摘要:

Comparatively large errors can be introduced during pretreatment steps. A close examination of the Berger‐Truog hot water extraction method (1) revealed that errors were introduced not only during the boiling but also during the filtering. Extraction methods to determine what is called “plant available boron” are poorly understood chemically, and have not been thoroughly examined. Poor standardization of the pretreatment methods leads to inaccurate and unreproducible data. In the case of the hot water extraction procedure, according to Berger and Truog (1), the most critical steps are the filtering step and the boiling. Five minutes boiling time is not enough to achieve equilibrium. Boric acid added to a soil sample could usually not be reextracted. The recovery was sometimes less than 79%.

ISSN:0010-3624    

DOI:10.1080/00103628609367744

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

An ammonium determination, based on formation of a substituted indophenol with sodiumsalicylate as phenolic reagent, has been reexamined. An increase of 70% in absorbancy compared with existing salicylate methods in soil science, and an increase in reproducibility compared with pre‐existing equivalent methods in other disciplines were obtained. The method can be applied satisfactorily for ammonium in 2M KCl soil extracts and soil and plant digests. The use of salicylate in place of phenol is advised for safety reasons.

ISSN:0010-3624    

DOI:10.1080/00103628609367745

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A computer program was developed to calculate bulk density(BD), coefficient of linear extenslbility(COLE), linear extensibility(LE), and linear shrinkage(LS) in the presence or absence of coarse fragments (>2mm). When coarse fragments are present in a soil clod, COLE and linear extensibility calculations become more complex, requiring additional equations and correction factors. The calculation of linear shrinkage is not sensitive to coarse fragments, thus requiring a single equation. This BASIC computer language program is accommodating to various parameter imputs and correction factors for fast calculation of BD, COLE, LE and LS in soil clods with and without coarse fragments.

ISSN:0010-3624    

DOI:10.1080/00103628609367746

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Samples of vegetation and faeces from heavily grazed pastures are likely to be contaminated with soil to some extent. The determination of total potassium on these samples will result in low recoveries if a wet oxidation procedure normally used for vegetation analysis is employed. However, data are presented which show that for the sites studied satisfactory recoveries of total potassium are obtained following a sulphuric acid‐hydrogen peroxide digestion, providing the ash content of the sample does not exceed 25%. For ash contents greater than 25%, alkaline fusion or hydrofluoric/perchloric acid decomposition procedures are required to obtain full recovery.

ISSN:0010-3624    

DOI:10.1080/00103628609367747

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The effects of F on the chemical components of soils were examined by equilibrating 0.0 to 2.5 mMNaF solutions with ten soils for 24 h. The solutions were then analyzed for total F, Al, Fe, Mn, Ca, Mg, K, Na, Cu, Zn, Ni, Cd, Cr, P, Si, N03, NH3, organic C, SO4, free F, and pH. The computer equilibrium program CHEMSPEC was used to calculate ion speciation in solution.

ISSN:0010-3624    

DOI:10.1080/00103628609367748

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Elemental concentrations of N, P, K, Ca, Mg, Fe, Al, Zn, Mn, and Cu in peach tree short life (PTSL) trees were compared to concentrations in apparently healthy trees in the same orchard. Leaf and stem concentration of K were significantly less and concentrations of Fe and Al were significantly greater in PTSL trees than healthy trees. Leaf concentrations of Ca and Mg and stem concentrations of N, P, and Cu were also significantly less in PTSL trees than healthy trees. Increased levels of Fe and Al and a K:Fe ratio of less than 150:1 in the leaves and stems was associated with PTSL.

ISSN:0010-3624    

DOI:10.1080/00103628609367749

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

As a prelude to laboratory and field research on pH reduction of organic and mineral soils of the Everglades, a convenient method was needed to quantify the pH responsiveness of various soils. Using 17 soils of widely differing physical and chemical characteristics, a method was developed which consisted of treatment with distilled water and 8 concentrations of HCl to apply 0 to 0.67 mmol(H+)/cm3soil. The resulting titration curves were fit to equations of the form:pH = B / [1 −EXP (−c−rx)]where:x = mmol (H+)/cm3and B, c and r are fitted parameters. Calculations based on the fitted equations provide a basis for quantitative comparison of the buffer intensity for widely divergent soils. The soils used to demonstrate the applicability of this approach are expected to bracket the responses of high‐pH soils in other locations, so a similar empirical approach should be generally useful to quantitavelycomparepH responsiveness of soils.

ISSN:0010-3624    

DOI:10.1080/00103628609367750

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The effects of liming (7 500 kg CaCO3/ha) and rate of urea application (0,50,100, and 200 kg N/ha) and its placement at the surface or at 5 cm depth on grain yield and nutrient uptake by corn grown on an acidic tropical soil (Fluventic Eutropept) were studied. Liming significantly increased grain yield, N uptake, and P and K uptake although Ca and Mg uptake, generally, were unaffected. Sub‐surface application of urea increased N uptake only. Yield response to applied N was observed up to 50 kg N/ha when limed but at all rates in the absence of liming. It therefore, reduced the fertilizer N requirement for optimum grain yield. Liming the acidic soil also reduced exchangeable Al but increased nitrification rate and available P in the soil profile (at least up to 0.6 m depth).

ISSN:0010-3624    

DOI:10.1080/00103628609367751

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103628609367743

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor