不同种植年限番茄大棚土壤理化性质的演变—— 以山东海阳地区为例

为了解山东省海阳地区蔬菜大棚土壤理化性质变化情况,测定了该地区150个不同种植年限(1～17年)番茄大棚土样的理化指标。结果得出,随着种植年限的增加,土壤体积质量(容重)逐渐降低但在种植11年后略微增加。土壤pH在17年间降低了25%,酸化程度日益严重。土壤有机碳含量在种植1～10年间增加了86.8%,但在之后的7年降低了69.7%。全氮的含量在种植1～9年间升高了1.41倍,但在之后的8年降低了52.3%。土壤碱解氮含量在种植1～8年间增加了79.5%,而在之后的9年降低了41.8%。土壤速效磷含量在种植1～9年增加了38.6倍,在之后8年又降低了68.9%。土壤速效钾含量在种植1～9年间增加了4.4倍,但在之后的8年间降低了77.7%。     

不同种植年限黄瓜温室土壤线虫群落结构及多样性的比较

【目的】针对土壤连作障碍问题,以土壤线虫群落结构和多样性为研究重点,分析不同种植年限土壤生态系统间的差异,进而探讨不同种植年限温室土壤的健康状况。 【方法】采集 8 年、10 年、13 年和 16 年温室黄瓜土壤,以1年露地土壤为对照,采用线虫形态学鉴定方法,分析不同种植年限土壤线虫群落结构及多样性的变化规律。 【结果】不同种植年限共观测到土壤线虫属 21 个,全部为优势属和常见属;线虫总数和植物寄生线虫数量在不同种植年限的分布依次为 10 年 > 16 年 > 13 年 > 8 年 > 1 年,线虫总数种植年限之间差异显著,范围为每 100 g 干土 61～437 条;线虫群落生态指数对种植年限有不同的响应,土壤线虫群落多样性指数 H′ 在不同种植年限土壤中的分布为 16 年 > 13 年 > 1 年 > 8 年 > 10 年,均匀度指数 J 为 13 年 > 16 年 > 1 年 > 8 年 > 10 年,而优势度指数 λ 的分布则为 10 年 > 16 年 > 13 年 > 8 年 > 1 年,5 种不同种植年限土壤的 NCR 指数在 0.6～9.8 之间,WI 分布为 1 年 > 8 年 > 13 年 > 16 年 > 10 年;线虫成熟指数 MI 在种植 16 年的温室土壤中最小,相反 PPI/MI 值则在种植 16 年的土壤中最大;丰富度指数 SR 随种植年限呈先升高后降低,10 年的最低;线虫区系分布结果显示,除种植 10 年黄瓜土壤的样点落在第 Ⅳ 象限外,其余种植年限黄瓜土壤的样点均落在第 Ⅰ 象限。 【结论】综合分析得出,连续种植会使土壤变得贫瘠,健康状况变差,受干扰程度变大,种植 10 年土壤线虫多样性、稳定性最差,土壤环境已受胁迫。     

Degradation and persistence of rotenone in soils and influence of temperature variations

The persistence and degradation of rotenone and its primary degradation product 12a beta-hydroxyrotenone in soils were determined under standardized laboratory conditions in the dark at 20 or 10 degrees C and at 40% of water holding capacity. Degradation experiments were carried out on two types of soil collected in southern Italy, a silt clay loam (SCL) and a loamy soil (L). A kinetic model was developed to describe degradation rates of rotenone, taking into account the production, retention, and degradation of the main metabolites. The DT50 values of rotenone and 12a beta-hydroxyrotenone, were 8 and 52 days in SCL soil, and 5 and 23 days in L soil at 20 degrees C, respectively. However, at 10 degrees C a tendency for slower degradation of rotenone and 12a beta-hydroxyrotenone was observed (25 and 118 days in SCL and 21 and 35 days in L soils, respectively). The differences were significant for most data sets. Temperature had a strong effect on degradation; a 10 degrees C increase in temperature resulted in a decrease in the DT50 value by a factor of 3.1 and 2.2 in SCL and of 4.2 and 1.4 in L soils for both rotenone and 12a beta-hydroxyrotenone, respectively. Results show that the degradation rates of both rotenone and 12a beta-hydroxyrotenone were greatly affected by temperature changes and soil physicochemical properties. The degradation reaction fits the two compartment or the multiple compartment model pathways better, which clearly indicates a rather complex rotenone degradation process in soils. Results provide further insights on the rates and the mechanisms of rotenone degradation in soils, aiming to more clearly describe the degradation pathway of chemical residues in the environment.     

A combined penetrometer and surface relief meter for studying drill coulter performance

A miniature penetrometer which measures soil strength in a vertical section across a drill line is described. It has a cone diameter of 3.6 mm and a range and resolution of 0–5000 and 5.4 kPa respectively. Data are recorded directly on to a portable digital tape logger which interfaces directly with a microcomputer for data analysis. The use of a horizontal reference height, rather than the soil, enables measurement of the soil surface relief. Results are presented showing the mean soil strength in a vertical section (200 mm wide by 130 mm deep) in drill lines in autumn and spring cultivated soil, with a horizontal and vertical resolution of 10 and 3 mm respectively.     

中国农业工程教育发展的新阶段——1978～1989

中国农业工程教育的发展经历了三个阶段。1949年前是农业工程教育的萌芽阶段,首次将农业工程课程编(纳)入高等学校教程是在1932年,农业工程的两个系分别于1947、1948年在中央大学、南京大学成立。新中国成立以后,农业工程教育在农业机械化技术的基础上迅速发展。1949年至1978年,农业工程专业的大学毕业生大约有2.5万名,中专毕业生6万名,他们中的大多数来自农业机械系。自1979年以来,我国农业工程教育进入了新的发展阶段,拓宽了高等院校,中等技术专业学校的农业工程专业范围。本文还讨论了中国农业工程教育发展过程中存在的一些问题。     

两株抗铜细菌的筛选、鉴定及对碳酸铜的溶解作用

本研究从长期受铜污染的铜矿废弃地土壤中分离得到两株对重金属铜具有较强抗性的菌株F16a和Fw17a。对菌株形态、生理生化特性及其16S rDNA系统进化进行分析,将F16a鉴定为肠杆菌属(Enterobacter),Fw17a鉴定为假单胞菌属(Pseudomona)。F16a和Fw17a对氨苄青霉素、头孢他啶均有抗性;此外,Fw17a还对氯霉素、四环素及低浓度的卡那霉素具有抗性。在有氮培养基(含500 mg/L CuCO3)液体培养48 h后,F16a使培养基上清液中铜浓度增加了300%左右;相反,Fw17a使培养基上清液中铜浓度降低了60%左右。     

Effect of shading on accumulation of flavonoid compounds in (Vitis vinifera L.) pinot noir fruit and extraction in a model system

Accumulation and compositional changes of flavonols, proanthocyanidins, and anthocyanins were measured in Vitis vinifera L. cv. Pinot noir in shaded and exposed treatments. In addition, extraction of these compounds into a model wine solution was measured. The study was conducted in a commercial vineyard within a uniform zone of relatively low vigor vines. Light exclusion boxes were installed on pairs of clusters on the same shoot (shaded treatment), and a second set of clusters on an adjacent shoot were labeled as the exposed treatment. Fruit samples were harvested at the onset of ripening (véraison) and at commercial harvest. Cluster shading resulted in a substantial decrease in mg/berry accumulation of flavonols and skin proanthocyanidins and minimal differences in anthocyanins. In analyzing seed proanthocyanidins by phloroglucinolysis, shaded and exposed treatments were similar at véraison; however, by harvest, the shaded treatment had higher extension and terminal subunits (nmol/seed) as compared to the exposed treatment. For skin proanthocyanidins, shaded fruit was lower for all subunits (nmol/berry) at both véraison and harvest. Shading caused an increase in the proportion of (-)-epicatechin and a decrease in (-)-epigallocatechin at harvest in skin extension subunits. Seed proanthocyanidins in shaded fruit contained a lower proportion of (+)-catechin and a higher proportion of (-)-epicatechin-3-O-gallate in extension subunits and a lower proportion of (+)-catechin and (-)-epicatechin-3-O-gallate and a higher proportion of (-)-epicatechin in terminal subunits. For anthocyanins, the shaded treatment had a proportional reduction in delphinidin, cyanidin, petunidin, and malvidin and a large increase in peonidin glucosides. The model extractions from the two treatments paralleled differences in the fruit with a lower concentration of flavonols, anthocyanins, and proanthocyanidins in the shaded treatment. The skin proanthocyanidin percent extraction was found to be approximately 17% higher in the exposed model extraction than the shaded treatment.     

Two- and multi-step annealing of cereal starches in relation to gelatinization

Two- and multi-step annealing experiments were designed to determine how much gelatinization temperature of waxy rice, waxy barley, and wheat starches could be increased without causing a decrease in gelatinization enthalpy or a decline in X-ray crystallinity. A mixture of starch and excess water was heated in a differential scanning calorimeter (DSC) pan to a specific temperature and maintained there for 0.5-48 h. The experimental approach was first to anneal a starch at a low temperature so that the gelatinization temperature of the starch was increased without causing a decrease in gelatinization enthalpy. The annealing temperature was then raised, but still was kept below the onset gelatinization temperature of the previously annealed starch. When a second- or third-step annealing temperature was high enough, it caused a decrease in crystallinity, even though the holding temperature remained below the onset gelatinization temperature of the previously annealed starch. These results support that gelatinization is a nonequilibrium process and that dissociation of double helices is driven by the swelling of amorphous regions. Small-scale starch slurry annealing was also performed and confirmed the annealing results conducted in DSC pans. A three-phase model of a starch granule, a mobile amorphous phase, a rigid amorphous phase, and a crystalline phase, was used to interpret the annealing results. Annealing seems to be an interplay between a more efficient packing of crystallites in starch granules and swelling of plasticized amorphous regions. There is always a temperature ceiling that can be used to anneal a starch without causing a decrease in crystallinity. That temperature ceiling is starch-specific, dependent on the structure of a starch, and is lower than the original onset gelatinization of a starch.     

Strengths of a densipan,humus-pan and clay-pan in a Spodosol developed under kauri (Agathis australis) and the implications for soil classification

Three hard layers have formed in a Spodosol developed on aeolian coastal sands under the influence of litter from kauri (Agathis australis). A densipan in the albic horizon and a humus-pan in the spodic horizon slaked in water whereas a clay-pan in a buried soil only softened in 1 M HCl. Blocks sawn from these three pans showed a maximum of unconfined compressive strength in the humus-pan.Specimens made from remoulded pan materials with minimum compaction developed only a proportion of the original strength. Greater compaction enhanced the strength of all three materials. Raising the pH during remoulding caused a marked increase in strength, but above pH 10.5 all the pan materials lost strength when silicate was solubilised from surfaces of clay and quartz particles.Scanning electron micrographs showed that the densipan was a close-fit configuration of sand- and silt-sized quartz particles that attained a high density without cementation of particles. In the humus-pan organic matter bridged across a third of the surfaces of the quartz particles and prevented a close-fit configuration. The clay-pan below the spodic horizon had all its particles thickly coated with clay and humus and these were aggregated into an open-fit arrangement of lower density.According to Soil Taxonomy procedures, the Te Kopuru sand lies within the Aquod sub-group of Spodosols. In the absence of a non-slaking duripan it was the presence of a fragipan below the spodic horizon that directed the soil into being a Fragiaquod. It is the densipan in the albic horizon above the spodic horizon, however, that controls plant roots and cannot be ignored in soil classification. We suggest that a new great group, Densiaquod, be recognized for these soils.     

基于SPEI的中国西北地区气象干旱变化趋势分析

中国西北地区深居欧亚大陆腹地,是同纬度最干旱的地区之一,如果持续干旱,将对该地区社会经济发展产生严重的影响。因此,深入研究西北地区的干旱特征,为制定改善生态环境,促进西北经济发展有着重要的意义。标准化降水蒸散指数(SPEI)将温度对蒸散的影响融合在内,是全球气候变暖背景下研究干旱的新理想指标。采用1959-2011年西北地区149个具有代表性的气象站点的资料,对西北地区近53 a干旱时空变化进行分析。结果表明,西北地区普遍存在干旱现象。从年际变化来看,该区呈变干趋势,1996年发生突变。从季节的变化来看,春、夏、秋明显变干,冬季有变湿趋势,变湿趋势不明显。春、夏、秋季发生突变,冬季突变不明显。从空间变化来看,春、夏秋大部分地区呈变干趋势,冬季大部分呈变湿趋势。与年鉴资料对比的结果进一步证明SPEI指数在西北地区具有较好的适用性。     

Einfluß von konstantem und abnehmendem Nährstoffangebot auf Aufnahme und Verteilung von K,Ca und Mg bei Sonnenblumen

Influence on the uptake of K, Ca and Mg in sunflowers with a constant and a diminishing supply of nutrients. . In a model-test with sunflowers it was investigated how the K-, Ca- and Mg-content in the plants is reacting when (a) a nutrient solution maintained constantly at the same level is given as in a ?good soil”? with a constant supply of nutrients, compared to (b) a solution with diminishing as in a highly fertilized soil but which hardly supplies nutrients itself. It was shown that, if the offer of the nutrient was constant, the cation content in the leaves could be maintained at the same level (the relation of cations is also maintained at the same time). Contrary to this with a diminishing nutrient solution due to removal of nutrients out of the solution without replenishing nutrients and the differentiated nutrient translocation the result was a lesser and lesser content of the nutrients inside the plant and more evident changes in the relation of cations, even before the insufficient supply was noted in a decreasing crop. Only in the leaves the relation of cations was nearly constant (K:Ca:Mg = 6:3:1). From these results it can be concluded that, through a high single supply of nutrients the effect of a constant flow of nutrients from the soil to the plant concerning the mineral contents of the plant cannot be compensated.     

1961-2010年锡林郭勒盟气温和降水时空变化特征

[目的]分析内蒙古自治区锡林郭勒盟气温和降水量时空变化规律,为草原区环境演化提供科学支撑,同时也对气温和降水的短期预警提供依据。[方法]利用研究区境内15个气象站点1961—2010年的逐月平均气温和月降水资料,结合一元线性回归分析、趋势分析、M K突变检验以及M o rlet小波分析方法,分析近50 a来锡林郭勒地区气温和降水时空变化特征及周期。[结果]近50 a来锡林郭勒地区气温以0．44℃／10 a的速率呈显著上升趋势,其中冬季温度上升最明显;年均气温有较明显的突变特征,突变点出现在1991年,突变前后2个时段平均气温相差1．32℃;存在28,9和5 a的周期律,未来几年仍处于暖期。降水呈波动下降趋势,速率为3．9 mm／10 a ,夏季降水下降最明显;年降水量没有明显的突变点,存在25和7 a的震荡周期,未来几年仍处于少雨阶段。[结论]近50 a来锡林郭勒盟地区气候呈明显干旱化趋势。     

Water activity effects on geranyl acetate synthesis catalyzed by novozym in supercritical ethane and in supercritical carbon dioxide

The esterification reaction of geraniol with acetic acid catalyzed by Novozym was studied in supercritical ethane (sc-ethane) and in supercritical carbon dioxide (sc-CO(2)). Water activity (a(W)) had a very strong effect on enzyme activity, with reaction rates increasing up to a(W) = 0.25 and then decreasing for higher a(W). Salt hydrate pairs could not prevent changes in a(W) during the course of reaction but were able to control a(W) to some extent and had a beneficial effect on both initial rates of esterification and conversion in sc-ethane. The enzyme was more active in sc-ethane than in sc-CO(2), confirming the deleterious effect of the latter already observed with some enzymes. Temperatures between 40 and 60 degrees C did not have a strong effect on initial rates of esterification, although reaction progress declined considerably in that temperature range. For the mixture of 50 mM acetic acid plus 200 mM geraniol, 100% conversion was achieved at a reaction time of 10 h at 40 degrees C, 100 bar, an a(W) of incubation of 0.25, and a Novozym concentration of 0.55 mg cm(-)(3) in sc-ethane. Conversion was below 50% in sc-CO(2) at otherwise identical conditions. With an equimolar mixture of the two substrates (100 mM), 98% conversion was reached at 10 h of reaction in sc-ethane (73% conversion in sc-CO(2)).     

Physical properties and spatial distribution of the plowpan in different arable soils

The morphology, water-physical properties, and spatial distribution of plowpans were studied. The presence of a plowpan in the root layer is most reliably detected from the macro- and micromorphometric indices and a reliable decrease in the interaggregate porosity and in the range of active moisture. As a rule, the plowpan does not have a continuous character; its appearance in the soil profile depends on the soil texture and wetting and is usually confined to the lower and wetter mesorelief elements. Loamy and clay loamy soils are more liable to form a plowpan. The current farming system favors the propagation of overcompaction deep into the soil profile. The areas with a plowpan within plowed fields vary in a wide range. The main reasons for the unfavorable physical properties of the subplow layer in a plowland are the natural extenuation of the soil-forming processes in this layer, which is manifested in a poorer aggregation, and the residual soil deformation under the long-term pressure of heavy machines. It is suggested that the plowpan can be destroyed via deep chiseling with the use of precision agriculture technologies.     

珠江三角洲平原不同种植年限土壤铁氧化物特征研究

珠江三角洲平原具有上千年的围垦历史,其土壤发生演变过程深受人为作用影响,开展此区域不同种植年限土壤中铁氧化物形态特征和分布规律的研究,能够揭示人为耕种下土壤发生演变过程。以珠江三角洲平原不同种植年限的土壤剖面为对象,研究了滨海沉积物、河流冲积物和三角洲沉积物发育的土壤及黏粒中全铁、游离铁含量变化及其影响因素。结果表明:随着种植年限的增加,河流冲积物、三角洲沉积物发育土壤中游离铁(Fe_d)向土体下部淀积深度逐渐增加,黏粒中游离铁(Fe_(d(clay)))含量在水耕氧化还原层中呈减小趋势,而滨海沉积物发育的土壤Fe_d含量及淀积深度均有所减小。随着种植年限的增加,滨海沉积物发育的土壤全铁(Fe_t)和游离铁(Fe_d)在黏粒中的富集程度呈增大趋势,而河流冲积物、三角洲沉积物发育的土壤Fe_t和Fe_d富集程度逐渐减小。土壤Fe_d与Fe_t、黏粒游离铁(Fe_(d(clay)))与黏粒全铁(Fe_(t(clay)))均呈极显著正相关;全铁富集率(Fe_(t(clay))/Fe_t)、游离铁富集率(Fe_(d(clay))/Fe_d)均与Fe_(t(clay))、Fe_(d(clay))、黏粒铁游离度(Fe_(d(clay))/Fe_(t(clay)))呈极显著正相关,与Fe_t、Fe_d、土壤铁游离度(Fe_d/Fe_t)、黏粒含量呈极显著负相关,且Fe_(t(clay))/Fe_t与Fe_(d(clay))/Fe_d呈极显著正相关,表明土壤铁氧化物在黏粒中的富集以Fe_d为主,且铁氧化物的富集程度受土壤黏粒含量的影响。     

渠江流域降水时空分布特征

基于1961-2020年渠江流域13个气象站点降水数据,运用累积距平、Mann-Kendall检验、小波分析和Kriging插值等方法研究分析了流域降水量及暴雨事件的时空分布特征。结果表明:渠江流域60年年均降水量1 126.17 mm,年降水量整体呈缓慢上升趋势,降水倾向率为6.9 mm/10 a。年降水量波动剧烈,存在27年、15年的周期性变化。年均降水量呈现由西部向东北部递增的趋势,降水量高值区位于流域东北部万源地区,低值区位于西部巴中地区。年降水量倾向率呈现由西北部向东南部递增的趋势,东部及南部降水倾向率为10~15 mm/10 a。渠江流域降水呈季节性变化,春季、秋季降水量呈下降趋势,夏季、冬季降水量呈上升趋势。5年滑动平均数据表明,夏季降水倾向率为16.9 mm/10 a,秋季降水倾向率为-7.7 mm/10 a。季节降水量波动明显,突变点较多,春、夏、秋季突变点主要集中于1961-1980年和2010-2020年间,冬季突变点集中于1985-2005年间。渠江流域春、夏、秋、冬四季降水倾向率最高值分别位于流域南部、东北部、东南部和西部。渠江流域汛期暴雨年均日数为4.28日,暴雨日数整体呈上升趋势,60年内暴雨日数以0.21 d/10 a的速率增加。汛期暴雨日数年际波动明显,1965年、1983年、1984年呈显著增加趋势。汛期暴雨日数存在14年、21年的周期性变化。渠江流域多年平均暴雨日数呈现由西南部向东北部递增的趋势,流域南部达川地区的上升趋势最快,较流域整体上升趋势高0.15 d/10 a。     

用计算机模拟农药在土壤中的移动和降解

本文应用CALF模式,用计算机模拟杀螨剂NC13292在淤积粘壤土中的移动和降解并与田间的实际测定进行比较,结果表明:当仅用吸附系数进行模拟时,经过一段时间以后,模拟的农药移动速度往往大于田间实际移动速度.它暗示农药在土壤中的移动可能存在着两个过程.一是农药在土壤固相与土壤水相之间的分配过程.这一过程对于农药在土壤中的移动起主导作用.二是扩散过程.只有在团粒结构或粘性土壤中,特别是对于极性农药,这一过程才相当重要,在应用吸附系数的同时,再引入一个经验扩散比率常数(0.0125/天),则NC13292在该土壤中移动速度的模拟结果与田间实际测定非常接近.