常年淹水稻田甲烷产生潜力和产生途径的季节变化

甲烷的减排问题已成为各国政府和科研人员关注的焦点。稻田是温室气体甲烷的重要排放源,甲烷产生是排放的前提条件,主要有乙酸发酵和CO₂/H₂还原两条途径。常年淹水稻田甲烷排放量高,减排潜力大,但关于这类稻田甲烷产生途径的季节变化规律尚少见报道。于四川省资阳市的常年淹水稻田,采集水稻4个重要生育期(分蘖期、孕穗期、抽穗期、成熟期)的新鲜土样,通过室内厌氧培养试验观测了甲烷产生潜力,并采用稳定性碳同位素方法和氟甲烷(CH₃F,2%)抑制法,量化CO₂/H₂产甲烷的碳同位素分馏系数(α(CO₂/CH₄)),从而定量评估乙酸产甲烷途径的相对贡献率(?乙酸)。结果表明：添加CH₃F显著降低甲烷产生,甲烷产生潜力在成熟期最大,变化范围为3.22～12.71μg·g^–1·d^–1;产生CH₄的δ¹³C值(δ¹³CH_...     

易利用态有机物质对水稻土甲烷排放的激发作用

为探讨外源有机物质对淹水稻田土壤CH4排放的激发作用,对比不同外源有机物质对土壤CH4排放的贡献差别,本研究选取3种标记的易利用态有机物(葡萄糖、乙酸和草酸)分别加入水稻土,进行了为期1个月的培养。结果表明:培养30 d后不同处理CH4的累计排放量差异显著(P0.05),其中,乙酸葡萄糖草酸对照;双因素方差分析结果显示,外源有机物质的添加加速了土壤易利用态有机质的矿化(即产生正激发效应);不同处理条件下激发作用产生的CH4分别占各处理CH4总累计排放量的73.3%(葡萄糖处理)、71.5%(乙酸处理)和40.9%(草酸处理),且CH4排放量与CH4激发效应之间极显著正相关关系说明土壤CH4排放主要要来自于土壤原有机质的分解,外源有机物质可能主要对土壤微生物活性及代谢途径有影响。     

High-Time Resolution Analysis of Diel Variation in Methane Emission from Flooded Rice Fields

Methane (CH₄) emission from flooded rice fields was measured hourly over 24 h for rice (Oryza sativa L.) seasons in 2008 and 2009. The objectives of this study were to identify typical diel variation in CH₄ emission and to estimate the best time of day for optimum extrapolation of daily CH₄ emission. Our results showed distinct diel variation in CH₄ emission, which exhibited a maximum at 14:00–15:00 and a minimum at midnight. About 5.2–5.6% of total CH₄ emitted per day (110–160 mg CH₄ m^?2 d^?1) was released at 14:00–15:00. The diel pattern of CH₄ emission resembled that of air temperature (T_a). The T_a coupled with solar radiation could cause a difference in partial pressure of CH₄ (DPPC) through the gas conduit of the plant. The best extrapolation of daily CH₄ emission was achieved with data observed at 10:00–11:00. We concluded that DPPC-induced CH₄ emission is an important mechanism causing diel variation.     

Soil Phosphorus Tests for Flooded Rice Grown in Contrasting Soils and Cropping History

Soil phosphorus (P) tests for flooded rice (Oryza sativa L.) generally present uncertainties for estimating P availability. Bray 1, 1% citric acid, Mehlich 3, Olsen extractants (dry samples), and Bray 1 extractant after 3 days (BI3) and 7 days (BI7) of anaerobic incubations were evaluated to estimate P availability for rice in 43 Uruguayan soils. Field trials were conduced at each site (0, 13, 26, and 39 kg P applied ha^?1). Relative yield and absolute and relative yield increases were determined. Extracted P was variable for the different tests. For silty soils, P availability was better estimated by citric acid, Mehlich 3, and Bray 1, with similar soil P critical concentrations (6?8 mg P kg^?1). The BI3 and BI7 tests showed greater soil P critical concentration but poorer correlations with yield indexes. This study contributes to the scientific basis of P fertilization for flooded rice, promoting more effective fertilizer use and minimizing environmental P losses.     

不同温度下尿素对水稻土甲烷产生及相关古菌群落的影响

水稻田是大气甲烷的重要排放源。尿素氮肥施用是提升水稻产量和品质的重要措施,但其对稻田土壤中产甲烷古菌的影响规律仍不清楚。通过模拟水稻生长季节可能的田间温度变化,本文对水稻土进行施加尿素（400 mg N/kgdry soil）与未施加尿素（0 mg N/kgdry soil）两个处理,并在15℃、25℃、37℃以及50℃四个温度下进行为期100d的厌氧培养,定期测定了培养过程中产甲烷累积量以及土壤理化因子pH、铵氮以及有机碳的变化。并运用基于16S rRNA基因的T-RFLP（末端限制性片段多态性分析）技术分析了产甲烷过程中古菌群落结构随时间的变化情况。结果表明,在中低温范围内（15℃-37℃）,尿素对水稻土产甲烷有抑制作用,但在50℃高温下尿素对水稻土产甲烷量没有显著影响。尿素可能通过改变产甲烷古菌群落结构来影响产甲烷,在15℃-37℃范围内,尿素降低了水稻土产甲烷古菌群落的稳定性,增大了其在不同时间的差异性;而在50℃高温时,尿素对水稻土产甲烷古菌稳定性和差异性的影响不明显。不同温度下,尿素均降低了甲烷八叠球菌（Methanosarcinaceae）的丰度,且随着温度的变化,尿素对水稻土产甲烷机制的改变可能没有影响。     

不同温度下尿素对水稻土甲烷产生及相关古菌群落的影响

水稻田是大气甲烷的重要排放源。尿素氮肥施用是提升水稻产量和品质的重要措施,但其对稻田土壤中产甲烷古菌的影响规律仍不清楚。通过模拟水稻生长季节可能的田间温度变化,本研究设置水稻土施加尿素(N,400 mg/kg干土)与未施加尿素两个处理,在15℃、25℃、37℃以及50℃下进行为期100天的厌氧培养,定期测定了培养过程中甲烷累积量以及土壤理化因子如p H、NH_4~+-N以及有机碳的变化,并运用基于16S r RNA基因的T-RFLP(末端限制性片段多态性分析)技术分析了产甲烷过程中古菌群落结构随时间的变化情况。结果表明:在中低温范围内(15~37℃),尿素对水稻土产甲烷有抑制作用,但在50℃高温下尿素对水稻土产甲烷量没有显著影响。尿素可能通过改变产甲烷古菌群落结构来影响甲烷的产生,在15~37℃范围内,尿素降低了水稻土产甲烷古菌群落的稳定性,增大了其在不同时间的差异性;而在50℃高温时,尿素对水稻土产甲烷古菌稳定性和差异性的影响不明显。不同温度下,尿素均降低了甲烷八叠球菌(Methanosarcinaceae)的丰度,且随着温度的变化,尿素对水稻土产甲烷机制的改变可能没有影响。     

温度对不同生态系统土壤甲烷氧化过程和甲烷氧化细菌的影响

温室气体的大量人为排放导致了近百年来的全球气候变化。甲烷是重要的温室气体,随着全球气温升高,甲烷排放量会随之增加,进一步加剧了全球温室效应。土壤是甲烷重要的源和汇,土壤中的甲烷氧化细菌在平衡甲烷的释放过程中发挥着关键作用。探究温度变化对土壤甲烷氧化能力的影响成为近年来的研究热点。本文综述了温度对土壤甲烷氧化过程以及甲烷氧化细菌的影响,分析了在不同温度下,各生态系统中的土壤甲烷氧化及甲烷氧化细菌响应特点和规律,比较了不同生态系统中土壤发生甲烷氧化的温度范围以及甲烷氧化菌株的生长温度范围。综述结果表明,不同生态系统能够发生甲烷氧化的温度范围不同;在能发生甲烷氧化的温度范围内,甲烷氧化速率随温度升高而增加;培养温度与土壤原位温度越相近时,甲烷氧化响应较为灵敏。与温度对甲烷氧化过程的影响类似,甲烷氧化细菌的丰度也随着温度升高而增加,并与增温幅度、优势甲烷氧化细菌的原位生长温度密切相关。土壤中的II型甲烷氧化细菌对温度较敏感,随着温度升高,II型甲烷氧化细菌丰度增加,因此,温度会通过影响甲烷氧化细菌的丰度和群落结构,从而影响甲烷氧化过程。但温度是否仅通过调控优势菌种更替来改变土壤甲烷氧化能力目前还尚未定论,未来需要进一步探究。本文讨论了土壤甲烷氧化过程对温度的响应及其微生物机制,可为全面解析全球变暖下的土壤甲烷氧化过程的变化提供参考。     

华中稻田甲烷排放的施肥效应及施肥策略

研究了实施几种不同比例有阶肥及化肥的施肥方案对稻田甲烷排放的影响。在维持氮、磷、钾含量其本不变时，施较多的有机肥是甲烷排放率高的重要原因，而施较多化肥则能降低甲烷排放；同样是有机肥，已在沼气池中发酵后的沼渣经干燥后对稻田甲烷徘放的正效应要大大低于“新鲜”有机肥；有机肥数量及性质的改变对甲烷排放的影响程度要远远大于改变化肥量对甲烷排放的影响，即有机肥的数量及性质显影响稻田甲烷排放的主要因素；控制甲烷排放的方法应重点放在控制有机肥的施用上，沼渣作为一种再生性的资源，具有多种优点，能够用来代替目前常用的有机肥。沼渣肥与化肥结合施用可能是降低稻田甲烷排放的有效措施。     

黑龙江不同类型土壤对水稻生长发育及产量的影响

采用盆栽试验方法,研究黑龙江省不同类型土壤对水稻生长发育及产量的影响。结果表明:不同类型土壤水稻分蘖消长动态、干物质积累及叶面积指数存在差异,对水稻穗数、穗粒数影响差异显著,对水稻产量影响差异达极显著水平,水稻产量排序为白浆土>草甸土>草甸黑土>黑土>盐碱土。     

有机物料对稻田土壤团聚体及有机碳分布的影响

通过连续5年定位试验,以紫云英、秸秆和商品有机肥等有机物料还田的稻田土壤为对象,研究有机物料还田后不同物理分组下土壤组成特点和有机碳变化特征。结果表明,稻田土壤团聚体主要分布在2~0.25mm与0.25~0.053mm粒级,团聚体颗粒有机碳含量随着粒径的减小而减少。有机物料还田可提高0.25~0.053mm和0.053mm粒级团聚体有机碳的含量,紫云英、秸秆、商品有机肥等有机物料可通过提高土壤微团聚体有机碳含量而增加土壤碳库。有机物料施用增加土壤轻组组分颗粒含量,减少重组组分颗粒含量,有助于土壤轻组组分的形成。稻田土壤轻组颗粒有机碳含量与0.25mm和0.053mm团聚体颗粒有机碳含量呈显著相关,与2~0.25mm团聚体颗粒有机碳含量呈极显著相关。稻田土壤施用紫云英、秸秆和商品有机肥等有机物料,可有效提高土壤微团聚体和轻组成分颗粒含量,增加土壤微团聚体和轻组有机碳含量,改变稻田土壤有机碳库组成特征。     

Rice Straw Composting and Its Effect on Soil Properties

In Egypt, recycling rice straw and organic wastes is of great concern as well as improvement of soil properties. Rice straw compost could improve both organic waste recycling and soil quality. The aim of this study was to evaluate the effect of the rice straw compost, with or without water treatment residuals (WTR), on soil chemical properties and dry weight of canola. The results showed that the addition of rice straw compost and WTR decreased soil salinity and increased Ca⁺², K⁺ and organic matter. The addition of compost and WTR (2:1 wet weight ratio) at level of 10 g dry weight kg^?1 dry soil gave the best reduction in soil salinity compared to compost or WTR only or for level 10 g dry weight kg^?1 dry soil. The results also showed that the available P decreased with the application of WTR while it increased with the application of compost. The study demonstrated that the dry weight and relative increase (R.I %) of dry weight of canola plants increased with the application of WTR and compost to soil. Combinations of WTR and compost to soils had a greater effect on increasing yield and improved the efficiency of WTR on soil properties.     

大米草玉米的耐盐效果及对盐渍化土壤的改良试验

土壤盐渍化已成为限制农作物生长、发育和产量的最主要非生物胁迫因素之一。培育耐盐碱作物是解决这一问题的有效途径。通过田间试验,研究了大米草玉米耐盐碱能力和改良盐渍化土壤的效果。结果表明,筛选出的适应盐渍土种植的优良大米草玉米自交系具有很强的生长势和耐盐碱性,耐盐能力为11.76g/kg。根据作物生长势好,生长势强和生长势特强3种长势试验地块的测试结果,3种地块土壤脱盐率依次为15.7%,22.9%和34.5%,表明通过培育优选出的大米草玉米不仅具有较强的耐盐碱性能力,而且还对改良盐渍化土壤具有一定的效果。     

Influence of Urea and Ammonium Sulfate on Soil Acidity Indices in Lowland Rice Production

Urea and ammonium sulfate are principal nitrogen (N) sources for crop production. Two field experiments were conducted during three consecutive years to evaluate influence of urea and ammonium sulfate application on grain yield, soil pH, calcium (Ca) saturation, magnesium (Mg) saturation, base saturation, aluminum (Al) saturation, and acidity (H + Al) saturation in lowland rice production. Grain yield was significantly influenced by urea as well as ammonium sulfate fertilization. Soil pH linearly decreased with the application of N by ammonium sulfate and urea fertilizers. However, the magnitude of the pH decrease was greater by ammonium sulfate than by urea. The Ca and Mg saturations were decreased at the greater N rates compared to low rates of N by both the fertilizer sources. The Al and acidity saturation increased with increasing N rates by both the fertilizer sources. However, these acidity indices were increased more with the application of ammonium sulfate compared with urea. Rice grain yield had negative associations with pH, Ca saturation, Mg saturation, and base saturation and positive associations with Al and acidity saturation. This indicates that rice plant is tolerant to soil acidity.     

长期施肥对湖南稻田甲烷排放的影响

采用静态箱-气相色谱法对长期不同施肥处理的稻田甲烷排放进行了手动观测。结果表明，不同施肥处理的稻田甲烷排放具有一致的规律，混施有机肥的处理甲烷排放大于单施氮肥的处理，同施用稻草相比，发酵猪粪处理的甲烷排放较少。文章还对影响稻田甲烷排放的因素进行了讨论。     

不同覆盖旱作水稻对后茬大麦生长和土壤氮素的影响

通过田间试验研究水稻不同覆盖旱作栽培方式对后茬大麦生长及土壤氮素动态变化的影响。结果表明，盖草处理后茬大麦表层土壤硝态氮含量最高，而土壤铵态氮含量由高到低依次为：水作〉盖草〉覆膜〉裸露，且硝态氮、铵态氮从表层（0～20cm）到底层（60～80cm）依次降低。具有明显的层次性。各处理都表现出0～40cm土层氮素表观盈余，水作、盖草和裸露处理后茬分别比覆膜处理后茬高40．5％，39．5％和36．1％。大麦籽粒产量以盖草处理后茬摄高，分别比水作后茬和裸露后茬增加837kg／hm^2和251kg／hm^2。后茬大麦各生育阶段对氮素的累积吸收量均以前茬盖草早作处理最高。覆膜、盖草和裸露旱作水稻后茬大麦的氮肥利用率分别比水作稻后茬大麦高16．1％，17．5％和13．8％。土壤氮素转化和大麦产量均表明，半腐解秸秆覆盖旱作水稻-大麦轮作是一种较合理的种植模式。     

Effect of Dairy Manure and Rice Planting Methods on Yield,Soil Quality,Water-Use Efficiency,and Economics of Rice and Succeeding Wheat Crop

Presently, directly seeded rice (DSR) is preferred over transplanted puddle rice (TPR) because of its high water-use efficiency (WUE). Also, TPR deteriorates the soil physicochemical properties, so in these conditions dairy manure has been used to reduce bulk density, increase hydraulic conductivity, and improve soil nutrient status. Experiments were conducted to study the effects of manure and rice planting methods on yield, soil quality, WUE, and economics of rice and the succeeding wheat crop. Results showed that TPR increased kernel yield by 10.26% compared to DSR. However, it deteriorated soil physical properties and reduced soil nitrogen by 7.31% at 0–15 cm deep and nitrate concentration by 61.40% at 0–35 cm deep, which significantly reduced succeeding wheat yield by 18.21%. The residual soil organic fertility after crop harvest was proportional to the level of dairy manure used.     

Effects of Controlled Release Urea on the Yield and Nitrogen Nutrition of Flooded Rice

Nitrogen (N) loss is one of the key problems faced by rice farmers, and Nitrogen-use efficiency in rice is often poor as a result of high N loss through volatilization, leaching, and denitrification. One of the ways to improve N efficiency is by using controlled-release urea (CRU). The CRU generally outperformed granular urea fertilizer in reducing N losses, stimulating plant growth, and increasing N concentrations. A field experiment with the flooded rice variety MR220 was conducted to compare the effect of six different types of CRU fertilizers on yield and N nutrition of a flooded rice cultivar. Bakau series soil (Typic Tropaquept) was used in this study. Rice plants were grown in a cylindrical culvert measuring 90 cm in diameter by 60 cm in height, and all culverts were filled with soil (approx. 210 kg). The soil was flooded and preincubated for 3 weeks to stabilize physiochemical properties before sowing. The experiment was carried out over two planting seasons on the same plot using a completely randomized design (CRD) and was replicated three times. The CRUs evaluated were CDU Uber-10, Meister-20, Meister-27, humate-coated urea, Duration type V, and sulfur-coated urea (gold–N). Fertilizer was applied once throughout the study. For both seasons, CRU-treated plants had significantly greater rice yields [6 t ha^?1 (first planting harvest) and 6.2 t ha^?1 (second planting harvest)] than urea-treated plants [3.7 t ha^?1 (first planting harvest) and 2.2 t ha^?1 (second planting harvest)], respectively. The N accumulations in rice straw and rice grains of the CRU-treated plot were significantly greater than in the control. It can be inferred that CRU performs significantly better than granular urea. This finding is important, considering the usually high N losses in rice-growing areas.     

覆草对坡地果园土壤及柑桔产量与品质的影响

1996～1998年在榕江县忠诚果树试验场,进行了覆草对坡地果园土壤及柑桔产量与品质的影响研究。结果表明:覆草能减少土壤水分蒸发,保持土壤水分,稳定土壤温度;防止土壤板结,协调土壤毛管孔隙和通气孔隙比例;增加土壤有机质和养分含量;以及提高柑桔产量与品质。     

海水稻根际效应对滨海盐碱地土壤氨氧化微生物的影响

滨海盐碱地的特殊环境严重限制了土壤氮素转化和利用。微生物介导的水稻根际氨氧化过程是盐碱稻田土壤氮循环的关键过程,但限于研究盲点和技术不足,海水稻根际效应对滨海盐碱地土壤氨氧化微生物群落结构的影响仍少有报道。据此,本研究以“海稻86”为研究对象,分别设置低盐浓度(2 g·kg^–1)和高盐浓度(6 g·kg–1)两组处理进行盆栽试验。结果显示：种植海水稻70 d后,高盐和低盐处理根际土壤的pH分别下降了0.82和0.70个单位,土壤有机质(SOM)含量下降了6.41和4.46 g·kg^–1,腐殖质(HU)含量提高了5.76和4.45 g·kg^–1,全氮(TN)含量减少0.46和0.37 g·kg^–1,表明海水稻可通过降低盐碱地土壤pH,加速有机质分解转化,提高土壤氮循环速率。水稻根际作用可显著提高土壤微生物生物量碳(MBC)、微生物生物量氮(MBN)和微生物呼吸强度,并在种植第55天达到最高,在高盐处理中分别达到850.0 mg·kg^–1、72.2 mg·kg^–1     

不同节水稻作模式对土壤理化特性和土壤酶活性影响研究

针对南方丘陵区季节性干旱现状与目前稻田单一化的连作耕作制度对农田环境造成的不利影响因素,通过4a田间定位试验研究了节水稻作模式下土壤理化性状和土壤酶活性变化规律影响.结果表明,与该区常规稻作模式相比.在试验设计范围内,节水稻作模式下稻田的土壤理化性状明显改善,随着耕种年限增加,土壤容重下降,而孔隙度增加.土壤通透性增强,有效阻止土壤次生潜育化和土壤酸化.提高了土壤pH值;就土壤酶活性而言,节水稻作模式处理酶活性常规稻作模式相比.除转化酶外,其它酶活性均有不同程度的增加,尤其对磷酸酶与脲酶影响最大.