Assessment of soil and plant analysis laboratories in the West Asia‐North Africa Region

Abstract

Although limited amount of water is the primary constraint to agricultural productivity in the rainfed area of West Asia and North Africa (WANA), yields are also low because of the poor mineral nutrient status of soils. Yields can, therefore, be considerably increased by judicious fertilizer use. Laboratories for soil and plant analysis are essential for identifying nutrient constraints and providing a basis for efficient fertilizer use, through correlation studies to establish suitable soil testing extractants and calibration studies with crop responses. The Soils Laboratory at the International Center for Agricultural Research in the Dry Areas (ICARDA) has initiated a quality control program among the national agricultural research systems (NARS) in the countries of the WANA region. The efforts include linkages with the Wageningen International Soil Analytical Exchange Program, in‐country training courses, and a laboratory analysis manual. Continued improvement in laboratory performance is dependent upon knowledge of the capabilities of such laboratories and identification of their constraints. This presentation reports a fact‐finding survey of laboratories from 16 countries of the WANA region—mainly public, from universities and ministries of agriculture, and some private or commercial ones—based on a questionnaire about analyses, facilities, methodologies, quality assurance, personnel training, and management. Future efforts to improve the quantity and quality output from of these laboratories will address such deficiencies.     

Proficiency Tests Conducted by Soil and Plant Analysis Laboratories in Mexico

Abstract

Measurement is the comparison of a quantity against a certain standard. Measurements conducted in chemistry are usually compared against certified reference material (CRM). When a laboratory makes proper measurements, the results obtained have a low level of uncertainty; they are reliable, traceable in accordance with the International System of Units, and comparable to those made in any laboratory in the world. The purpose of this article was to determine the performance of the analytical measurements carried out by Mexico's soil and plant analysis laboratories through a proficiency testing program. The materials used for this program came from three sample batches of corn leaves, which were certified by Centro Nacional de Metrologìa of Mexico (CENAM). The critical mean quadratic error (MQEc) was used as the evaluation criterion. Although the percentage of acceptable results reported by laboratories has risen only slightly as a consequence of the proficiency testing program, it is worth mentioning that laboratory managers in Mexico are becoming more aware of the importance of quality control and the use of CRM.     

Tolerance of genetically characterized <Emphasis Type="Italic">Folsomia candida</Emphasis> strains to phenmedipham exposure

Background, Aims, and Scope  The springtail Folsomia candida is a commonly used model species in ecotoxicological soil testing. The species reproduces parthenogenetically and, thus, laboratories use different clonal lineages. In this study, we investigated if genetic divergence between F. candida strains impacts the reaction to chemical stress and may thus affect the outcome of toxicity tests. Methods  In two exposure assays (life-cycle reproduction test and avoidance behaviour test), three laboratory strains of F. candida from Portugal (PTG), Spain (SPN) and Denmark (DNK) were exposed to different concentrations of the reference chemical phenmedipham. Genetic divergence among strains was estimated based on mitochondrial COI sequence data. Results  No significant differences between tolerance towards phenmedipham exposure were observed in a reproduction test. In contrast, one strain (SPN) showed a decreased susceptibility to phenmedipham compared to the other strains (PTG and DNK) in the avoidance assay. Discussion  A phylogenetic tree based on mitochondrial COI sequences revealed clear genetic differentiation between both ‘reaction types’. Thus, we found a potential lineage dependent stress reaction in avoidance behaviour towards the pesticide. Conclusions  Our findings have implications for the comparability of test results among laboratories. Reproduction tests seem to be more robust towards interclonal genetic differentiation than avoidance tests. Recommendations and Perspectives  We recommend the use of molecular tools for simple and cost effective genetic characterization of F. candida strains used in chemical avoidance tests. Closer investigations concerning the relation between genetic relatedness and chemical response will provide a more detailed and comprehensive picture on the role of intraspecific genetic differentiation in stress tolerance. ESS-Submission Editor: Prof. Dr. Henner Hollert (henner.hollert@bio5.rwth-aachen.de)     

Uniformity,standardization and terminology: Our problems and progress

Abstract

There is increasing interest, particularly among fertilizer company soil testing laboratories, to standardize soil testing laboratory procedures and methods of reporting and interpreting soil test results. A Task Force Committee on Soil Testing was formed in 1969 by the Fertilizer Institute to formulate standard methods of testing soils. In 1971, a new organization called “Council on Soil Testing and Plant Analysis”; will begin soliciting a membership. The Council's primary objective is “to promote uniform soil test and plant analysis methods, use, interpretation and terminology”; with both organizations working toward a common goal. Considerable progress should be made toward standardizing the soil testing and plant analysis techniques.     

Quality assurance for plant tissue analysis by ICP‐AES

Abstract

A survey of 12 service laboratories using ICP‐AES for routine plant analysis reveals a variety of sample preparation and instrument calibration procedures in use. With the continued growth of ICP applications in plant analysis laboratories, a need exists for inter‐laboratory quality control.

The assurance of data quality among laboratories cannot be expected unless a standardization of preparation methods and calibration is accomplished. In the selection of a method for multi‐element determination on the same sample solution, the completeness of elemental release and sensitivity for some elements may have to be compromised.

In addition to the above survey, 8 plant samples were sent to 5 ICP laboratories that handle large volumes of plant samples with each using different preparation and calibration methods. The results for 11 elements show that the best precision among laboratories was for P, Mg, Mn, Ca and K, and the poorest precision for Al, Zn, Fe, Na, Cu and B. The imprecision noted for some elements was presumed to be caused by the diversity of preparation and calibration methods. Quality control efforts taken by this laboratory will also be given.     

Australian Efforts to Prevent the Accidental Movement of Pests and Diseases in Soil and Plant Samples

Abstract

Eradication and surveillance zones for red imported fire ant (Solenopsis invicta) embrace parts of southeastern Queensland, Australia. To lessen the risk of fire ants becoming established at new locations, those who transport soil and plant materials from affected areas for commercial reasons must comply with official risk‐management measures. This obligation is one of many that soil and plant testing laboratories in different Australian states now have a legal requirement to manage, whether samples come from within the state, interstate, or overseas. Many examples of pests and diseases of concern are provided, along with information on current pest‐management regulations. Annual soil and plant sample transactions for years 2001–2003 suggest that the regions at most risk from accidental pest and disease movement are in this order: Western Australia>Queensland>New South Wales. Large laboratories in particular are encouraged to implement a hazard analysis and critical control point (HACCP) evaluation of their sample‐handling procedures from receipt to disposal. Staff training in pest and disease awareness and recognition during all aspects of soil and plant analysis is encouraged.     

Certification of an air‐dry soil for pH and extractable nutrients using one hundredth molar calcium chloride

Abstract

The preparation of an air‐dry river‐clay soil as reference soil material for pH and extractable nutrients with a 0.01 M calcium chloride (CaCl₂) solution and the homogeneity testing are described. Recommended values for pH and the concentrations of ammonium‐nitrogen (NH₄‐N), total soluble nitrogen (N), phosphorus (P), sodium (Na), potassium (K), and magnesium (Mg) using the unbuffered 0.01M CaCl₂ are given. With respect to nitrate‐nitrogen (NO₃‐N), the sample proved not to be sufficienctly homogeneous. The certified soil sample has also been used as a sample in the International Soil‐Analytical Exchange (ISE), a continuous proficiency testing scheme. The values found by the ISE laboratories compared well with the certified values.     

Development policies and tropical deforestation in the southern Yucatán peninsula: centralized and decentralized approaches

It is well established that for multiple biophysical contexts there are legacies of past government policies in present land conditions. Despite this recognition, however, investigation of ongoing tropical deforestation dynamics often de‐emphasizes the past. The case of the southern Yucatán peninsula demonstrates the need for historical analysis in identifying key drivers of deforestation. The most important land‐use changes in the region over the past 100 years are connected to shifts in national development policies. These shifts represent tensions between centralized and decentralized approaches to land management—as represented by the policies of Presidents Díaz (1876–1910) and Cárdenas (1934–40)—that persisted throughout the 20th century. The legacies of these reoccurring development strategies include depleted hardwood reserves, large areas of permanently cleared forest, a complicated system of land allocation, and long‐standing tensions between economic, social welfare, and environmental conservation goals. These findings suggest that while centralized and decentralized approaches to development both focus on natural resource exploitation, the rates of deforestation tend to be faster, the patterns of forest clearing more pronounced, and land‐use decision making less democratic under systems of centralized control. These conclusions hold implications for land‐use decision making today. Copyright © 2003 John Wiley & Sons, Ltd.     

A comparison of the results from three soil testing laboratories using the mehlich‐3 extractant on southeastern coastal plain soils

Abstract

Soil test values from three laboratories using the Mehlich‐3 extradant on Coastal Plain soils with a wide range in soil test levels were compared. Soil samples were collected over a four year period from four Southeastern/Mid‐Atlantic states (SC, NC, VA and DL). The results among labs were highly correlated (r > 0.9) for all elements analyzed (P, K, Ca, Mg, Mn, Zn, and Cu). Regression equations were developed to predict the soil test values among laboratories for each element. Comparisons of extractable levels for the elements shown above among the three laboratories are given.     

Reaching Out: Land Grant Library Services to Cooperative Extension Offices,Experiment Stations,and Agriculture Science Centers

ABSTRACT

This paper discusses the need for agriculture librarians to more actively promote their services and library information resources to off campus extension and experiment station personnel. Services to off campus personnel include: conducting training sessions for them, providing e-mail reference, providing interlibrary loan and/or document delivery, providing access to periodical databases using a proxy server, and making visits to their off campus offices or research centers.     

Soil Testing and Plant Analysis: Building a Future on Our Legacy

Abstract

Soil testing and plant analysis have been used as diagnostic tools for assessing fertilizer needs of crops for more than 50 years. During that time, considerable progress has been made in developing a plethora of improved extraction procedures and analytical techniques, forming a considerable legacy on which to build in the future. However, as laboratories grew and methods became entrenched, a reluctance to change methodologies has caused a certain degree of stagnation and in many cases has resulted in poor prognostic precision. Examples in the realm of soil testing are presented to show what might be gained by implementing improved technology that measures parameters that are the primary yield‐determining factors. In addition, attention is focused on precision agriculture, where an urgent need exists to develop real‐time assays of nutrient levels in the soil and plants so that the appropriate rates and types of fertilizer can be applied to increase yield uniformity within a field. With the increased disposal of organic residues on land, nutrient management plans for farms are now required. Because of the associated regulations, laboratories will have to introduce protocols for analyzing soil, tissue, and water appropriate to the purpose at hand accompanied by stringent quality assurance/quality control (QA/QC) systems to meet the legal requirements. No doubt, within a short time these constraints will be applied to normal crop land being fertilized with inorganic fertilizers as the green lobby grows and applies more pressure for a cleaner environment. The implications of these changes for the future is assessed.     

Potential Use of Near Infrared Reflectance Monitoring in Precision Agriculture

Abstract

The concept of Precision farming is not new, and interest in the potential benefits gained momentum in the late eighties. The high cost of soil sampling and chemical and physical analysis by conventional laboratories has restricted the full implementation of this technique at the field level. Near infrared reflectance (NIR) could be a cost‐effective solution. Soil properties that have been calibrated include gravimetric soil water, clay content, buffer capacity, pH, electrical conductivity, titratable acidity, organic matter, mineralizable nitrogen, potential ammonia volatilization from urea, potential nitrification rate, and urease activity. A whole paradigm shift in philosophy is needed in soil testing to move away from the traditional approach of taking a perceived‐representative sample, in which all the spatial variation is lost, to using a combination of grid soil sampling at a sample intensity of 4 to 10 cores per ha and analysed separately using rapid but less accurate methods such as NIR.     

Estimation of soil texture from the sample density

Abstract

Soil texture often plays an important role in the interpretation of soil analytical data for fertilizer advisory purposes. A reliable and inexpensive method of clay content estimation is, therefore, a requirement of most advisory laboratories. This note discusses the use of sample density (i.e. the mass of a scooped volume of soil) as an index of clay content. A strong relationship was found to exist between sample density and clay content, and such estimates of clay content were superior to those obtained by experienced pedologists using the “finger test” procedure. The use of this quick and simple procedure is considered to be ideally suited to soil testing laboratories handling large numbers of samples.     

基于图谱可视化的中国大气氮沉降研究态势分析

[目的]系统地探究近10a中国大气氮沉降研究态势,为今后的相关研究提供科学借鉴。[方法]基于科学计量学与信息可视化分析方法,借助Citespace软件,从文献中分析近10a中国大气氮沉降研究热点及趋势。[结果]近10a来,在氮沉降背景下,森林生态系统中凋落物分解与土壤微生物特征一直是研究热点;近5a草地生态系统的研究地区更加广泛,但较少涉及林下草地;碳氮循环相关研究多集中于温带及亚热带森林区,研究内容更加丰富,研究方法向大数据分析及模型建立方向发展;大气氮沉降通量观测以水域生态系统为主,近5a来较多地结合了非点源污染及示踪技术。[结论]近10a来,中国氮沉降领域各学科交叉性和系统性增强,研究内容和尺度不断扩大,研究方法和技术趋于多样化;草地生态系统及微生物群落特征、氮沉降与全球变化及人类活动耦合关系研究成为近年来关注的热点。     

Microscale determination of inorganic nitrogen in water and soil extracts

Abstract

Rapid, sensitive analysis of NH₄ ^‐ NO₃ ^‐, and NO₂ ^‐ in 1–150 μL of soil extract or water was achieved using a modified indophenol blue technique adapted to microtiter plate format. The microplate technique was similar to conventional steam distillation in accuracy and precision. By varying aliquot volume, a wide linear dynamic range (0.05 to 1000 mg of NH₄ ⁺‐ or NO₃ ^‐‐NL^‐1) was achieved without the need for sample dilution or concentration. High sample throughput (250–500 NH₄ ⁺ analyses d^‐1) was accomplished manually, but could be significantly increased by automation. Of considerable importance was the very low waste stream produced by the method. All equipment and supplies required are commercially available and need no modifications for this use. The microtiter plate format could be used for other soil colorimetric analyses with little or no down time for equipment setup, a major consideration for commercial soil‐testing laboratories. The method and equipment used are well suited to quality control and quality assurance programs, as required under FIFRA Good Laboratory Practices.     

Volumetric soil measures for routine soil testing

Abstract

The design, dimensiors and materials for constructing volumetric soil measures for routine soil testing use are presented. Scoop calibration techniques are also described. Reproducibility of results obtained under routine laboratory, conditions are shown. The measures include volumes of 1.0‐, 2.5‐, 5.0‐ and 10‐ cm³ respectively.     

Interlaboratory and Intralaboratory Testing of Soil Sulfate Analysis in Mollisols of the Pampas

Sulfur (S) deficiencies in grain and forage crops have been detected in many agricultural regions of the world, but soil tests are not commonly used as the basis for S fertilizer recommendation programs. Errors of measurements of soil sulfate were determined to assess whether the variation among and within soil-testing laboratories could be a factor that prevent the adoption of soil testing to assess soil sulfate availability. Subsamples of 10 selected soils (Mollisols) from the Pampas (Argentina) were sent in two batches to five soil-testing laboratories. Laboratories were unaware of the existence of subsamples and performed routine sulfate analysis as if these soils came from 60 different fields. Soil sulfate ranged from 3.3 to 20.6 mg kg^?1. One laboratory reported sulfate values greater than the other ones, having a mean bias of 4.1 mg kg^?1 S sulfate (SO₄). The other four laboratories reported similar sulfate values when soils had low sulfate availability (less than 10 mg S kg^?1), even when they used different extractants. Considering only these four laboratories, average interlaboratory coefficients of variations ranged from 6 to 24% for the 10 soils. Within-laboratory mean coefficients of variation (CVs) ranged from 12 to 22%. However, mean absolute errors of all laboratories were less than 1.2 mg kg^?1 S-SO₄. Two laboratories reported different sulfate values for the two batches of shipment (an average difference of 4.7 and 3.8 mg kg^?1 of S-SO₄). Laboratories using different extractants obtained similar results, suggesting that using the same extractant is not a prerequisite to standardize laboratory results in these soils. Differences between laboratories in our study were smaller than in other interlaboratory comparisons for soil sulfate. These differences could be easily detected and corrected if laboratories participate in an interlaboratory control system. The observed low mean absolute errors suggested that, in general, all laboratories achieve acceptable precision when evaluating within the same batch of determinations. Differences between batches of shipment (within laboratory error) stressed the importance of using reference material for internal quality control.     

中国西南地区农业机械化现状及发展战略

中国西南地区农业机械化水平在全国最低，原因在于其不利的地理条件、落后的经济状况及大量的农村人口。提出了在新的环境条件下改善这一状况应采取的措施：利用中国加入WTO的机遇，因地制宜，采用正确的发展战略，合理地选择农业机械、机械化技术及机械化环节，借鉴外国与国内其它地区的经验，集成有关的技术、措施和政策，在机械化技术、农业机械的管理和推广、服务体系建设以及相关的措施、政策等方面实施创新，通过农业产业化、信息技术、适用技术发展农业机械化，加强研究开发工作，加强农村基础设施建设。此外，还需要一套全国性的法规政策体系来促进农业机械化工作。     

三峡库区农户水土保持行为类型及其机理

[目的]分析三峡库区农户水土保持行为的类型、特点、机理和主要效果,为区域水土保持和生态环境建设决策提供依据。[方法]对三峡库区(重庆段)5个区县113户农户进行了问卷调查和重点访谈,运用调查数据分析库区农户水土保持行为类型及其机理。[结果]三峡库区农户水土保持行为主要分自觉自愿型和政策引导型两大类。自觉自愿型是农户创造性地适应环境、保护耕地,降低投入、增加收入,以农户耕地管理和保护性耕作行为为主,农户的水土保持需求形成农户水土保持动机,产生了开挖边沟背沟、挑沙面土、大横坡+小顺坡耕作、等高耕作、免耕、反坡挖地、作物间作套种、种植植物篱和药物除草等行为。其中,间作套种、开挖边沟背沟、大横坡+小顺坡耕作和挑沙面土4项耕作行为在库区推广较好。政策引导型行为是农户受国家水土保持政策引导而参与水土保持生态建设,是国家战略需求和农户实际需要的有机结合,可以细分为三种类型,一是劳务报酬类,农户参与坡改梯等水土保持工程建设并获得劳务报酬。二是经济补偿类,农户响应国家水土保持生态建设号召,采取退耕还林等行为并获得一定补偿。三是资金补贴类,农户在政府资金前补助或后补助情况下修建塘库、道路等水土保持设施。[结论]三峡库区农户水土保持经验丰富,各种水土保持行为均具有较好效果,值得在小流域治理等水土保持生态建设中推广。     

Comparison of analytical results from plant analysis laboratories

Abstract

Analyses of 6 reference plant tissue samples were completed by 22 commercial and university laboratories across the U.S and compared. Cooperators were requested to analyze samples of apple leaf (Malus domestica Borkh.), grape petiole (Vitis labrusea L.), pecan leaf (Carya illinoensis (Wangenh.)K. Koch), snapbean leaf (Phaseolus vulgaris L.). eweet corn leaf (Zea mays L.), and rose leaf (Rosa hybrida) for the elements comprising a routine analysis. Each laboratory was requested to use their routine analytical procedures, with no attempt to standardize these methods. Close agreement between laboratories occurred with analyses of N, P, and Mg in which 80%, 69%, and 68% of the laboratories reported values within ± 5 % of the mean, respectively. Close agreement was also found for Mn and Zn, with 81% of laboratories reporting Mn and 73% reporting Zn values within ± 10% of the mean. Variation between laboratories was greater for K and S, in which 46% and 30% of the laboratories reported values within ± 5% of the mean, respectively. Values for Fe, Cu, and B were also variable, with 46%, 48%, and 46% being within ± 10% of the mean, respectively. Similiar values were reported for Ca, Mg, Mn, and Zn by laboratories using either AA spectrophotometer (AA) or ICP emisssion spectrometer (ICP) as the primary instrument. Lower values were reported by those using ICP versus AA for determination of Cu and Fe.