、风化、干旱浮尘等自然源。 相似文献
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突变论Thom分类定理中的第四种初等变换即蝴蝶突变模型,其标准形式为 X_1~5+C_3X_1~3+C_2X_1~2+C_1X_1+C_0=0 (1)式中C_3<0。(1)式的相空间是五维的,控制空间是四维的,其所对应的控制参数有四个,分别为 C_3:蝴蝶因子(butterfly factor) C_2:偏倚因子(bias factor) C_1:剖分变量(splitting variable) C_0:正则变量(normol variable) 状态变量有一个即平衡态X_1,反映平衡态X_1的控制方程(1)式是一个超曲面,它不能在通常的三维空间中用一幅几何图形画出其分歧点集(bifurcation set),必须固定C_3、C_2后才可能在二维的控制相平面(C_0,C_1)中画出它的分歧点集。为了得到这个分歧点集的分析表达式,我们作如下推导: 相似文献
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用树木年轮重建博尔塔拉河流域的降水量序列 总被引：3，自引：1，他引：3
根据采自天山北坡西段博尔塔拉河流域18个采点的树木年轮样本,建立了每个采点的3种年表。通过相关普查分析,发现年表序列与上年10月至当年7月降水相关显著。用查干哈尔尕(t+1)、依和浑迪(t、t+1)、哈夏(t+2)4个树轮标准化年表序列可较好地重建该流域392a的该时段的降水量。分析重建结果发现:在这392a中,具有较明显的5个干期和6个湿期:有2a、3a、4a、12a、29a和43a的变化准周期:在1730,1753,1778和1831年发生突变。 相似文献
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空盒气压表体积小、重量轻、便于携带、不易损坏 ,尤其在野外流动作业时显得更为便利。一台合格的空盒气压表有一张合格检定证书 :①温度系数 + 0 0 3ｈＰａ/℃ ;②数值修正值 (见表 1 ) ;③补充修正值 -0 0 1ｈＰａ。表 1 数值修正值 /ｈＰａ气压修正值气压修正值90 091092 093094095 096 0970+0 1+0 2+0 3+0 3+0 4+0 5+0 4+0 398099010 0 010 1010 2 010 3010 4010 5 0+0 3+0 2+0 1- 0 1- 0 3- 0 5- 0 7- 0 9 利用空盒气压表测量大气压力时 ,首先将表置于需要测量的位置上 (水平放置 ) ,经一段时间使表适应周围的… 相似文献
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Changes in soil organic carbon stocks as affected by cropping systems and cropping duration in China’s paddy fields: a meta-analysis 总被引：4，自引：0，他引：4
Great uncertainties remain in the impact of cropping systems on soil organic carbon (SOC) stocks in paddy fields that hold a large potential for carbon (C) sequestration. In this study, a meta-analysis was performed to examine trends on SOC stocks in unfertilized and fertilized fields from three of the most common rice cropping systems in China. Results showed that rice cropping without any nutrient application (Control) significantly increased SOC stocks by 9% compared to the initial level in double rice cropping systems (DR), whereas no significant effects were observed in single rice cropping systems (SR) and rice-upland crop rotation systems (RU). Paddy soils sequestered C in all the three cropping systems under inorganic NPK fertilization, and the magnitude of the increase in SOC stocks was in the order DR > RU > SR. Soil C stocks increased with the increasing cropping duration. Continuous rice cropping for more than 20?years led to average SOC gains of 15% and 23% in the control and NPK treatments, respectively. Furthermore, it seems that C sequestration was still occurring in the longest fields from the included studies. Thus, no SOC saturation trend was found over the investigated cropping duration. However, the negative relationship between SOC changes and their initial C stocks suggests indirectly the possibility of SOC saturation in paddy fields. 相似文献
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为提高水稻作物生长模型中淹涝胁迫对水稻生长和产量影响的定量评估能力,通过开展水稻盆栽淹涝试验,研究了不同淹涝胁迫程度对粳稻和籼稻植株叶片光合性能的影响,并将两者之间的关系进行了定量化,结果表明:1)两种水稻植株叶片的光量子效率AQE、最大光合速率P_m均随淹涝天数的增加而明显下降,全淹处理的下降幅度较大,受全淹处理8天后平均下降幅度近五成,而半淹处理的下降幅度较小,半淹处理8天后平均降幅约一成左右;叶片基础荧光F_0、最大荧光产额F_m和最大光化学效率F_v/F_m也均随着淹涝胁迫天数的增加出现不同程度的降低。2)植株叶片光量子效率和最大光合速率随淹涝深度和淹涝天数变化可用定量关系模型y=1-aH-bH~3T来描述,用独立的试验资料对该模型进行检验后表明,模型的模拟值与实测值有很好的一致性,两者的相关系数高、RMSE值低,模拟效果令人满意。3)全淹处理下,水稻植株叶片最大光合速率P_m和最大荧光产额F_m下降幅度具有较好的相关性,可运用荧光测定的信息来快速估计淹涝胁迫对水稻叶片光合速率影响的程度。本研究可为改进水稻模型中淹涝胁迫条件下的水稻干物质累积和产量的模拟提供依据。 相似文献
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Naresh Kumar Soora P. K. Aggarwal Rani Saxena Swaroopa Rani Surabhi Jain Nitin Chauhan 《Climatic change》2013,118(3-4):683-699
A simulation analysis was carried out using the InfoCrop-rice model to quantify impacts and adaptation gains, as well as to identify vulnerable regions for irrigated and rain fed rice cultivation in future climates in India. Climates in A1b, A2, B1 and B2 emission scenarios as per a global climate model (MIROC3.2.HI) and a regional climate model (PRECIS) were considered for the study. On an aggregated scale, the mean of all emission scenarios indicate that climate change is likely to reduce irrigated rice yields by ~4 % in 2020 (2010–2039), ~7 % in 2050 (2040–2069), and by ~10 % in 2080 (2070–2099) climate scenarios. On the other hand, rainfed rice yields in India are likely to be reduced by ~6 % in the 2020 scenario, but in the 2050 and 2080 scenarios they are projected to decrease only marginally (<2.5 %). However, spatial variations exist for the magnitude of the impact, with some regions likely to be affected more than others. Adaptation strategies comprising agronomical management can offset negative impacts in the near future—particularly in rainfed conditions—but in the longer run, developing suitable varieties coupled with improved and efficient crop husbandry will become essential. For irrigated rice crop, genotypic and agronomic improvements will become crucial; while for rainfed conditions, improved management and additional fertilizers will be needed. Basically climate change is likely to exhibit three types of impacts on rice crop: i) regions that are adversely affected by climate change can gain in net productivity with adaptation; ii) regions that are adversely affected will still remain vulnerable despite adaptation gains; and iii) rainfed regions (with currently low rainfall) that are likely to gain due to increase in rainfall can further benefit by adaptation. Regions falling in the vulnerable category even after suggested adaptation to climate change will require more intensive, specific and innovative adaptation options. The present analysis indicates the possibility of substantial improvement in yields with efficient utilization of inputs and adoption of improved varieties. 相似文献
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采用静态箱-气相色谱法在江汉平原开展早稻、晚稻、中稻、虾稻和再生稻5种稻作类型温室气体排放监测试验,研究不同稻作模式下稻田CH4和N2O排放特征、总增温潜势及温室气体排放强度,为准确评估稻田生态系统温室气体排放提供参考依据。结果表明:CH4排放集中在水稻前期淹水阶段,排放峰值最高为虾稻（85.7 mg·m-2·h-1）,较其他稻作模式高71.7%~191.5%。N2O排放峰值主要出现于中期晒田和施肥阶段,排放峰值最高为再生稻（1100.7 μg·m-2·h-1）,较其他稻作模式高16.8%~654.9%。CH4累积排放量从大到小依次为虾稻、再生稻、早稻、晚稻、中稻;N2O累积排放量从大到小依次为再生稻、早稻、晚稻、中稻、虾稻;总增温潜势从大到小依次为虾稻、再生稻、早稻、晚稻、中稻;温室气体排放强度从大到小依次为虾稻、早稻、再生稻、晚稻、中稻。CH4排放占比为82.9%~99.0%,稻虾田高排放主要原因为持续淹水时间长、秸秆还田和饲料投入,探究该模式CH4减排举措最为关键;中稻由于水旱轮作,稻田温室气体排放最低,可作为低碳减排的主要稻作类型。 相似文献
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Ｍｏｄｅｌ ｆｏｒ Ｍｅｔｈａｎｅ Ｅｍｉｓｓｉｏｎ ｆｒｏｍ Ｒｉｃｅ Ｆｉｅｌｄｓ ａｎｄ Ｉｔｓ Ａｐｐｌｉｃａｔｉｏｎ ｉｎ Ｓｏｕｔｈｅｒｎ ＣｈｉｎａＤｉｎｇＡｉｊｕａｎｄＷａｎｇＭｉｎｇｘｉｎｇ（ＩｎｓｔｉｔｕｔｅｏｆＡｔｍｏｓｐｈｅｒ... 相似文献
16.
Youngseob Kim Karine Sartelet Christian Seigneur 《Journal of Atmospheric Chemistry》2009,62(2):89-119
Two recent gas-phase chemical kinetic mechanisms for tropospheric ozone formation, one based on the lumped-structure approach (CB05) and the other based on the lumped-molecule approach (RACM2), are compared for simulations of ozone over Europe. The host air quality model is POLAIR3D of the Polyphemus modeling platform. A one-month period (15 July to 15 August 2001) is simulated. Model performance is satisfactory with both mechanisms. Overall, the two mechanisms give similar results with a domain-averaged difference of 3 ppb and a mean fractional absolute difference of 5% (values averaged over the month for the daily 8-h average maximum ozone concentrations). This difference results from different treatments in the two mechanisms for both inorganic and organic chemistry. Differences in the treatment of the inorganic chemistry are due mainly to differences in the kinetics of two reactions: NO + O3 \(\longrightarrow\) NO2 + O2 and NO + HO2 \(\longrightarrow\) NO2 + OH. These differences lead to a domain-averaged difference in ozone concentration of 5%, with RACM2 kinetics being more conducive to ozone formation. Differences in the treatment of organic chemistry lead to a domain-averaged difference in ozone concentration of 3%, with CB05 chemistry being more conducive to ozone formation. This average difference results in part from compensating effects among various VOC classes and some significant differences are identified at specific locations (the coastline of northern Africa and eastern Europe: 9%) and for specific organic classes (aldehydes, biogenic alkenes and aromatics). Differences in the treatment of the organic chemistry result from various aspects. For some VOC classes, such as aldehydes and biogenic alkenes, the more detailed explicit treatments using more model species in RACM2 lead to either greater or lower reactivity depending on the assumptions made for the oxidation products. For other VOC species, such as aromatics, the assumptions made about the major chemical oxidation pathways (aromatic alcohol formation in CB05 vs. ring opening in RACM2) affect the ozone formation significantly. Reconciliation of different chemical kinetic mechanisms will require experimental data to reduce current uncertainties in the kinetic (e.g., NO oxidation) and mechanistic (e.g., aromatics oxidation) representations of major chemical pathways. 相似文献
17.
This paper reports results of a comparison of two popular rice growth models- Ceres-Rice and ORYZA1N for the same input conditions. Both models use different approaches for simulating growth and yield, are sensitive to climate change parameters, and represent two major schools of crop modelling. A dataset of 32 experiments consisting of 98 treatments was assembled from an extensive literature search. These experiments were conducted over the period of 1980–1993 in diverse Indian locations from 11° N–33° N. The treatments varied in N management, sowing dates, varieties and seasons. The flowering duration in the dataset varied between 37 and 86 days and grain yields between 2587 kg ha–1 and 8877 kg ha–1. Seven treatments from this dataset, one for each variety, were selected for calibration. The genetic coefficients of different varieties used in the analysis for both models were estimated from this short-listed dataset by repeated iterations until a close match between simulated and observed phenology and yield was obtained in these treatments. Similarly 11 treatments with zero or low N applications were used for calibration of initial soil N for different locations. The remaining 80 treatments were used for validation of the models. Both models predicted satisfactorily the trends of leaf area and dry matter growth, grain number, days to flowering and grain yields. Simulated yields were within +15% of the measurements. Considering that the field measurements also generally have 10–15% error and that the treatments widely varied in weather conditions, particularly in temperature, it was concluded that both models are adequate to simulate the effects of climate change on rice yields in diverse agro-environments of India that are free from all pests. 相似文献
18.
2018年在黑龙江省庆安县选用寒地水稻龙粳31品种进行淹水试验,在拔节孕穗期、抽穗开花期,分别设定3个淹水深度（1/3株高、2/3株高、3/3株高）、2个淹水历时（3 d、7 d）共12个淹水处理,测定淹水前后的株高、叶面积、干物质及收获后的每穗粒数、结实率、千粒重及产量等。结果表明：水稻淹水后,株高、叶面积指数、干物质平均增长量基本高于同时期对照组,在一定程度上可以说明适度的淹涝胁迫对水稻植株生长具有促进作用,拔节孕穗期各项与对照组相比的增长程度均低于抽穗开花期;不同淹涝胁迫均导致水稻减产,拔节孕穗期全淹没7 d减产最严重,穗结实粒数仅55粒,千粒重16.9 g,远低于对照,减产率高达70%,抽穗开花期全淹没7 d减产也较严重,穗结实粒数为71粒,千粒重略低,但单位面积有效穗数最少,为2.83×106穗,减产率达57%;淹水深度1/3 h、2/3 h、3/3 h处理的平均减产率依次为16%、18%、48%,淹水持续3 d、7 d的平均减产率分别为21%、33%,可见随着淹水深度加深、淹水历时加长,水稻减产幅度加大;淹涝胁迫条件下,拔节孕穗期水稻产量的下降幅度大于抽穗开花期,导致两个发育期减产的主要产量构成因素分别为穗结实粒数、单位面积有效穗数。 相似文献
19.
Mitigation options for methane, nitrous oxide and nitric oxide emissions from agricultural ecosystems 总被引：9，自引：0，他引：9
Zheng Xunhu Wang Mingxing Wang Yuesi Shen Renxing Li Jing J. Heyer M. Koegge H. Papen 《大气科学进展》2000,17(1):83-92
1.IntroductionNitrousoxide(N,O)andmethane(CH.)arethemostimportantgreenhousegassesintheatmospherewithitscontributiontoglobalwarmingjustlowerthanCO2.Theirconcentrationsinatmospherehavebeennotedtoincreasecurrentlyattherateof0.25%yr--'andl.02%yr',respectively(IPCC,1995).Atpresent,theincreaseofNZOandCH4intheatmospherehasbeenestimatedtoaccountfor20--25%oftheglobalwarming(FAO&IAEA,1992;Bailes&Bridges,1992).NOdoesnotabsorbradiationdirectlyintheatmosphere,buttheincreasingconcentrationofNOmay… 相似文献
20.
M. Ciężka M. Modelska M. Górka A. Trojanowska-Olichwer D. Widory 《Journal of Atmospheric Chemistry》2016,73(1):61-80
The chemical compositions (Na+, NH4 +, K+, Mg2+, Ca2+, Cl?, NO2 ?, NO3 ?, SO4 2?, HCO3 ?) of wet precipitation and nitrogen isotope compositions δ15N(NH4 +) were studied from January to December 2010 in Wroc?aw (SW Poland). Results of a principle component analysis show that 82 % of the data variability can be explained by three main factors: 1) F1 (40 %) observed during vegetative season (electrical conductivity, HCO3 ?, NO3 ?, NO2 ?, NH4 + and SO4 2?), mainly controlling rainwater mineralization; 2) F2 (26 %) observed during vegetative and heating seasons (K+, Ca2+ and Mg2+), probably representing a combination of two processes: anthropogenic dusts and fertilizers application in agricultural fields, and 3) F3 (16 %) reported mainly during heating season (Na+ and Cl?) probably indicating the influence of marine aerosols. Variations of δ15N(NH4 +) from ?11.5 to 18.5?‰ identify three main pathways for the formation of NH4 +: 1) equilibrium fractionation between NH3 and NH4 +; 2) kinetic exchange between NH3 and NH4 +; 3) NH4 + exchange between atmospheric salts particles and precipitation. The coupled chemical/statistical analysis and δ15N(NH4 +) approach shows that while fossil fuels burning is the main source of NH4 + in precipitation during the heating season, during the vegetative season NH4 + originates from local sewage irrigation fields in Osobowice or agricultural fertilizers. 相似文献