Prediction of surface runoff and soil loss in southeastern Norway using the WEPP Hillslope model

Yearly and daily surface runoff and soil loss simulated by the WEPP Hillslope model v. 2002.7 were compared with measurements from two different soil erosion plot sites in southeastern Norway. The soil at Bjørnebekk (Bj) was a levelled silty clay loam (2% organic matter) and the soil at Syverud (Sy) was a loam (5% organic matter). The plots at Bj were 21 m long and 8 m wide, while the plots at Sy were 30 m long and 7 m wide. Slope at both sites was 13%. Four management systems for grain production were used: autumn ploughing (AP), winter crop rotation (WCR), autumn harrowing (AH) and spring ploughing (SP). Hydraulic conductivity and soil erosion parameters were determined using WEPP-recommended equations based on measured soil parameters. In general, the WEPP Hillslope model simulated fewer runoff events than measured for all management systems during 1990–1998. Runoff events in winter were seldom predicted and small events (<5 mm) were mostly missed. To use the WEPP Hillslope model on Norwegian soils, where major soil loss events from arable land occur during late autumn, winter and early spring, improvements in winter hydrology calculations are needed. In particular calculations of soil frost development and infiltration into frozen soil need to be improved. The WEPP-recommended soil erosion parameter equations were unsuitable for these two Norwegian soils, especially for levelled soil.     

Evaluating the efficiency of sampling methods in assessing soil macrofauna communities in arable systems

The soil fauna is often a neglected group in many large-scale studies of farmland biodiversity due to difficulties in extracting organisms efficiently from the soil. This study assesses the relative efficiency of the simple and cheap sampling method of handsorting against Berlese–Tullgren funnel and Winkler apparatus extraction. Soil cores were taken from grassy arable field margins and wheat fields in Cambridgeshire, UK, and the efficiencies of the three methods in assessing the abundances and species densities of soil macroinvertebrates were compared. Handsorting in most cases was as efficient at extracting the majority of the soil macrofauna as the Berlese–Tullgren funnel and Winkler bag methods, although it underestimated the species densities of the woodlice and adult beetles. There were no obvious biases among the three methods for the particular vegetation types sampled and no significant differences in the size distributions of the earthworms and beetles. Proportionally fewer damaged earthworms were recorded in larger (25 × 25 cm) soil cores when compared with smaller ones (15 × 15 cm). Handsorting has many benefits, including targeted extraction, minimum disturbance to the habitat and shorter sampling periods and may be the most appropriate method for studies of farmland biodiversity when a high number of soil cores need to be sampled.     

Improved phosphorus efficiency of three new wheat genotypes from CIMMYT in comparison with an older Mexican variety

In a field trial in Northwest Mexico, the phosphorus efficiency of three advanced bread wheat lines (Triticum aestivum L.) from CIMMYT were compared with an older Mexican variety Curinda, under irrigation, on an alkaline clay soil (3.7 mg Olsen-P kg^—1 soil) without (P-0) and with P-fertilisation (P-35; 35 kg P ha^—1). Dry matter, P-content, P-uptake of above ground biomass and root growth (root length densities in different soil depths) were measured at different growth stages, and the net P-uptake rates per unit root length calculated. All four genotypes responded positively to P-fertilisation. The three new genotypes showed significantly higher grain yields compared with the old variety Curinda, on the average, 54% and 42% higher at P-0 and P-35, respectively. The higher grain yield was mainly due to a larger number of kernels per ear, higher thousand kernel weight as well as a higher harvest index. The old variety Curinda had the same (P-0) or greater (P-35) number of spikes m^—2 than the new genotypes. In conclusion of this experiment, the three new genotypes could be classified as more P-efficient. The P-uptake at harvest averaged 35% and 24% more than the old variety Curinda at the P-0 and P-35 level, respectively. The improved P-efficiency was mainly due to a more efficient P-uptake. However, there were only small differences in P-utilisation efficiency (kg grain per kg P in shoots) between old and new varieties (8—11%). The differences in the root systems were more decisive in the P-0 treatment than with P-fertilisation. At low P, the improved P-uptake per ha of the advanced lines was due to a higher root length density especially after flowering, while at high P, a higher P-influx rate per unit root length played a more important role than the root length density. The superiority of the new genotypes at both P levels is obviously due to the good adaptation of their root system (root length density, uptake rate per unit root) to variable P availability in soil.     

杂交狼尾草厌氧发酵的物质与能量转化率分析

为了解厌氧发酵过程中的C、N元素流动状况以及物质和能量的转化利用效率,以杂交狼尾草为原料,采用中温(35±1)℃批式厌氧发酵工艺,研究了杂交狼尾草厌氧发酵制备沼气的产气性能,在此基础上结合物质流分析方法分析了发酵过程中C、N元素的分布情况以及物质与能量的转化率.研究结果表明:C/N 167和25下,杂交狼尾草鲜料的VS(挥发性固体)产气量分别为280.02和242.33 mL/g,其中CH4体积分数分别为59.96%和61.46%;C/N 137和25下,青贮料的VS产气量分别为327.02和295.43 mL/g,其中CH4体积分数分别为58.49%和61.05%;C元素的流向分布:沼气33.1%,发酵液8.0%,发酵渣58.9%;N元素主要流入剩余物中:发酵液69.4%,发酵渣30.7%.杂交狼尾草厌氧发酵制备沼气的物质转化率和能量转化率分别为42.1%和33.1%.该研究为能源草本植物的资源管理和厌氧能源化利用提供了理论依据.     

硅对向日葵水分利用效率的影响

以向日葵(Helianthus.annuus.L.cv.G101)为试验材料,研究了硅对营养液培养的向日葵生长和水分利用效率的影响。结果表明,施硅显著增加向日葵的水分利用效率,对向日葵生物量、叶面积的影响不大,却使最大展开叶的SPAD值显著增加;施硅显著降低了向日葵叶片背面的蒸腾速率以及叶片导度,而对叶片正面的蒸腾速率和叶片导度影响不大。同时,施硅向日葵木质部汁液的流速显著降低,体内硅含量增加。表明叶片蒸腾速率、叶片导度、木质部汁液流速的降低是硅提高向日葵水分利用效率的主要原因。     

负压灌溉提高紫叶生菜的水分利用效率和根际微生物多样性

【目的】针对目前设施农业中常用的灌溉方式容易造成土表水分蒸发和水肥流失,且不能按照作物所需自动供水供肥的现状,本研究探讨了负压灌溉提高紫叶生菜的产量和品质,以及水分利用效率和土壤微生物群落多样性的机理。【方法】在温室内进行盆栽试验,以紫叶生菜(Lactuca sativa L.)为试验材料,设置3个灌溉处理:常规灌溉、滴灌和负压灌溉。收获后,测定了紫叶生菜的产量,分析了品质(维生素C、可溶性糖、花青素和硝酸盐含量),植株的养分(氮、磷和钾)浓度和吸收量,监测了土壤水分含量动态的变化,计算了水分消耗量和水分利用效率,分析了根际土壤微生物的多样性指数和细菌在门分类上的群落结构组成。【结果】负压灌溉下显著提高紫叶生菜的产量和品质,负压灌溉比常规和滴灌处理的产量分别显著提高了68.1%和29.0%,也提高了维生素C、可溶性糖和花青素的含量,减少了硝酸盐含量。与常规灌溉相比负压灌溉显著提高了紫叶生菜氮、磷、钾的浓度和含量,分别提高13.0%、14.4%、38.4%和90.2%、92.6%、135.5%。紫叶生菜在负压灌溉下耗水量最少,为9900 cm3,比常规和滴灌处理分别减少了23.8%和23.8%;负压下水分利用效率比常规和滴灌分别显著提高了122.2%和70.5%。同时负压灌溉处理下动态的土壤含水量处于10.3%~11.3%之间,变异范围低于常规和滴灌处理9.2%~11.6%。通过高通量测序紫叶生菜根际土壤微生物群落发现,负压灌溉处理下微生物多样性指数最高,表现为OTU、Chao1和Shannon指标的数值显著高于常规和滴灌处理,其数值分别为1808、2437和8.48,分别比常规灌溉处理显著提高了15.2%、15.7%和3.16%。同时也改变了细菌在门分类水平上组成的相对丰度,在负压灌溉处理下比常规和滴灌处理分别提高了放线菌门(Actinobacteria),绿弯菌门(Chloroflexi),疣微菌门(Verrucomicrobia)和浮霉菌门(Planctomycetes)在细菌门分类上的相对丰度。【结论】本试验证明了负压灌溉系统通过土壤水肥平稳供应机制,实现了紫叶生菜高产优质且高效利用水分的目标。因此,负压灌溉系统相比常规和滴灌,显著提高了紫叶生菜的产量和品质、水分利用效率和根际微生物群落的多样性,为设施农业的可持续性发展提供科学依据。     

生长模型和15N示踪评价施肥处理对苹果树氮肥利用的影响

为提高果树氮肥利用率,探索一种简便易行的氮肥利用评价方法,该研究以田间5年生延长红（“长富2号”芽变品种）为研究对象,分别采用生长模型和15N示踪技术对比分析不施氮肥（CK）、常规高氮（N800,800 kg/hm2化肥氮）、优化减氮（N400,400 kg/hm2化肥氮）和有机无机配施（N200+O200,化肥氮和有机氮各200 kg/hm2）处理下苹果树对氮肥的吸收利用情况以及各器官氮素的分配特性的差异,结果表明：不同施肥处理对苹果的产量没有显著性的影响（31.7～37.3 t/hm2）;各施氮处理基于生长模型和15N示踪技术的果树氮肥利用率分别为13.13%～31.94%和11.64%～32.40%;基于生长模型,N400和N200+O200处理果树的氮肥利用率比N800处理高84.92%和143.26%;基于15N示踪技术,N200+O200处理的果树氮肥利用率比N800和N400高178.35%和69.28%;不同施肥处理对各器官氮素分配没有显著性的影响。两种评价方法对于果实和叶片的氮肥利用率、各器官氮素的分配情况分别存在显著差异（P<0.05）和极显著差异（P<0.01）,但对植株总体氮肥利用率的评价结果无显著差异,平均仅相差3.10%。基于本试验的研究结果可以得出,利用生长模型可以估算苹果树的氮肥利用率。研究结果可为农田管理措施改善以及果树氮肥利用率评价提供理论参考。     

鱼游泳能力对体长的响应及其在鱼道设计中的应用

为了探讨鱼类体长对游泳能力的影响并为鱼道水流的设计提供参考,该研究在封闭水槽中使用"递增流速法"测试了海南省某水利枢纽鱼道目标对象的游泳能力,并用Origin软件进行了数据统计分析,得到了试验鱼感应流速、临界游泳速度和爆发游泳速度的直线回归方程和Kaplan-Meier曲线.结果表明:1)随着试验鱼体长增大,相对感应流...     

Increased plant density with reduced nitrogen input can improve nitrogen use efficiency in winter wheat while maintaining grain yield

ABSTRACT

Plant density and nitrogen (N) input level have notable effects on root development, distribution in the soil profile, and in turn, N-uptake of winter wheat. Our study objectives were to identify whether a high yield can be maintained with a reduced N input by increasing plant density. Field studies were conducted during four successive seasons (2014–2015, 2015–2016, 2016–2017, and 2017–2018) using a widely planted cultivar, Tainong18. Two regimes of N fertilization (180 kg ha^?1 and 240 kg ha^?1) and three planting densities (135, 270, and 405 plants per m²) were used. Higher plant density led to increased root length density (RLD) and enhanced N uptake from the whole soil profile. The RLD in the soil profile at 0–1.2 m, 0–0.4 m, and 0.4–0.8 m decreased while in the 0.8–1.2 m layer it increased in response to reduced N input. The combined effects of higher plant density and lower N input resulted in reduced N uptake, a lower nitrogen nutrition index (NNI), unchanged grain yield, and improved N use efficiency. In conclusion, it is possible and sustainable to maintain a high wheat yield with reduced N input by increasing plant density.     

Chlorophyll meter readings,N leaf concentration and their relationship with N use efficiency in oregano

Plant-based diagnostic techniques such as chlorophyll meter (CM) readings and nitrogen (N) leaf concentration are used to determine the level of crop N nutrition, but research is limited on perennial crops and especially on aromatic and medicinal plants such as Greek oregano (Origanum vulgare spp. hirtum). The objectives of this study were to determine in a perennial crop species whether there is a relationship between the CM readings, N leaf concentration, and N use efficiency (NUE) and to use CM readings as a diagnostic tool for predicting dry matter yield in response to N fertilization. The CM readings varied across environments, growth stages, and fertilization treatments and were correlated with NUE. NUE was also affected by the environment, N fertilization, and interactions among these variables. This study provides new information about the effect of N application on CM readings, N leaf concentration, and NUE in a perennial crop such as oregano.     

基于SPA-VFS耦合模型的河套灌区灌溉用水效率分级

针对大型灌区用水效率分级评价问题,该研究构建河套灌区用水效率综合评价指标体系和指标分级标准,采用改进熵值法对评价指标赋权,将集对分析法(Set Pair Analysis theory,SPA)和可变模糊理论(Variable Fuzzy Set theory,SFS)结合,应用SPA-VFS耦合模型,进行河套灌区用水...     

中国省际耕地利用效率时空格局分异与机制分析

科学剖析省际耕地资源利用效率时空格局分异及机制,对推进省际耕地资源集约利用具有重要的理论及实践意义。该文以中国省域(除港、澳、台)作为研究案例区,从投入和产出2个维度构建指标体系,运用改进DEA(data envelopment analysis)模型测度1994—2012年中国省域单元耕地利用效率值;综合利用ESDA(exploratory spatial data analysis)关联模型、R/S(rescaled range analysis)分形模型等方法分析省际耕地利用效率时空格局分异特征,并通过Tobit回归模型揭示效率时空分异的驱动机制。结果表明:1994—2012年中国省际耕地利用效率DEA最优比例相对较小,空间表征出东部高、中西部低的分布格局;东部沿海、北部沿海、东北地区综合效率较高,呈上升发展趋势,技术效率与综合效率变化较相似,而规模效率呈现先上升后下降态势;全局上省际耕地利用效率呈现空间正自相关,以空间集聚为主要分布模式;局部上可划分4种类型:H-H(high-high)效率区、H-L(high-low)效率区、L-H(low-high)效率区、L-L(low-low)效率区,其中H-H效率区主要分布在长三角、京津地区,并逐渐向珠三角演化,而L-L效率区主要集聚在中国西北地区;未来省际耕地利用效率将表现出继续增长的分形特征,且增长高值区集聚在中国东部、北部沿海;经济发展水平、农业科技进步是影响效率空间分异的重要因素,自然环境条件是效率发展差异的基础因素,而农户自身特征也会对效率时空分异产生一定冲击;最后,从推动技术进步、调整产业结构、耕地整理流转、补偿激励机制等方面提出省际耕地集约利用政策建议。     

不同灌水处理条件下不同小麦品种氮素积累、分配与转移的差异

利用15N同位素示踪技术,研究了不同灌水处理条件下2个高产小麦品种吸收利用不同来源氮素的差异。结果表明:1)同一灌水条件下,泰山23(T23)植株氮素总积累量、来自肥料氮的量、来自土壤氮的量、肥料氮和土壤氮开花期在营养器官中的总积累量及成熟期在子粒中的积累量均显著高于山农664(S664)。2)泰山23底墒水+拔节水处理(W1)营养器官中积累的肥料氮向子粒的转移量显著高于底墒水+拔节水+开花水处理(W2),土壤氮的转移量W1与W2处理无显著差异;山农664营养器官中积累的肥料氮和土壤氮的转移量均为W2显著高于W1处理。3)泰山23的子粒蛋白质含量、灌溉效益和水分利用效率为W1显著高于W2处理,子粒产量、蛋白质产量和氮素利用效率在W1与W2处理间无显著差异;山农664的子粒产量和蛋白质产量为W2显著高于W1处理,子粒蛋白质含量、氮素利用效率、灌溉效益和水分利用效率在W1与W2处理间无显著差异。从子粒产量、蛋白质含量和氮素与水分利用效率等方面综合分析,W1和W2处理分别是泰山23和山农664高产高效的灌水方式。     

基于CFD的植物工厂圆形锯齿状水冷LED灯管降温效果模拟

为及时将LED灯管芯片产生的热量传导出去,提升LED灯的性能,延长其使用寿命,设计了一种圆形锯齿状水冷LED灯管,并通过计算流体力学(Computational Fluid Dynamics,CFD)软件构建水冷LED灯管模型,对其降温效果进行研究.在模型中将LED灯珠芯片设置为内热源,热流密度根据灯珠的数量和电光转化...     

LED光源红蓝光配比对生菜光合作用及能量利用效率的影响

为了提高植物光能及电能利用效率,降低植物工厂光源的投入产出比,该文从不同红蓝光配比(R/B)对生菜光合作用影响机理入手,分析不同R/B对生菜光能及电能利用效率的影响。以荧光灯处理(FL)作为对照,通过设置不同红蓝光配比(R/B)共7个处理进行试验,测定不同R/B下生菜的Ru Bis Co羧化速率和氧化速率、光合电子流分配以及叶氮分配。结果表明:1)当R/B≥8时,增大蓝光比例显著降低了总电子传递速率向参与光呼吸的光合电子流的分配,促进了叶氮向羧化系统和生物能学系统中的投入,提高了叶片的光合作用;2)当R/B≤8时,生菜电能利用效率(electric-energy use efficiency,EUE)和光能利用效率(light use efficiency,LUE)随着R/B增加而显著增大,R/B≥8处理间EUE无显著性差异,但R/B=12处理下LUE较R/B=8处理高12.5%。综上所述,在光强为200μmol/(m2·s)的红蓝LED植物工厂中,R/B为8是影响生菜光合作用、光能及电能利用效率的转折点;为保证生菜高效生产,以红蓝光配比不小于8为宜。     

高效回转式泵站拦污清污机研制

为提高拦污清污设备的可靠性和清污效率,对齿耙牵引链条采用滚轮凸轨行走方式和限位装置,避免脱轨,提高齿耙左右定位精度;在此基础上,优化栅条、耙齿和齿耙管断面形状,实现耙齿、齿耙与栅条精确紧密配合,减少栅条污物粘附与卡堵,切断拖拽的水草,避免清污初期由于栅前过多的水草造成耙齿和齿耙过载损坏;单孔较宽的拦污栅采用2～3片分体结构拦污栅架,便于栅体吊装检修和更换;采用侧边导污板和底部弧形前置栅,提高侧边和底部污物清污效率。应用结果表明,回转式拦污清污机通过结构改进,提高了运行可靠性和拦污清污效率,降低了设备故障率和维护成本,减小了拦污栅前后水位差,提高了泵站运行可靠性和效率,运行维护费用节省9%以上,清污效率提高30%以上,拦污栅体前后平均水位差由60 cm减小到10 cm以下,泵站运行费用减小8%左右。     

RZWQM2模型模拟地膜覆盖时间对棉田氮素迁移特征和氮肥利用效率的影响

[目的]地膜覆盖时间影响着棉田养分的迁移及氮素利用效率,我们尝试利用根区水质模型(root?zone water?quality?model-version?2,?RZWQM2)评估新疆绿洲棉田不同地膜覆盖时间下土壤氮素迁移特征和作物吸收利用率,为优化地膜覆盖方法提供理论依据.[方法]于2017—2018年在新疆进行了...     

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根据南丹县农业资源特点和农业种植结构现状，分析农业种植结构存在问题，提出农业种植结构调整与高产高效农业发展建议。     

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养分回收是植物养分利用策略的重要驱动力,可减少养分流失,降低其对环境的依赖性,对植物种群和群落稳定性、生态系统养分循环都具有重要的生态学意义。本文在收集北方山区(黄土高原、太行山区、京北山区)天然林、人工林等各种森林成熟叶片和凋落物氮、磷养分含量等资料的基础上,根据群落生活型和管理方式将各类森林进行归并,对其养分回收效率进行了综合评估。结果表明,各类森林植被通过成熟叶片和落叶中氮、磷含量计算得到的叶片氮、磷回收效率分别是24.5%~71.3%和18.1%~75.4%,均值分别是45.5%和47.4%。北方山区天然林和人工林成熟叶片的平均氮含量分别是11.6 g·kg~(-1)和21.6 g·kg~(-1),人工林成熟叶片氮含量显著高于天然林,养分在人工林生长过程中可能基本处于消耗状态。不同地区天然林与人工林叶片磷含量存在差异:太行山区天然林成熟叶片和枯落叶片磷含量显著高于人工林,而京北山区人工林成熟叶片磷含量较高,枯落叶片磷含量较低。灌木成熟和枯落叶片中氮含量显著高于乔木,而两者间磷含量无显著差异;灌木叶片氮回收效率高于乔木。通过3个地区的比较发现,京北山区树木叶片氮、磷回收效率分别是62.1%和67.8%,高于其他两个地区。相关分析表明,北方山区森林枯落叶片氮含量是影响叶片氮、磷回收效率的重要因子。通过对不同树种养分回收效率的比较发现,针叶树种养分回收效率大于阔叶树种,这说明在土壤养分贫瘠山区针叶树种的养分回收效率更高,更能适应这种贫瘠的土壤环境。在山区进行人工建植时,针叶树种高的养分利用效率应该被考虑进来。