Plant Analysis Council Research Articles

Fertcare: A Model for Linking Soil and Plant Testing with Quality Assurance for Interpretation

Fertilizers provide an effective way to replace valuable plant nutrients that are removed in crop and animal products. Fertilizers also have potential to harm other ecosystems or impact food safety. Soil and plant testing is the foundation of management practices appropriate for specific sites and farming systems. Food safety and environmental issues associated with nutrients are areas of policy focus and public debate. The environmental issue of greatest concern for the Australian fertilizer industry is eutrophication. Recently there has been a strong public policy focus on the problem of transport of nutrients into the Great Barrier Reef catchments. The fertilizer industry has had significant involvement in developing policy responses to this issue. The industry has made a commitment to effectively manage environment and food safety issues by developing and delivering a fertilizer product stewardship program, Fertcare. This program is grounded in accepted science with the technical content of the program overseen by a committee of leading public- and private-sector experts in the fields of soils, plant nutrition, food safety, and environmental science. It is further strengthened by training that meets national competency standards and accredited advisors, who are independently audited every two years to ensure that they meet rigorous standards set by the Australasian Soil and Plant Analysis Council (ASPAC).With 2,400 people trained and 345 accredited advisors, Fertcare is a powerful tool in implementing practices that reduce environment and food safety risks. Fertcare provides strong assurance to government, consumers, and farmers that sound practices are being followed, and the program integrates nutrient management, public policy, and food quality assurance schemes. Fertcare underpins the significant contribution of the fertilizer industry to the development and implementation of good public policy to deal with issues associated with the use of fertilizer products. Fertcare helps ensure that sound science is put into practice by land managers through provision of consistent advice. This article provides a case history and description of the Australian Fertcare program.

New, Comprehensive Soil Chemical Methods Book for Australasia

The 1992 Australian Laboratory Handbook of Soil and Water Chemical Methods (the handbook) of Rayment and Higginson defines much of the contemporary soil chemical methodology used in Australia for soil fertility and land-resource survey assessments. In addition, codes from the handbook identify methodological details in Australian soil databases, while the codes summarize most tests used for certification purposes by the Australasian Soil and Plant Analysis Council (ASPAC) in its interlaboratory soil proficiency testing programs. A worthy, comprehensive replacement was required as the handbook is out of date in places and out of print. This article provides information on the handbook's replacement with a new book by Rayment and Lyons, titled Soil Chemical Methods-Australasia. Method codes and other strengths of the handbook have been retained and many new tests have been added. There are new chapters on acid sulfate soils, total miscellaneous elements, and miscellaneous extractable elements, plus inclusions and improvements throughout. Modern analytical techniques, such as flow-injection analysis, inductively coupled plasma–mass spectroscopy (ICP-MS), and potential alternatives to chemical testing offered by near-range and midrange infrared diffuse reflectance spectroscopy, are included. Examples of new additions include the Mehlich 3 “universal” soil test (and derived environmental P tests) and methods for potentially mineralizable nitrogen, labile carbon, particulate organic carbon, and charcoal. Around 200 methods are fully described, while information of measurement performance at different concentrations is provided where credible data were available from multiple, interlaboratory proficiency programs of ASPAC. Procedures for the chemical testing of water are no longer included, except where relevant to saturation extracts of soils. While there are informative and much expanded method preambles and reference lists, the new 2011 book has its focus on methodology. A scheme to agree on recommended methods for different soils and regional locations is outlined.

Use of Reference Soils in Determinations of 0.01 M Calcium Chloride Available Metals

There are few readily available standard reference soils for which 0.01 M calcium chloride (CaCl2) soil extraction available metals data are available. This study assessed the ease with which new available metals data could be generated for reference soils. Data on 0.01 M CaCl2 available elements for four reference soils from the Wageningen Evaluating Programs for Analytical Laboratories and three reference soils from the Australasian Soil and Plant Analysis Council proficiency testing program are presented. It is difficult to generate new 0.01 M CaCl2 available metal values for standard reference soils, because trace element concentrations are low and measurements have relatively high variability. We suggest that laboratories can use reference soils as quality control samples in the analysis of 0.01 M CaCl2 available metals by reporting recoveries for major elements (e.g., potassium [K], magnesium [Mg], and sodium [Na], for which reference values are of high reliability) to provide assurance of acceptable extraction efficiency.

Soil and Plant Analysis Council: A Model for Scientific Innovation, Education, and Development

Soil and plant analysis has been a major contribution to the development of the agricultural sciences and indirectly to sustaining mankind. The advances that have occurred in the various disciplines in soil science, agronomy, and crop science would have been impossible without parallel advances in analytical technology. Despite the many divisions in the journals of the Soil Science Society of America, Crop Science Society of America, and American Society of Agronomy, none is solely devoted to the discipline of analysis of soils and plants and related areas. However, the Soil and Plant Analysis Council (SPAC) fills that critical void because it is an international society of scientists, educators, and private and public organizations with a common interest in promoting analysis of soils, plants, water, manure, and fertilizers. The primary emphasis is on nutrients in relation to crop production and increasing environmental issues. The main goal of SPAC is to provide leadership in the development and dissemination of methodology, interpretation, and application of analysis for efficient resource management and environmental protection. Its activities include publications (methods handbooks, symposia and workshop proceedings, newsletter), liaising with national agencies and commercial organizations to standardize and improve analytical procedures, maintenance of a laboratory directory, and holding international symposia. The Council has played a significant role in expanding the breadth, depth, and scope of analytical technologies in North America as well as internationally.

Laboratory Measurement Performance of Total Plant Cadmium as One Prerequisite to Manage for Soil Cadmium Minimization

Australia's National Cadmium Management Committee (NCMC) agreed to examine and publicize contemporary laboratory measurement performance for total plant cadmium (Cd) as part of its charter to implement the country's National Cadmium Minimization Strategy (NCMS). When the strategy was released in 2000, there was no published information for growers, merchants, and regulators identifying Australian laboratories competent to measure this regulated heavy metal. A special effort by NCMC, with support from the Australasian Soil and Plant Analysis Council Inc. (ASPAC), helped to propel the issue. This article outlines the steps taken to identify Cd‐competent analytical laboratories in Australia and to benchmark contemporary measurement performance for total Cd in plant materials nationally and internationally, using published interlaboratory proficiency program (ILPP) data from four ASPAC programs and from three recent rounds from the International Plant Analytical Exchange Program (WEPAL) operated by Wageningen University Environmental Sciences. The listing of 10 proficient laboratories on the NCMC website in 2003 was a first for Australia. It is evident from this detailed analytical‐performance comparison (including the relationship between median Cd concentrations and robust coefficients of variation) that there is both an Australasian and an international need to help willing laboratories improve the quality of their ongoing measurements of total plant Cd. Presently, the range in reported values for total plant Cd from 11 laboratories remaining in the ASPAC program and from up to 54 laboratories in the WEPAL program are disappointingly wide. A funded, international effort to achieve better analytical performance is required.

Initiatives of the Australasian Soil and Plant Analysis Council to Assess the Measurement Quality of Common Methods for Soil and Plant Analysis in Australasia

The Australasian Soil and Plant Analysis Council Inc (ASPAC) commenced its not‐for‐profit interlaboratory proficiency programs (ILPPs) in 1990 and issued its first soil program report in 1993. ILPPs target soil and plant chemical testing laboratories across Australasia. These ILPPs contribute to ASPAC's goals to promote excellence in all aspects of soil and plant analysis and to encourage adoption of preferred methods and protocols used in soil and plant analysis within Australasia. The ASPAC recently re‐engineered its ILPPs to increase both their frequency and the number of samples assessed in a program year, the first of which was completed in 2004–5. This article provides more details on these new ILLPs for soils and plants, including how ASPAC's method‐specific certification now operates. More than 35 laboratories undertake the most popular soil tests but less than half report results for more specialized or less common tests. Also included is an outline of comparative results from a pilot assessment of Mehlich 3 soil‐test parameters using four homogeneous samples (and results) obtained from the North American ILPP. For the most part, results were wider apart than expected, which may be confounded by storage and handling changes in the samples that also had to pass strict quarantine protocols in Australia and New Zealand. The ILPPs of ASPAC are overseen by ASPAC's Laboratory Proficiency Committee, comprised of a convenor and three others. A Technical Advisory Group operates between ASPAC and its proficiency service provider, who is now located in New Zealand.

Statistical Aspects of Soil and Plant Test Measurement and Calibration in Australasia

This article outlines the contemporary analytical performance of soil and plant analyses in Australasia. These derive from interlaboratory proficiency programs conducted by the Australasian Soil and Plant Analysis Council (ASPAC) in 2001/2002 and earlier. Contemporaneously, the best‐performed soil tests were pH (mean robust CVs around 2.2%), whereas soil methods with robust median CVs in excess of 20% included exchangeable Na, Bray‐P, water‐soluble Cl, hot CaCl2‐extractable B and KCl‐exchangeable Al. The plant tests with the lowest CVs were total C, N, and P; the worst were total Na, Al, Co, Mo, Cd, Pb, Si, and Se. For both soil and plant tests, improvements in analytical performance are less than expected, which may be due in part to some of ASPAC's interlaboratory proficiency program policies. There is brief comment on strategies that may improve analytical performance, including discussion of social perspectives that include the use of “rewards.” Analytical performance, however, is only one factor influencing outcomes from testing. Others relate to the derivation of critical values or ranges, and relationships between fertilizer rates and yields. This article draws attention to the influence statistics has on these. Relevant attributes of nonlinear models and other alternatives are discussed, with preference given to choices favoring low nutrient inputs to lessen the likelihood of off‐farm movement of nutrients to water. The consistently poor analytical performance of Bray‐P calls into question its diagnostic value, whereas there is a need in Australia to enhance the measurement quality of chemical indicators of soil salinity, particularly water‐soluble Cl by potentiometric titration.

PROFICIENCY TESTING FOR SOIL AND PLANT ANALYSIS IN AUSTRALASIA

The Australasian Soil and Plant Analysis Council Inc (ASPAC) has coordinated regular inter-laboratory proficiency programs separately for soil and plant samples since the early 1990's. Certification of proficiency to perform specific tests depended on the demerit points accrued for the test in the particular program, without heed to historical performance. In addition to describing local ad hoc initiatives to enhance soil and plant analytical quality, this paper provides feedback on longer-term laboratory performance, based on reported results for eight tests in the four most recent ASPAC plant inter-laboratory proficiency programs (20 laboratories) and the three most recent ASPAC programs for soils (12 laboratories). Laboratories were subsequently rated as Category 1 through to Category 4 (best to least-well performed). None of the 20% of laboratories rated as Category 1 for plants received a similar rating for soils, although 4 laboratories achieved at least a Category 2 rating for their combined soil and plant analytical performance over several years. Additionally, there was reasonable agreement between “as reported” median values for a selection of plant tests from five randomly selected Australasian laboratories (two from New Zealand and three from Australia) and “final” median values for the same samples and tests as documented in the 1999 Bi-monthly and the 2000 Quarterly International Plant Analytical Exchange Program reports from Wageningen. Similar international comparisons were not undertaken for soils because of differences in much of the methodology.

Analytical methods and quality assurance

The measurement of organic carbon in soils has traditionally used dichromate oxidation procedures including the Wakley and Black and the Heanes methods. The measurement of carbon in soils by high temperature combustion is now widely used providing a rapid automated procedure without the use of toxic chemicals. This procedure however measures total carbon thus requiring some means of correction for soil samples containing carbonate and charcoal forms of carbon. This paper examines the effects of known additions of charcoal to a range of soil types on the results obtained by the Walkley and Black, Heanes and combustion methods. The results show, that while the charcoal carbon does not react under Walkley and Black conditions, some proportion does so with the Heanes method. A comparison of six Australian Soil and Plant Analysis Council reference soil samples by the three methods showed good agreement between the Heanes method, the combustion method and only slightly lower recoveries by the Walkley and Black procedure. Carbonate carbon will cause an overestimation of soil organic carbon by the combustion method thus requiring a separate determination of carbonate carbon to be applied as a correction. This work shows that a suitable acid pre‐treatment of alkaline soils in the sample boats followed by a drying step eliminates the carbonate carbon prior to combustion and the need for an additional measurement. The measurement of carbon in soils by high temperature combustion in an oxygen atmosphere has been shown to be a rapid and reliable method capable of producing results in good agreement with one of the established dichromate oxidation procedures.

Soil analysis: an interpretation manual

Soil Analysis: An Interpretation Manual is a practical guide to soil tests. It considers what soil tests are, when they can be used reliably and consistently, and discusses what limits their application. It is the first nationally accepted publication that is appropriate for Australian soils and conditions.
 The first three chapters review the general principles and concepts of soil testing, factors affecting soil test interpretation and soil sampling and handling procedures. The next two chapters describe morphological indicators of soil and include colour plates of major Australian agricultural soils.
 These are followed by a series of chapters which present soil test calibration data for individual elements or a related group of tests such as the range of soil tests used to interpret soil acidity. Each of these chapters also summarises the reactions of the particular element or parameter in the soil and describes the tests commonly used in Australia.
 The final chapter presents a structured approach to nutrient management and making fertiliser recommendations using soil test data.
 The manual will be of particular interest to soil and environmental scientists, farm advisers, consultants and primary producers who will find the manual an essential reference to understanding and interpreting soil test data. Many of the soil tests evaluated in the book are used throughout the world.
 Soil Analysis: An Interpretation Manual was commissioned and developed by the Australian Soil and Plant Analysis Council (ASPAC). It comprises the work of 37 experts, which has been extensively peer reviewed.

Australian Soil and Plant Analysis Council soil and plant quality assurance programs and the impact of variability of test results on clients

Summary. In relatively few years, the Australian Soil and Plant Analysis Council Inc. (ASPAC) has conducted 2 inter-laboratory proficiency programs on plant material and 3 inter-laboratory proficiency programs on soils. The purpose of these performance-based programs is to enhance the quality of soil and plant analysis in Australasia, with guidance where necessary from the soil and plant expertise of ASPAC members. ASPAC’s inaugural ‘Accreditation Committee’ reviewed published standards and existing laboratory accreditation/proficiency programs in Australia and internationally before developing what is now in full operation. This historical perspective and the 12 principles that guide operations of ASPAC’s soil and plant proficiency programs are described, as are the numeric procedures used to determine satisfactory performance. Certificates are issued to successful laboratories on completion of each program. Moreover, these remain current until signed certificates from the next equivalent program are released. Wide variations in some data sets suggest there is considerable scope to improve laboratory accuracy, particularly for soil chemical tests. Some of these differences are sufficient to markedly affect the assessment of fertiliser requirements. The present ‘Accreditation Committee’, in addition to State Representatives, serve as ‘points-of-contact’ for laboratories that require assistance to overcome problems with analytical accuracy and precision. ASPAC encourages its member laboratories to seek and maintain NATA (National Association of Testing Authorities, Australia) accreditation, in addition to participating regularly in the performance-based proficiency programs run by ASPAC.

Preface

Summary. In relatively few years, the Australian Soil and Plant Analysis Council Inc. (ASPAC) has conducted 2 inter-laboratory proficiency programs on plant material and 3 inter-laboratory proficiency programs on soils. The purpose of these performance-based programs is to enhance the quality of soil and plant analysis in Australasia, with guidance where necessary from the soil and plant expertise of ASPAC members. ASPAC’s inaugural ‘Accreditation Committee’ reviewed published standards and existing laboratory accreditation/proficiency programs in Australia and internationally before developing what is now in full operation. This historical perspective and the 12 principles that guide operations of ASPAC’s soil and plant proficiency programs are described, as are the numeric procedures used to determine satisfactory performance. Certificates are issued to successful laboratories on completion of each program. Moreover, these remain current until signed certificates from the next equivalent program are released. Wide variations in some data sets suggest there is considerable scope to improve laboratory accuracy, particularly for soil chemical tests. Some of these differences are sufficient to markedly affect the assessment of fertiliser requirements. The present ‘Accreditation Committee’, in addition to State Representatives, serve as ‘points-of-contact’ for laboratories that require assistance to overcome problems with analytical accuracy and precision. ASPAC encourages its member laboratories to seek and maintain NATA (National Association of Testing Authorities, Australia) accreditation, in addition to participating regularly in the performance-based proficiency programs run by ASPAC.

Proficiency testing for improving analytical performance in soil testing laboratories: A summary of results from the council's soil and plant analysis proficiency testing programs

Abstract In 1994, the Soil and Plant Analysis Council initiated a Proficiency Testing program for soil testing laboratories in the United States and Canada. The program consists of a semi‐annual (January and July) exchange of five soil samples. Participating laboratories can test the samples for up to ten different analytes following analytical methods recommended by geographic region. The data is collected and subjected to statistical analysis and data summaries are provided to the participants. Data summaries are reported here from results of the January, 1995 exchange. Of the analytes tested, the least variability was found for water and buffer pH while greatest variability was found for chloride and soluble salts. Variability of test results for phosphorus was greater than that of the other macronutrients regardless of soil test procedure employed. On the average, 53 to 80% of the participating laboratories had results that were within +/‐1 standard deviation of the mean for the analytes tested while ...

An accreditation program for soil and plant analysis laboratories

Abstract A laboratory accreditation program has been recently developed by the Soil and Plant Analysis Council for implementation in 1994. A brief description and outline of the proposed program is given.

Soil analysis: a review

This paper reviews most aspects of soil analysis, with particular emphasis on soil chemical testing in Australia. Water quality, sample contamination, and the effects of soil drying, soil storage, and particle size are recognised as important components in the laboratory preparation of soil samples for analysis. The subsequent effects of choice of soil to solution ratio, leaching v. equilibration, soil shaking equipment, and the choice of extracting and digesting solutions are reviewed with examples.The review includes an overview of key chemical soil tests including pH, electrical conductivity, chloride, phosphate, sulfur, exchangeable cations, and cation exchange capacity. There is an examination of field v. laboratory tests and comment on analytical quality assurance. The recent release of the Australian Laboratory Handbook of Soil and Water Chemical Methods and the emerging activities of the Australian Soil and Plant Analysis Council should ensure the direction of soil testing in Australia remains positive.

Soil testing and plant analysis in Australia

During the past 3 4 decades, there has been a modest growth in the demand for soil amd plant testing services in Australia. Such development reflects an increasing awareness by farmers that there are tangible benefits from the regular use of soil and plant analysis. Concomitant with these changes, there has been an increasing breadth and sophistication in the range of available services, instrumental advances that permit more rapid analytical throughput, evolution of computer management systems (including computer-generated reports), and a general decrease in reporting time to primary producers. These developments have not always been matched with adequate quality control and uniformity in sampling, analysis, interpretation, and fertiliser advice procedures. There is need for further research and method development leading to the introduction of universal reagents or ion exchange resin extractions, or new test procedures into laboratory routines, to enhance laboratory capacities and turnaround times or to improve interpretation skills. Advances in decision support software are also required in order to refine fertiliser advice to primary producers. The challenge for the future is the standardisation of procedures and maintenance of adequate quality control by the various agencies offering soil and plant testing services. The Australian Soil and Plant Analysis Council (ASPAC) will play a pivotal role in this process.