摘要:

A close relationship was found between the pH of soil suspensions in the SMP buffer solution (pHsmp) and the potential acidity of soils (H + Al) extracted by a neutral calcium acetate solution (r = 0.98), for twenty six soil samples of the State of Sao Paulo, Brazil, This relationship was represented by the equation lnY = 7.76 ‐ 1.053X, which allowed for the calculation of H + Al directly from the values of pHsmp.

ISSN:0010-3624    

DOI:10.1080/00103628509367600

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Representative samples of a group of New Zealand podzolised soils were extracted withMKCl,MNH4OAc at pH 4.8, 0.5MCuCl2and 0.01MCaCl2, and Al, Fe and Si were determined in the extracts. Total Al in the CuCl2extracts was determined by atomic absorption spectrometry, but in the other extracts both monomeric and total Al were determined by the oxine colorimetric method. Largest amounts of Al (in excess of 40 meq/100 g) were extracted by NH4OAc at pH 4.8. These were the only extracts to show marked differences between monomeric and total Al. Extraction time influenced the amount of Al extracted by the NH4OAc and CuCl2reagents. Al extracted by KCl and CaCl2was significantly correlated, and so was Al extracted by NH4OAc and CuCl2. The results are discussed in relation to clay mineralogy and the possible contributions of soluble polymeric hydroxy‐Al complexes and organic Al complexes.

ISSN:0010-3624    

DOI:10.1080/00103628509367601

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Soil P fractions have been estimated in a 30‐year‐old replicated superphosphate experiment established inPinus radiata.The treatments were 0, 25, 50, 75 and 100 kg.P ha‐lbroadcast applied and the timber productivity was increased from 144 m3ha‐lto 396 m3ha‐1merchantable volume over 30 years. The soil P fractions were basically as in the Chang and Jackson 7 p fractionation procedure, except each fraction was further separated into organic and inorganic components. The total organic P fractions accounted for more than 55% of the total P and were correlated with changes in organic matter. The results indicated an equilibrium situation had developed between the various components and that, based on correlations with tree growth, the readily soluble organic fractions could be the most important P forms for long term forest productivity.

ISSN:0010-3624    

DOI:10.1080/00103628509367602

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A simplified apparatus was tested for the distillation of H2S using hydriodic acid reagent in combination with bismuth sulphide detection. The digestion‐distillation flask is a modified Taylor tube. The tube facilitates sodium hypobromite digestion in a block digestor for total S analysis. The simplified apparatus does not include a water condenser and therefore distillation time is reduced. Thorough examination showed that the new apparatus gave essentially the same results as the Johnson‐Nishita method for sulphate and total soil S analyses. Transfer of all reduced sulphate into the collecting solution in the proposed apparatus took about one‐half the time that it took in the Johnson‐Nishita apparatus. Advantages of the proposed apparatus compared to Johnson‐Nishita and/or Tabatabai‐Bremner apparatus include low fabrication cost, flexibility to conduct both sodium hypobromite digested (total S) and undigested (sulphate S) analyses and economy of time for distillation.

ISSN:0010-3624    

DOI:10.1080/00103628509367603

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Exchangeable acidity of soils has previously been measured by titration of soil extracts to a phenolphthalein endpoint at pH 8.3. The use of standard hydrogen and aluminium solutions indicates that this is inaccurate and a preferred technique, differential potentiometric titration is proposed.

ISSN:0010-3624    

DOI:10.1080/00103628509367604

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Following the determination of total exchangeable acidity, exchangeable aluminium can be determined from the release of hydroxyl ions (OH‐) by NaF if all the aluminium has been neutralised to Al(OH),. The released hydroxyl was measured by titration to a phenolphthalein endpoint and to an isoelectric endpoint. When compared with a colorimetric procedure for Al, both titrimetric methods gave inaccurate and unreliable results for solutions containing known amounts of Al. A colorimetric method using Alizarin Red S is recommended.

ISSN:0010-3624    

DOI:10.1080/00103628509367605

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A turbidimetric test and two wet sieving tests were used to measure aggregate stabilities of soils from five neighbouring fields with different cropping histories.

ISSN:0010-3624    

DOI:10.1080/00103628509367606

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The literature published on the use of the Soltanpour and Schwab Ammonium Bicarbonate‐DTPA (AB‐DTPA) soil test shows that it can be used to determine availability and toxicity indices for many elements. It has been shown to be an effective test for measuring the availability indices of P, K, Zn, Fe, Mn, Mo, Pb, Ni, Cd and Se. Theoretically, it can also be used to determine the availability indices for S, Cu and As. The AB‐DTPA test can predict toxicity of B as well as the standard hot water rest, although within the non‐toxic range of B, it is not as effective as the hot water test. The hot water test alone predicts B availability well, but the AB‐DTPA B test result requires inclusion of soil water pH, organic matter and clay contents in a regression equation for predicting B availability. This test is not suitable for determination of exchangeable plus soluble Ca and Mg (high levels), as these precipitate as carbonates during extraction. The AB‐DTPA test procedure with analysis by an inductively‐coupled plasma spectrometer for simultaneous determination of elements, makes soil and overburden testing very efficient.

ISSN:0010-3624    

DOI:10.1080/00103628509367607

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103628509367599

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor