Effects of Plastic Film Mulching on Physical Characters of Soil and Yield and Yield Components of Sweet Potato

Field experiments were carried out to study the effects of plastic film mulching on soil physical characters, including soil temperature, soil moisture content and soil bulk density, and yield and yield components of sweet potato. The results showed that plastic filming mulching increased soil temperature. Considering the soil temperature-increasing effect, the treatments ranked as black plastic film treatment 〉 white plastic film treatment 〉 control. However, with the deepening of soil layer, the warming effect of plastic film mulching was weakened. Black or white plastic film mulching was conducive to low T/R value, especially in the early growth stage of sweet potato. Plastic film mulching significantly improved the storage root yield of sweet potato. In terms of yield-improving effect, the treatments ranked as black plastic film treatment 〉 white plastic film treatment 〉 control. The storage root num- ber per plant showed a downward trend, but the weight of single storage root was increased.

Effects of Green Manure Mixed Cropping Patterns on Physical and Chemical Properties of Soil and Economic Characters of Flue-cured Tobacco

[Objective] The aim was to clear the suitable green manure cropping pat- terns in Xiangxi tobacco-planting areas. [Method] 8 treatments were set to study the effects of the monoculture and mixed cropping of common vetch （Vicia gigantea Bge.）, perennial ryegrass （Lofium） and rapeseed （Brassica campestris L.） on physi- cal and chemical properties of soil and economic characters of flue-cured tobacco. [Result] （1） Green manure turnover can reduce soil bulk density by 1.08%-8.62%, and the effect of green manure mixed cropping pattern was the best. （2） Green manure turnover also can increase the soil nutrient, soil organic matter, total nitro- gen （N）, total phosphorus （P）, total potassium （K）, alkali-hydrolyzale N, rapidly available P and rapidly available K by 1.44%-6.10%, 0.01-0.12 g/kg, 1.89%- 11.32%, 0.12%-3.56%, 1.06%-11.76%, 0.04%-18.93% and 0.98%-23.12%, respec- tively, and the effect of the monoculture of common vetch was the best.（3） The overall change of soil pH was not obvious.（4）Green manure turnover can increase the yield and output of flue-cured tobacco, and the effect of the monoculture of common vetch was the best. [Conclusion] The monoculture of common vetch can be generalized in the dry land of Xiangxi tobacco-planting areas.

Analysis of Variation Characters and Prediction Model of Soil Temperature in Solar Greenhouse

[Objective] The aim was to study the soil temperature changes and its forecast model in greenhouse by solar heat. [Method] Annual and daily variation characters of soil temperature were analyzed in this paper by using the observation data of air temperature out of solar greenhouse and different layers soil temperature in it. The soil temperature (daily maximum, daily minimum and daily mean) forecasting models were also studied. Simulation and test were conducted to the forecast model of soil temperature in the greenhouse. [Result] The annual changes and daily changes of soil temperature of each layer in the greenhouse were in single peak curve. The lower layer temperature changes were smaller than the upper layer. The soil temperature of each layer within the greenhouse was closely related to the relevance of same type temperature outside the greenhouse of the day. Taking the average daily temperature, daily maximum temperature and daily lowest temperature of the day and the day before as forecast factors, soil temperature forecast model of different layer of same type within greenhouse was constructed. The simulation outcome of average daily temperature of each layer within the greenhouse was better than the simulation outcome of highest temperature of corresponding layer, worse than the simulation of lowest temperature of corresponding layer. The highest temperature of lower soil and daily temperature of soil were better than the upper layer. The simulated soil temperature was much more close to the observation when the observation was during 15-30 ℃. In other interval, it was lower than the observation. [Conclusion] The study offered theoretical reference for the growth environment of sunlight greenhouse plantation.

Ameliorate salinity effect through sulphur application and its effect on some soil and plant characters under different water quantities

The main objective of this work is to study the effect of sulphur application and irrigation water quantity on some soil properties of the calcareous soils and to limit the suitable concentration to obtain satisfactory yield of faba beab under saline conditions. The study area (Tamyia district, Fayoum Governorate, Egypt) is characterized by a hot and dry climate in general with annual rainfall average of 8 mm/year, whereas the evaporation rates average ranging between 3.5 to10 mm/day. Faba bean (Vicia faba L.) was sown at 18 November 2010 and harvested at 26 April 2011. Total water consumed during faba bean growing season were 623.7 and747.2 m3/ fed for 100% and 120% irrigation treatments with increasing ranged between 3.5% and 3.7% in same sequence. Results showed that values of soil EC, pH and CaCO3 was improved as a result of both irrigation and S treatments. The improvement resulted in a gradual reduction of the studied soil properties by about 10.3%, 3.2%;17.0% and 23.1%, 4.3%;11.3% comparing S treated plot relative to the control plot at 100 and 120% irrigation treatments. Application S improved water content under studied soil constant and these increases were 8.8%, 11.8%, 8.3% and 16.9% for SP, FC, WP and AW, respectively relative to the control plots. Irrigation 100% had a positive effect on the drainable pores% which increased by about 7.0% comparing with 120% irrigation treatments. While hydraulic conductivity increased by about 16.4% and percentage of increase drainable pores was 14.0% and 21.4% for 100% and 120% irrigation treatments comparing 3rd layer with the 1st one, respectively. Increasing irrigation water from 100% to 120% resulted increasing in the studied macronutrients, N, P and K, by about 80.8%, 144.9% and 72.9%, respectively;while they increased in plant by about 118.8%, 132.8% and 62.2% as compared with the control one, respectively as a result of S application. Results showed that Na, Cl and Na/K ratio that increasing irrigation water caused increase by 2.02%, 11.11% for Na and Cl, while reduction in the ratio between Na and K was observed with value –15.7% as compared 120 with 100% irrigation treatments. S application cause slightly increases in Na content (3.55%) and moderately increases with Cl (34.38%), which led to decrease Na:K ratio by about 39.4%. Increasing irrigation water by 20%resulted in a gradual increase of both yield and water use efficiency (WUE) of faba bean plants compared with the control plants. Irrigation treatments significantly decreased the contents of proline in dry weight seed of faba bean gradually as a result of increase irrigation quantity (from 100% to 120%) and the reduction was 9.7%. While S addition decreased proline by about 15.9%. According to the interaction effect between irrigation and S application treatments, S improved proline content by about 20.4% and 11.2% relative to the control treatments under 100% and 120% irrigation treatments, respectively %.

Optimal Interpolation and Kriging Mapping of Soil Characters in Glacial Moraine Landscapes

The objective of this research is to analyze optimal interpolation and Kriging mapping of soil characters in Glacial Moraine Landscapes. The research site is located in sloping landscapes, Kuehren, North Germany. The survey method was detailed using maps with scales of 1：5,000. Soil sampling was performed by soil pits and borings and completely analyzed in laboratory. Collected data were evaluated by Geostatistics program for spatial soil variability analyses. All maps （produced by Kriging interpolation） picture redistribution of soil nutrients and soil fractions and all map isolines run in similar directions according to landscape nets. The position in the landscape is responsible for increased soil variability. Soil variability becomes higher with decreasing elevation; this means it increases from hilltops to lower slopes. All observed soil characters show relationships to the soil variability. This variability system is caused by convex depressions and hedgerows （Knicks） function as barriers for the redistribution of transported material and offsite sedimentation. Therefore fluxes can be assessed by soil gain and loss balances.

Variogram Analyses of Soil Characters in Glacial Moraine Landscapes

The objective of this research is to analyze variogram analyses of soil characters in Glacial Moraine Landscapes. The research site is located in sloping landscapes, Kuehren, North Germany. The survey method was detailed using maps with scales of 1：5,000. Soil sampling was performed by soil pits and borings and completely analyzed in laboratory. Collected data were evaluated by geostatistics program for spatial soil variability analyses. The variogram models show that spatial soil variability ranges between 70-120 m （mean： 85 m）. Effective distances of sampling are calculated at around 50 m. The range values of soil characters are proportional with the range of elevation （range： 70 m, effective distance： 40 m）. The relief determines mainly the spatial variability of soil characters.

Effects of rainfall regime and its character indices on soil loss at loessial hillslope with ephemeral gully

Understanding the relationship between hillslope soil loss with ephemeral gully and rainfall regime is important for soil loss prediction and erosion control. Based on 12-year field observation data, this paper quantified the rainfall regime impacts on soil loss at loessial hillslope with ephemeral gully. According to three rainfall parameters including precipitation （P）, rainfall duration （t）, and maximum 30-minute rainfall intensity （I30）, 115 rainfall events were classified by using K-mean clustering method and Discriminant Analysis. The results showed that 115 rainfall events could be divided into three rainfall regimes. Rainfall Regime 1 （RR1） had large I30 values with low precipitation and short duration, while the three rainfall parameters of Rainfall Regime 3 （RR3） were inversely different compared with those of RR1; for Rainfall Regime 2 （RR2）, the precipitation, duration and Iso values were all between those of RR1 and RR3. Compared with RR2 and RR3, RR1 was the dominant rainfall regime for causing soil loss at the loessial hillslope with ephemeral gully, especially for causing extreme soil loss events. PI30 （Product of P and Izo） was selected as the key index of rainfall characteristics to fit soil loss equations. Two sets of linear regression equations between soil loss and Plzo with and without rainfall regime classification were fitted. Compared with the equation without rainfall regime classification, the cross validation results of the equations with rainfall regime classification was satisfactory. These results indicated that rainfall regime classification could not only depict rainfall characteristics precisely, but also improve soil loss equation prediction accuracy at loessial hillslope with ephemeral gully.

椰糠型生态保育基质栽培对辣椒品质及产量的影响

以‘甘科4号’辣椒为试材,以当地常规栽培作为对照(CK),采用温室大棚栽培的试验方法,研究椰糠、风沙土、人造泥炭、有机肥配比分别为5∶2∶1∶3(T1)、4∶3∶1∶3(T2)、3.5∶3.5∶1∶3(T3)、3∶4∶1∶3(T4)、2∶5∶1∶3(T5)、1∶6∶1∶3(T6)、0∶7∶1∶3(T7)复混形成的模块化生态保育基质对辣椒生长特性及产量的影响,以期为探索西部荒漠戈壁工业化土壤改良及特色生态农业发展提供新路径。结果表明:不同生育期下,T2~T5处理可促进辣椒长势(株高、茎粗、株幅),根系、品质和产量亦显著提高,且各项指标均随椰糠含量增加呈现先增大后降低的趋势;相较CK,T5处理下单株结果数和单株产量分别增加了9.47%、19.65%。利用VIKOR法对各处理的品质及产量进行综合评价显示,T5处理下辣椒品质及产量最优,利益比率最小,为0.019。研究结果进一步证明椰糠型生态保育基质(椰糠含量占比30%~55%)适合荒漠化土地上的辣椒种植。

交通荷载下的软土复合地基道路工程性状研究

针对软土复合地基上道路工程在交通荷载作用下的沉降问题,以武夷新区快速通道道路工程软土复合地基处理段为研究对象,运用动态弹塑性有限元软件,模拟软土复合地基在交通荷载作用下的变形情况,分析软土的累积塑性应变和软土复合地基的累积沉降变化特征。研究结果表明:随着交通荷载循环加载次数的增加,不同压缩模量工况的软土累积塑性应变均呈现非线性增加,并呈现不断收敛的趋势;在相同的交通荷载循环加载次数条件下,随着软土压缩模量的不断增加,软土的累积塑性应变不断减小;随着交通荷载循环加载次数的不断增加,软土复合地基的累积沉降曲线呈现反“S”形变化规律,当加载次数大于1000次后,软土复合地基的累积沉降趋于收敛。研究成果可以为降低软土复合地基工后沉降提供理论支持和实践指导。

根系分隔方式对燕麦/豌豆间作地上生物量、土壤养分及根系性状的影响

为了解燕麦/豌豆间作系统中根系分隔对地上生物量和土壤养分的影响,本研究设燕麦单作、豌豆单作、燕麦豌豆间作不分隔、尼龙网分隔和塑料膜分隔共5个处理,分析了燕麦/豌豆间作后株高、地上生物量、土壤养分和根系性状的变化。结果表明,塑料膜分隔处理降低了燕麦株高和间作地上生物量,其土地当量比小于1,而尼龙网分隔、不分隔处理的土地当量比大于1,间作优势明显。塑料膜分隔处理的土壤有机质含量较尼龙网分隔和不分隔处理降低了14.75%~78.53%,有效磷含量降低了9.31%~29.73%,土壤全氮含量在拔节和开花期的根系分隔处理中无显著变化(P>0.05),灌浆期塑料膜分隔较尼龙网分隔和不分隔处理分别降低了22.16%和18.38%,成熟期不分隔处理较塑料膜分隔高10.83%(P<0.05)。对豌豆而言,塑料膜分隔处理的土壤有机质含量显著高于不分隔和尼龙网分隔。此外,不分隔处理的燕麦根长较尼龙网分隔、单作和塑料膜分隔分别增加了43.03%、59.02%和96.38%;根表面积分别增大了14.84%、30.20%和45.55%;根体积分别增加了17.37%、38.15%和106.15%。由此可见,燕麦/豌豆间作显著影响了作物的根系性状,使根系对土壤养分的竞争力发生了变化,从而影响了地上生物量;根系互作越紧密,燕麦和豌豆的地上生物量越高;根系无互作的塑料膜分隔导致燕麦根系生长较差,土壤养分含量较低,间作生物量较低。

模拟酸雨对烟田土壤酸化及烟草生长发育的影响

我国西南地区是全球酸沉降负荷最高的地区之一,为明确酸性降水给烟田生态系统产生的可能危害,在田间利用自动模拟酸雨监测仪,模拟自然降雨(CK,pH 6.3)、超纯水(T1,pH 6.8)和酸雨(T2,pH 3.5)3种条件,测定其对土壤酸化及阳离子特征、烟草长势、生物量及氮磷钾积累量的影响。结果表明:(1)与CK和T1相比,T2土壤pH显著降低且随时间推移各处理之间差异逐渐增大;T2土壤交换性酸及铝离子含量显著增加,CEC和盐基总量下降;(2)T2显著抑制烟草生长发育,显著降低烟株株高、茎围、有效叶数及叶片长、宽,CK的茎和叶生物量最高,T1的根生物量最高;(3)根中氮和钾的积累量均为T2最低;茎和叶中氮的积累量表现为T2>T1>CK,茎和叶中钾的积累量表现为CK>T2>T1;磷的积累量在不同部位中差异不大,整体表现为T2最低。可见pH 3.5的酸雨能导致土壤明显酸化,显著抑制烟株生长发育,应采取有效措施控制其发生危害。

碎石土细颗粒迁移特征及优先流形成路径

碎石土是一种非连续、非均质的结构性材料,由于内部含有大量碎石块,容易形成架空结构,使其内部形成复杂独特的渗流通道即优先流通道,碎石土优先流通道是包括水分运移和土体细颗粒迁移的复杂过程,但在研究其优先流路径时通常只考虑了水分的运移而忽略了细颗粒的迁移,颗粒迁移与通道形成密切相关。为此,对两种不同级配土柱(粗细颗粒连续级配和间断级配)分别进行饱和渗流-颗粒迁移试验,从细颗粒迁移的角度分析通道形成的时空发展规律。试验结果表明:细颗粒迁移一部分由于流失引起碎石土渗透性增大,另一部分由于重新沉积而堵塞局部孔隙,降低渗透性,两者作用结果最终加速优先流通道形成;连续级配的碎石土形成大面积交叉分布的管网状渗流通道,间断级配的碎石土则形成集中渗流通道;相同水力条件下,不同级配细颗粒迁移的空间分布特征不同,连续级配的碎石土细颗粒迁移不随空间位置的差异而发生变化,间断级配的碎石土细颗粒迁移随空间位置的差异而发生变化,两种级配下碎石土细颗粒主要流失量的粒径范围均在1~0.075 mm;不同水力梯度条件下,连续与间断级配试验细颗粒流失量均随水力梯度增加而增大,间断级配的碎石土破坏时水力梯度小于连续级配破坏时水力梯度,间断级配碎石土更容易发生破坏。研究成果为进一步揭示碎石土优先流形成机理提供试验依据。

蚯蚓粪不同比例替代化肥对红薯生长及土壤肥力的影响

探究蚯蚓粪不同比例替代化肥对红薯生长及土壤肥力状况的影响,为红薯种植时的化肥减施提供科学依据。采用田间试验,设置7个处理:不施肥(CK);600 kg/hm^(2)氮磷钾复合肥(0R);10%替代(氮素总量与0R处理相同的前提下,10%的化肥氮素由蚯蚓粪替代,10%R);20%替代(20%R);40%替代(40%R);60%替代(60%R);100%替代(100%R)。在红薯发根分枝结薯期(栽秧后40 d)、蔓薯并长期(栽秧后120 d)、收获期(栽秧后160 d)测定红薯的农艺性状和土壤养分含量,分析收获期的红薯产量和品质指标。结果显示,在3个时期,40%R处理的红薯农艺性状(主蔓长、茎粗、叶长×叶宽、单株地上部分鲜重)整体较好,其次是0R处理。红薯单位面积产量在40%R处理(33.65×10^(3)kg/hm^(2))和0R处理(31.51×10^(3)kg/hm^(2))中最高,显著高于CK、60%R和100%R处理(P<0.05)。随着蚯蚓粪替代化肥的比例增加,红薯块根中淀粉和可溶性蛋白含量呈先增加后减少的趋势,在40%R处理中达到最高;可溶性糖含量则呈现相反规律。在红薯整个生长期,0R处理土壤速效养分含量整体较高,40%R处理与之差异不显著,土壤有机质含量以20%R和40%R处理最高,分别为16.43和16.08 g/kg。通过相关性分析发现,土壤速效养分之间呈显著正相关,淀粉含量与可溶性糖含量呈显著负相关。通过偏最小二乘路径模型(PLS-PM)发现,土壤速效养分对红薯产量有显著的正向影响,对红薯品质的正向影响非常小,但可以通过显著影响红薯农艺性状间接影响红薯品质。综合来看,40%蚯蚓粪替代化肥能在保证红薯较高产量的同时提高红薯品质,且能有效提高土壤有机质含量,有利于土壤肥力的可持续性。

不同类型地膜对土壤水热和油菜产量的影响

为研究在膜侧种植条件下,不同类型地膜对耕作层土壤水热条件和油菜生长状况的影响,设置普通塑料白地膜、黑地膜以及液态地膜3种地膜覆盖处理,以不覆膜作为对照(CK),开展田间试验,综合分析地膜对土壤水热和油菜生长与产量的影响。结果表明,与CK相比,3种覆膜处理使油菜苗期和蕾苔期的土壤含水率分别增加0.49%~2.29%和7.60%~10.77%,其中黑地膜、白地膜处理在蕾苔期保水效果显著;油菜干物质量分别增加6.36%~38.36%和7.52%~88.44%,其中黑地膜增幅最大,白地膜次之,蕾苔期均与CK差异显著;3种地膜处理对油菜农艺性状均有促进效果,其中黑地膜表现最优,其株高、主序长度、一次有效分枝数、一次有效角果数、每果粒数分别较CK增加11.53%、18.34%、50.10%、46.46%、87.50%。黑地膜处理油菜的产量为2926.50kg·hm^(-2),分别较白地膜、液态地膜、CK显著增产34.67%、81.60%、87.55%。综上所述,在膜侧种植下,覆盖黑地膜具有较好的保水增产效果,可作为西南旱地油菜节水抗旱、绿色高产高效的栽培措施。以上结果为进一步优化和普及地膜覆盖油菜提供理论和技术支撑。

不同吸力下伊犁河谷原状非饱和黄土强度特性试验研究

西风带影响下的伊犁河谷黄土分布广泛,黄土滑坡等灾害十分发育。研究不同吸力下伊犁河谷的非饱和黄土抗剪强度及变形特性,对地质灾害防治具有重要意义。本研究以新疆伊犁河谷的原状黄土为研究对象,开展矿物成分分析和物理性质测试,并利用非饱和土应力-应变控制式三轴仪,对黄土的原状样进行了控制净围压和吸力为常数的固结不排水剪切试验,分析非饱和黄土的强度特性。研究结果表明:(1)在试验测定的基质吸力范围内,净围压越高,试样应力-应变曲线的硬化特征越明显,试样在剪切过程中基本表现为鼓胀变形;在高基质吸力条件下,应力-应变曲线趋向于软化型,试样易出现剪切破坏。(2)试样体应变的变化受净围压和基质吸力的影响。随净围压的增大,体应变趋向于剪缩状态;在较高的基质吸力条件下,体应变的峰值剪胀量越大,剪胀特征也越强。(3)基质吸力影响非饱和黄土的抗剪强度参数。试样黏聚力随基质吸力的增大,表现出良好的线性增长趋势。而试验中基质吸力对内摩擦角的影响程度相对较低,随基质吸力的增大,粉质黏土土样内摩擦角的增长速率逐渐减小至0,内摩擦角值趋于稳定;而粉土土样内摩擦角无明显变化。本研究可为伊犁河谷黄土滑坡等灾害的研究提供力学参数和理论依据。

不同绿肥品种、种植时间对烤烟农艺性状、产质量及植烟土壤化学成分的影响

为探索不同绿肥品种与种植时间对植烟土壤化学成分及烤烟产质量的影响,分别在昭阳区布嘎回族乡、苏家院镇开展了小面积同田对比试验,共设置9个处理:种植光叶紫花苕同田冬闲对照(G_(CK))、8月5日播种光叶紫花苕(G_(0))、8月20日播种光叶紫花苕(G_(15))、种植黑麦草同田冬闲对照(H_(CK))、8月5日播种黑麦草(H_(0))、8月20日播种黑麦草(H_(15))、种植肥田萝卜同田冬闲对照(F_(CK))、8月5日播种肥田萝卜(F_(0))、8月20日播种肥田萝卜(F_(15))。结果表明:种植光叶紫花苕、黑麦草和肥田萝卜3种绿肥品种并翻压还田均对烤烟田间农艺性状和经济性状具有较好的改善作用,对植烟土壤的化学成分也具有一定的调控作用;光叶紫花苕和黑麦草在当地8月中旬末播种,下茬烤烟移栽前90 d内全部翻压还田对烤烟经济性状的提升效果较好,肥田萝卜在当地8月初播种,下茬烤烟移栽前90 d内全部翻压还田对烤烟经济性状的提升效果较好。

不同棉花高粱间作模式下土壤养分、棉花农艺性状及产量的研究

为了充分利用土地自然资源,探究绿色高产高效的棉花高粱间作模式,在山东省滨州市以‘冀梁2号’和‘鲁6269’为实验材料,设置4个间作模式处理,分析不同间作模式对棉花农艺性状、土壤养分含量、产量构成要素、产量以及经济效益的影响。结果表明,棉花高粱间作较棉花单作,棉花株高、果枝数、成铃数均显著提高,皮棉产量提高了0.73%~6.13%,纤维品质略微降低,有效提高土壤速效养分含量。3种间作模式中,4行棉花间作4行高粱模式下产量和经济效益表现最好,较棉花单作皮棉产量提高6.13%,经济效益增收13.79%,可作为山东地区棉花高粱间作模式的最佳行距配置。

平面SV波入射下地上建筑群-地铁隧道群动力相互作用研究

该研究采用一种高精度间接边界元方法(indirect boundary element method, IBEM),研究了平面SV波入射下地上建筑群-地铁隧道群的动力相互作用问题。研究表明:“建筑群-隧道群”系统存在显著的动力相互作用,其规律与入射波性质、建筑物和隧道数量排布等因素密切相关。通过对比不同建筑物数量对隧道动力响应的影响,能够发现:低频波作用下,建筑物对下穿隧道的动力响应有放大作用,而高频波作用下则会削弱隧道的动力响应,最多可以降低37.5%左右。从频域分析中可以看出:隧道对地震波有较强的屏蔽作用,从而降低了其上建筑群的地震响应。建筑群的存在降低了各个单体建筑的动力响应,但在高频波作用时位于建筑群来波一侧的建筑会产生较大的动力响应。该研究成果可为城市建筑群-地铁隧道群的动力相互作用分析以及地上建筑和地铁隧道的抗震设计提供理论依据。

喷施叶面钾肥对典型偏酸植烟土壤理化性质及烤后烟叶质量的影响

【目的】探明喷施叶面钾肥对植烟土壤理化性质及烤后烟叶质量的影响,为烤烟增钾和叶面钾肥施用提供技术支撑。【方法】以云烟121为研究对象,在典型偏酸土壤植烟区设置喷施清水(K_(0),对照)、腐殖酸钾(K_(1))、磷酸二氢钾(K_(2))、水溶性硫酸钾(K_(3))等4个处理开展试验,调查分析不同处理下烤烟的农艺性状、土壤理化性质、烤后烟叶经济性状和化学成分。【结果】喷施叶面钾肥可有效促进烟株中后期生长发育,改善烟株农艺性状,同时显著增强烤烟对普通花叶病的抗病性,K_(3)表现较优,发病率和病情指数分别较K_(0)降低52.54%和57.12%。与K_(0)相比,叶面钾肥处理可一定程度改善土壤理化性质,显著提高土壤速效养分含量。喷施叶面钾肥可促进烤烟增产增收,其中,K_(3)效果最显著,产量、产值和中上等烟比例分别较K_(0)升高7.21%、14.42%和6.23%。喷施叶面钾肥可有效改善中、下部烟叶化学成分,促进化学成分更协调,其中,增钾降氯效果最显著,且K_(1)和K_(3)效果较优,与K_(0)相比,中部叶钾分别升高43.75%和30.21%,氯分别降低61.54%和46.15%;下部叶钾分别升高17.48%和22.36%,氯分别降低22.22%和8.89%。【结论】喷施叶面钾肥可有效促进烤烟生长发育,增强烤烟抗病性,一定程度改善土壤理化状况,促进烤烟产质量提高,使中、下部烟叶钾含量增加、氯含量降低,其中,以水溶性硫酸钾效果最好。建议偏酸土壤植烟区烤烟在常规施肥基础上喷施水溶性硫酸钾,以达到烤烟增钾降氯的目的。

填埋龄期及压实度对垃圾腐殖土力学性质的影响

垃圾腐殖土的力学特性参数对其在岩土工程中的再利用具有重要意义。以填埋场现场取回的腐殖土为对象,基于饱和渗透性试验、无侧限抗压强度试验、直接剪切试验和固结压缩试验,分析了填埋龄期和压实度对压实腐殖土试样力学特性的影响规律,并探讨了其影响机制。结果表明,压实腐殖土饱和渗透系数处于10^(-5)~10^(-7)cm/s数量级范围内,且随着填埋龄期和压实度的增大,饱和渗透系数均减小并趋于稳定值;填埋龄期和压实度对压实腐殖土的力学性质影响显著,无侧限抗压强度、弹性模量、黏聚力和压缩模量整体上均随填埋龄期和压实度的增大而增大,而压缩系数随填埋龄期和压实度的增大而减小。以上成果为垃圾腐殖土再利用提供了关键理论支撑。