摘要:

Diagnostic procedures that identify nutrient deficiencies and excesses in crops will likely gain prominence in the future. One reason is environmental concerns are driving producers to more timely and judicious use of fertilizers and waste products. Economics is an equally important factor that ultimately dictates producer practices. Advancements made in global positioning systems (GPS), geographical information systems (GIS), and variable rate application technology (VRAT) have made it possible to make nutrient management practices more site specific and reduce losses through runoff and leaching. These technologies open many opportunities for tissue testing because as whole‐field fertilizer application practices become more closely scrutinized, and nutrient deficiencies will become more obvious. Diagnosing these deficiencies will likely involve a combination of new technologies, such as on‐the‐go yield monitoring devices and aerial photography to identify problem areas in fields. Various analytical procedures will be needed to characterize these problem areas. These approaches will clear the way for more precise nutrient recommendations, but a network of laboratory specialist, consultants, farm managers, and fertilizer dealers will be needed to help producers implement improved management practices.

ISSN:0010-3624    

DOI:10.1080/00103629409369082

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Accreditation of analytical chemical laboratories is becoming a must in today's world. In the case of laboratories dealing with soil and plant analysis, it is not sufficient to tally with rules for accreditation only. Across‐border standardization and validation of analytical procedures as well as participation ininternationalinterlaboratory analytical studies, are also highly important if reproducible, comparable and mutually recognized results are to be reached. The way of working of some national and international organizations in the field of accreditation, standardization and validation is described. Furthermore a few interlaboratory analytical studies are discussed in some detail to give examples of this type of work.

ISSN:0010-3624    

DOI:10.1080/00103629409369083

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

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.

ISSN:0010-3624    

DOI:10.1080/00103629409369084

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

pH measurements in soil systems present unique challenges in terms of the interpretation of the values obtained. The principles behind the glass/calomel electrode system are discussed as a backdrop to pH measurements in both pure solutions and soils. The influence of the liquid junction potential and salt concentration on the pH values of soil water suspensions are discussed in detail from which it emerges that the current practice of measuring soil pH in stirred soil suspensions is likely to result in the greatest errors being incurred. This is due to the large liquid junction potential of uncertain magnitude developed in such systems. Measurements in salt solutions, such as M KCl and 0.1 M CaCl2, reduce the magnitude of the liquid junction potential substantially and make the pH values obtained more reproducible and consistent. The position of the calomel electrode salt bridge is crucial in measuring soil pH and should always be positioned in the clear supernatant solution.

ISSN:0010-3624    

DOI:10.1080/00103629409369085

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103629409369086

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The necessity for precision nutrient management has arisen from a decline in agricultural commodity prices, the advent of new technology, and demographic changes resulting in increased urbanization. Community perceptions and attitudes to agriculture, food quality and the environment are often negative: thus management of essential and beneficial nutrients as well as agriculturally undesirable ions is progressing at a more rapid pace than would be dictated by economic and technological factors alone. Some of the main agronomic reasons for developing precision nutrient management are: the potential for ground water pollution particularly nitrate; heavy metal pollution; salinity including rising water tables; nutrient run‐off into streams and rivers from cropping, pastoral, intensive livestock and horticultural enterprises; suitable crop, pasture or other ground cover to minimize soil erosion; and the introduction of new cultivars of plants.

ISSN:0010-3624    

DOI:10.1080/00103629409369087

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The inadequacies in plant nutrition and fertilizer application (dosage not according to the requirements; improper N‐P‐K ratio; lack of Ca, Mg and micronutrient supply; limited variety of fertilizers; problems related to storage, time of application, means of distribution; etc.) lead to serious environmental problems (e.g.soil acidification ‐> mobilization of potentially toxic elements: “chemical time‐bomb effect” P load of surface waters ‐> eutrophisation ‐> unfavourable changes in aquatic ecosystems, rapid silting‐up of canals and reservoires; nitrate pollution of drinking water resources ‐> human health problems; accumulation of toxic compounds from fertilizers; etc.) in many parts of the World, both in developed and developing countries.

ISSN:0010-3624    

DOI:10.1080/00103629409369088

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A method is described to quantitatively determine Aluminum (Al), Silicon (Si), and Iron (Fe) in biological materials by Inductively Coupled Plasma (ICP) spectrometry using Hydrofluoric Acid (HF) to modify the microwave digestion/dissolution method. This method was tested using five plant tissues: NIST 1547 (peach), UCD 155 (Avocado), UCD 176 (Citrus), UCD 124 (Barley Hulls), and UCD 190 (Rice Straw). Values ranged from 50–700 μg/g Fe, 400–2000 μg/g Al, and 700–70000 μg/g Si. The method uses 250 mg plant material, 0.5 mL cone. HNO3, 2.0 mL 30% H2O2, and 150 ul cone. HF in a two step program of 5 and 8 min. The sample was diluted to a final volume of 15 mL using a boron solution to neutralize excess HF. The solutions were analyzed by ICP spectrometry. A smaller sample size (100 mg) is needed to obtain complete recovery of Si from botanical material containing Si levels higher than 5000 μg/g.

ISSN:0010-3624    

DOI:10.1080/00103629409369089

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Automated Dumas methods could replace Kjeldahl digestions for the analysis of nitrogen (N), but few comparisons of these methods for plant tissue are available. Because N nutrition usually affects tissue levels of N, the influence of analytical method (Dumas and a modified micro‐Kjeldahl without salicylic acid pre‐treatment) on N determination in leaves and petioles of ‘Shogoin’ turnips grown under different N regimes was investigated. Dumas‐ and Kjeldahl‐N ranged from 1.31 to 6.70% and 1.22 to 5.77% in leaves and petioles, respectively, and Dumas‐N was significantly (p<0.01) higher than Kjeldahl‐N. This resulted in a tendency to overrate N status when available thresholds developed with Kjeldahl‐N values were use with Dumas‐N data. However, for turnip, Kjeldahl‐N could be estimated from Dumas‐N in the 1–6% range as: Kjeldahl‐N = ‐0.015(p=0.82)+ 0.858(p<0.001)Dumas‐N (p<0.01, R2= 0.98) , and developing new interpretative data for Dumas N was not necessary.

ISSN:0010-3624    

DOI:10.1080/00103629409369090

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Farm Analysis and Recommendation Manager (F.A.R.M.) is the computer program which controls the processing of soil samples at Plains Innovative Laboratory Services in Saskatoon, Saskatchewan, Canada. The program controls the flow of samples from reception through drying, grinding, and analytical processes to the printing and faxing of the results. The system prepares all the data sheets with the required standard and duplicates analyses for quality‐assurance purposes. The implementation of the processing system increases control of turnaround times and allows instantaneous localization of any sample in the system using an identification number found on the customer's copy of the sample information sheet. A target yield nitrogen (N) recommendation is generated by the system according to the nitrate soil test level and estimates of stored soil moisture at seeding and the growing season precipitation for each location. The program also estimates N mineralization and immobilization over the growing season as affected by the quantity of residues from the previous crop. A stand alone IBM‐compatible software is available to modify N recommendations for a given soil analysis based on the producer's own estimates of soil stored moisture, growing season precipitation, target protein content and target yield.

ISSN:0010-3624    

DOI:10.1080/00103629409369091

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor