不同林草植被覆盖度的水土保持效益及适宜植被覆盖度

以1954--2004年南小河沟流域水文气象观测资料及所布设的林地、草地径流场观测资料为数据源,进行坡面侵蚀强度与径流指标、降水指标、植被覆盖指标之间的定量分析。结果表明：林草植被措施减轻坡面侵蚀的作用明显;防治水土流失的林草植被覆盖度以40％～60％分界明显;从防治水土流失的角度出发,黄土高原沟壑区人工林地和草地建设的有效植被覆盖度应不小于60％和50％。     

Evaluation of an open portable chamber system for measuring cover crop water use in a vineyard and comparison with a mini-lysimeter approach

Cover crops are largely used in viticultural areas because of the many positive agronomic and environmental benefits they provide. However, there is insufficient data describing the amount of water they use. A portable chamber used as an open measurement system and its suitability to measure the cover crop evapotranspiration (E) in a vineyard are described in this study. The performance of the chamber was tested by a calibration experiment (R² = 0.97). The lowest air flow rate used (9.2 l s⁻¹) was found to be suitable to limit the chamber from overheating beyond 3.1 K above the outside temperature. Furthermore, an experiment was designed to compare the daily cover crop (Festuca arundinacea var. barfelix) water use measured by the chamber system with measurements using a mini-lysimeter (ML) method and with estimates using the FAO-56 PM equation (Eo). The experiment was carried out in one inter row of a vineyard over the course of 4 days following an irrigation event. Although the field experiment was limited to 4 days, the results obtained together with the calibration trials support the possibility of the chamber being a useful tool for measuring the cover crop E. The ability of the MLs to represent the water use of the cover crop in the rest of the vineyard was limited to the first two days of the experiment, after which time the soil water content inside the containers was significantly (p = 0.007, p = 0.03) lower than in the surrounding field.     

Compiling a field manual from overhead photographs for estimating crop residue cover

Abstract. A method is presented for compiling a manual for the estimation of crop residue cover in the field. The crop residue is a combination of standing stubble and the straw remaining on the ground after harvest. Field assessment of crop residue is important so that management decisions may be made in the field. Such decisions include selection of cultivation or sowing machinery, irrigation scheduling (for crusting materials), soil temperature control and grazing of crop residue. The manual consists of a graded set of colour photographs, taken from an overhead boom, and a sampling rate nomogram to determine the number of 1 m quadrats required in a given field to estimate the cover with a predetermined level of error. Two methods for calibration of the photographs are compared: (a) projection of slides onto a screen with manual counting, and (b) digital image analysis of the photographs. Image analysis is efficient, rapid and gives less error than counting from the projections because many more points are counted. The use of the manual in the field is described. It is an inexpensive piece of equipment for the field agronomist or farmer, and gives a reliable, rapid and semi-quantitative estimate of residue cover.     

Remote sensing of crop residue cover and soil tillage intensity

Management of plant litter or crop residues in agricultural fields is an important consideration for reducing soil erosion and increasing soil organic C. Current methods of quantifying crop residue cover are inadequate for characterizing the spatial variability of residue cover within fields or across large regions. Our objectives were to evaluate several spectral indices for measuring crop residue cover using satellite multispectral and hyperspectral data and to categorize soil tillage intensity in agricultural fields. Landsat Thematic Mapper (TM) and EO-1 Hyperion imaging spectrometer data were acquired over agricultural fields in central Iowa in May and June 2004. Crop residue cover was measured in corn (Zea mays L.) and soybean (Glycine max Merr.) fields using line-point transects. Spectral residue indices using Landsat TM bands were weakly related to crop residue cover. With the Hyperion data, crop residue cover was linearly related to the cellulose absorption index (CAI), which measures the relative intensity of cellulose and lignin absorption features near 2100 nm. Coefficients of determination (r²) for crop residue cover as a function of CAI were 0.85 for the May and 0.77 for the June Hyperion data. Three tillage intensity classes, corresponding to intensive (<15% residue cover), reduced (15–30% cover) and conservation (>30% cover) tillage, were correctly identified in 66–68% of fields. Classification accuracy increased to 80–82% for two classes, corresponding to conventional (intensive + reduced) and conservation tillage. By combining information on previous season's (2003) crop classification with crop residue cover after planting in 2004, an inventory of soil tillage intensity by previous crop type was generated for the whole Hyperion scene. Regional surveys of soil management practices that affect soil conservation and soil C dynamics are possible using advanced multispectral or hyperspectral imaging systems.     

耕作管理措施对残茬覆盖及其分解的影响

The effects of tillage methods on percent surface residue cover remaining and decomposition rates of crop residues were evaluated in this study. The line transect method was used to measure residue cover percentage on continuous corn (Zea mays L.) plots under no tillage (NT), conventional tillage (CT), chisel plow (CH), and disk tillage (DT). Samples of rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth) were used for residue decomposition study. Results showed that the percentage of residue cover remaining was significantly higher for NT than for CH and DT and that for CT was the lowest (< 10%). For the same tillage system, the percent residue cover remaining was significantly higher in the higher fertilizer N rate treatments relative to the lower fertilizer N treatments. Weight losses of rye and vetch residues followed a similar pattern under CT and DT, and they were significantly faster in CT and DT than in NT system. Also, the amounts of residue N remaining during the first 16 weeks were always higher under NT than under CT and DT.     

Remote sensing of crop residue cover and soil tillage intensity

Management of plant litter or crop residues in agricultural fields is an important consideration for reducing soil erosion and increasing soil organic C. Current methods of quantifying crop residue cover are inadequate for characterizing the spatial variability of residue cover within fields or across large regions. Our objectives were to evaluate several spectral indices for measuring crop residue cover using satellite multispectral and hyperspectral data and to categorize soil tillage intensity in agricultural fields. Landsat Thematic Mapper (TM) and EO-1 Hyperion imaging spectrometer data were acquired over agricultural fields in central Iowa in May and June 2004. Crop residue cover was measured in corn (Zea mays L.) and soybean (Glycine max Merr.) fields using line-point transects. Spectral residue indices using Landsat TM bands were weakly related to crop residue cover. With the Hyperion data, crop residue cover was linearly related to the cellulose absorption index (CAI), which measures the relative intensity of cellulose and lignin absorption features near 2100 nm. Coefficients of determination (r²) for crop residue cover as a function of CAI were 0.85 for the May and 0.77 for the June Hyperion data. Three tillage intensity classes, corresponding to intensive (<15% residue cover), reduced (15–30% cover) and conservation (>30% cover) tillage, were correctly identified in 66–68% of fields. Classification accuracy increased to 80–82% for two classes, corresponding to conventional (intensive + reduced) and conservation tillage. By combining information on previous season's (2003) crop classification with crop residue cover after planting in 2004, an inventory of soil tillage intensity by previous crop type was generated for the whole Hyperion scene. Regional surveys of soil management practices that affect soil conservation and soil C dynamics are possible using advanced multispectral or hyperspectral imaging systems.     

On-column partition cleanup of fatty extracts for organophosphate pesticide residue determination

A fast, single-step, and efficient partition between n-hexane and acetonitrile on ready-to-use, disposable mini-columns of Kieselghur-type material has been developed for the cleanup of fatty extracts for organophosphate (OP) pesticide residue determination by gas chromatography with flame photometric detection. Nine OP pesticides (diazinon, etrimfos, chlorpyrifos-methyl, pyrimiphos-methyl, chlorpyrifos, bromophos, bromophos-ethyl, malathion, fenitrothion) most commonly used for protection of stored cereals, oil seeds, and legumes were separated from up to 2.0 g lipidic material with recoveries between 80 and 107% at spiking levels ranging for the different compounds from 0.1 to 5.0 ppm.     

基于模拟Landsat-8 OLI数据的小麦秸秆覆盖度估算

田间秸秆作为农业生产过程中的重要物质,其覆盖度的遥感估算具有十分重要的意义。Landsat-8 OLI影像作为Landsat系列影像的最新数据产品,具有更精细的光谱特征,明确其在秸秆覆盖度估算中的表现具有重要的现实意义。该研究使用ASD Field Spec 4 Hi-Res地物光谱仪,以实测田间小麦秸秆光谱反射率为数据源,模拟Landsat-8 OLI、Landsat-5TM、Aster、Hyperion影像波段反射率,构建光谱指数,并建立小麦秸秆覆盖度估算模型,通过对比分析,评估Landsat-8OLI数据的估算能力。结果表明,基于Landsat-8 OLI1和OLI2波段构建的NDIOLI21指数模型估算结果最优,决定系数(coefficient of determination,R2)为0.60,均方根误差(root mean square error,RMSE)为9.56%,平均相对误差(mean relative error,MRE)为9.83%,优于Landsat-5 TM构建的光谱指数,且仅次于Aster构建的木质素-纤维素吸收指数(lignin cellulose absorption,LCA)和短波红外归一化差异秸秆指数(shortwave infrared normalized difference residue index,SINDRI)以及Hyperion构建的纤维素吸收指数(cellulose absorption index,CAI)。因此,波段更多、波段划分更加精细的Landsat-8OLI构建的光谱指数在小麦秸秆覆盖度估算方面达到了一定精度,具有良好的应用前景。     

基于HJ-1B数据的冬小麦留茬覆盖度遥感估算

作物茬作为农田生态系统的重要组成部分,影响着农田生态系统中的营养物质、碳、水和能量的流动与循环。建立了基于HJ-1B数据的冬小麦留茬覆盖度遥感估算模型,为区域作物留茬覆盖度遥感监测提供技术支撑。以山东禹城市冬小麦为例,分析了冬小麦留茬覆盖度与HJ-1B CCD数据各波段反射率、红外多光谱成像仪IRS数据的近红外和短波红外波段反射率及三种归一化光谱指数之间的相关关系,选取IRS归一化指数构建冬小麦留茬覆盖度光学估算模型。使用独立的地面观测数据对模型进行检验,模型估算的最大相对误差为24.96%,平均相对误差为9.28%,达到了一定精度。     

Study of an online molecularly imprinted solid phase extraction coupled to chemiluminescence sensor for the determination of trichlorfon in vegetables

This study reports a new online molecularly imprinted solid phase extraction coupled to chemiluminescence for the determination of trichlorfon. This molecularly imprinted polymer (MIP) was prepared through bulk polymerization, in which methacrylic acid (MAA) was used as the functional monomer and ethylene glycol dimethacrylate (EGDMA) as the cross-linker. This novel functionalized material was characterized by FT-IR spectra and adsorption, and it exhibited good recognition and selective ability and fast adsorption-desorption dynamics toward trichlorfon. The factors affecting preconcentration of the analytes and sensitivity of the method are discussed in detail. Under the optimal condition, the linear range of the calibration graph was between 0.02 and 1.0 ng L(-1), and the detection limit was 1 × 10(3) ng L(-1). The blank cucumber samples spiked with trichlorfon at three levels were extracted and determined by the presented method with recoveries ranging from 83.5 to 94.5%, and the results were correlated well with those obtained using gas chromatography. Moreover, this developed method was successfully applied to the quantitative detection of trichlorfon residues in leek samples.     

Evaluation of selected enzymes for thiamine determination

Seven commercially available enzymes were studied for suitability as substitutes in the AOAC thiamine determination, because the enzyme Takadiastase used in the method has not been available since 1976, and alternative enzymes were likewise unavailable or unsuitable for releasing thiamine from its phosphate esters. Four factors (substrate ester, enzyme level, time/temperature, and pH) at 2 levels were studied in a 2(4) factorial arrangement of treatments. Data were expressed in terms of mean percentage conversion (MPC) and were statistically evaluated by analysis of variance. Significant main effects and any interactions among treatments were calculated. Takadiastase and alpha-amylase (Miles) with MPCs of 101 and 102, respectively, appeared effective in dephosphorylation within method parameters. Potato phosphatase appeared marginally suitable. Wheat germ phosphatase, alpha-amylase (Sigma), Mylase 100, and Clarase 40,000 were judged unacceptable as enzyme substitutes.     

残茬覆盖对寒地旱作区土壤温度的影响

在黑龙江省西部干旱区建立不同残茬覆盖对土壤温度影响试验区,采用WQG-16.-21-61℃型曲管地温表分别测定土壤地表下5、10、15、20 cm各层温度,确定不同残茬覆盖对北方寒地旱作区土壤温度的影响规律。试验结果表明,残茬覆盖对土壤温度有明显的调节作用,5、10、15、20 cm各层有覆盖相对于无覆盖分别增温1.5～2.1℃、0.9～1.2℃、0.2～0.9、0.4～0.8℃,随着土壤层的加深,覆盖对土壤温度的调节作用越来越小。4月20日至6月15日前后,随着覆盖量的增加,土壤温度开始升高,但覆盖量增加到一定程度后,土壤温度将下降,在6月20日以后,随着覆盖量的增加,土壤温度逐渐降低,其中30%覆盖相对于无覆盖,降低1.1～1.5℃,50%～80%覆盖降低2～3.6℃,而表土层降低幅度最大,沿深度方向幅度越来越小。因此,在北方寒地农业区,考虑土壤温度这个影响因素时,完全可以进行残茬覆盖,覆盖的范围应在30%～50%之间。     

Micromorphological and selected physical properties of a moldboard-plowed soil with and without residue cover

Changes in micromorphology and the following physical properties, air permeability, bulk density, volumetric moisture content and air-filled porosity, of bare (NR) and residue-covered (RM) soil surfaces (75 mm) that had been tilled with a moldboard plow were examined. Sampling was conducted during the growing season (May–September) and following application of artificial rain, equivalent to a 50-year storm. The soil was a Udalf formed in loess (76% silt; 21.5% clay in surface) overlying bedrock, and had a low surface organic-carbon content (1.42–1.76%).

Results showed that residue cover provided an effective barrier against early-season surface sealing. Porosity (>40-μm equivalent diameter) following rainfall simulation was much higher in the upper 15 mm of the RM surface (22.8%) than in the NR surface (7.7%). Large planar pores (> 1000 μm) in the RM subtreatment accounted for much of the difference and this was associated with a much higher air permeability in the RM subtreatment (186.6 μ²) than in the NR subtreatment (45.1 μ²). However, with a decline in residue cover during the growing season the protective effect of residue diminished. Internal slaking and associated consolidation was prominent in both subtreatments at all sampling times and was characterized by fabrics indicating marked disaggregation and particle sorting. The most extreme example of this type of particle reorganization occurred in a RM replicate from the rainfall-simulation experiment. The replicate was underlain by a zone compacted by wheel traffic. A major drough period occurred during July, and samples taken from both subtreatments at the end of the month immediately after a 38-mm rain were sealed and internally consolidated. The RM subtreatment showed some evidence of reaggregation by the beginning of September. This may have been associated with a net increase in its subsurface residue content and an increase in soil moisture content during August. The observed differences in surface-sealing characteristics among subtreatments were manifested in significant differences in air permeability. The other physical measurements were less sensitive to these short distance changes in pore geometry.     

面向对象土地覆被图像组合分类方法

研究了支持向量机在面向对象土地覆被图像分类中的应用技术,提出采用最小二乘支持向量机（LSSVM）与模糊灰色关联度联合评估（FG）相结合的一种新的组合分类方法简记FG-LSSVM,为土地覆被分类提供一种可行的高精度分类途径。根据图像上不同对象的空间尺度和光谱值特征,基于稳健的核密度梯度分割算法提取具有任意形状和唯一标识的均质对象后,为了比较提出方法的性能,采用原始对象样本依次验证了3个面向对象分类方法,即标准支持向量机方法、以模糊贴近度作为模糊因子的模糊支持向量机方法和传统K最近邻面向对象分类方法。实现了一个高精度面向对象土地覆被图像分类信息系统。试验结果表明：提出的FG-LSSVM面向对象方法相比标准支持向量机、模糊支持向量机与K最近邻方法试验精度约提高2.4%左右。提出的方法在识别效果上,符合研究区实际分类应用的要求。     

饲料原料种类在线识别系统设计与试验

入仓原料种类识别是饲料生产过程中的关键环节之一。目前,入仓原料主要通过人工取样的方式,依靠工人感官经验识别原料种类,以确保原料正确入仓。为了实现饲料原料种类在线自动取样和识别,提高饲料加工的自动化水平,该研究设计了一种多通道饲料原料自动取样装置,应用机器视觉技术,搭建了原料种类在线识别系统。该系统主要由取样单元、样品输送单元、图像采集单元等组成;采用Arduino Uno为系统控制核心,设计了控制流程和控制线路;在Arduino IDE开发环境下编写了控制程序;运用卷积神经网络的方法构建了饲料原料种类识别模型CAM-ResNet18;基于PyQt5环境开发了饲料原料种类在线识别系统软件,包括上位机人机交互软件系统和下位机自控控制系统。上位机系统软件通过串口与下位机控制器通讯,实现对饲料原料种类在线取样识别装置的自动控制。通过模型嵌入和系统集成,对系统的基本功能、识别准确率和识别时间进行测试。饲料原料种类在线识别系统运行正常可靠,实现了饲料原料入仓过程中的自动取样、图像采集、种类识别、结果反馈、一键报警的全环节智能操作。系统性能测试中,饲料原料种类识别准确率为98%,取样识别周期为10.13 s。研究结果表明开发的饲料原料种类在线识别系统可以实现入仓饲料原料在线取样和种类识别功能,为饲料加工中饲料原料种类的自动识别提供了新的方法和技术支撑。     

Evaluation of an aluminum digestion block for routine total soil phosphorus determination by alkaline hypobromite oxidation

Abstract

Total soil P was determined in six soils differing in pH, and in organic matter, total Fe, clay and sand contents. This study was undertaken to determine whether replacement of a sand bath.digestion procedure by an Al‐block digestion procedure affected the efficacy of an alkaline NaOBr method for determining total soil P. An Al digestion block was used for soil oxidation with NaOBr‐NaOH and the results were compared with a sand bath NaOBr method and a HC1O4 method. Temperature variability was very low in the digestion block (S.D.= ±1.4°C) when compared with the sand bath (S.D.= +20.1°C). The digestion block resulted in a greater precision in total P determination when compared to the sand bath (S.D.= ±3.7 vs. ±5.6, respectively). Linear relationships were obtained with the sand bath digestion technique (R² = 0.981) and with the HC1O₄ method (R² = 0.982). Using an Al digestion block for NaOBr‐NaOH oxidation of soils for total P determination allows for a simple, precise alternative to sand bath digestion and to potentially hazardous HClO₄ procedures.     

一种测定土壤水分迁移率的方法研究

A new laboratory method was proposed to establish an easily performed standard for the determination of mobile soil water close to real conditions during the infiltration and redistribution of water in a soil. It consisted of applying a water volume with a tracer ion on top of an undisturbed ring sample on a pressure plate under a known suction or pressure head. Afterwards, soil water mobility was determined by analyzing the tracer-ion concentration in the soil sample. Soil water mobility showed to be a function of the applied water volume. No relation between soil water mobility and applied pressure head could be established with data from the present cxperiment. A simple one- or two-parameter equation can be fitted to the experimental data to parameterize soil water mobility as a function of applied solute volume. Sandy soils showed higher mobility than loamy＂ soils at low values of applied solute volumes, and both sandy and loamy soils showed an almost complete mobility at high applied solute volumes.