摘要:

A method has been developed for the selective determination of vanadium(IV) and vanadium(V) after interaction of VO3‐with plant roots. The separation of the two forms is possible, after dissolution in 1N HC1, by complexing selectively vanadium(IV) with cupferron and extracting the complex with CHC13. The quantitative determination of vanadium was carried out by direct current plasma (DCP) emission spectrometry.

ISSN:0010-3624    

DOI:10.1080/00103628809367945

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The top two horizons of 14 major hill land soils of the Appalachian Region were evaluated for activities of add phospha‐tase (AP), pyrophosphatase (PP1), arylsuifatase (AS) and urease (UR) enzymes. A relationship between enzyme activities and soil properties was examined. Surface horizons contained higher enzyme activities than the subsurface horizons. Overall, enzyme activities were positively correlated with soil moisture content, percent water‐filled porosity, C, N, K, Mn and CEC. Activities of AP and PP1 were negatively correlated with soil pH. The AP and UR activities were positively related to various forms of P. Enzyme activities were positively related to total and organic S. Pot trial was performed 1n green house conditions to evaluate the relationship between enzyme activities and snapbean (Phaseolus vulgarisL.) growth and N, P, and S uptake. With a few exceptions, activities of AP, AS and UR were positively related to snapbean shoot wt. and shoot content of N, P, and S. The PP1 activities of subsurface horizons were positively related to shoot wt. and mineral content. Enzyme activities varied from one soil horizon to another. The effects of various soil properties and their interacting factors on activities of the four enzyme systems are discussed.

ISSN:0010-3624    

DOI:10.1080/00103628809367946

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Since the movement of lime down the soil profile is extremely limited and the incorporation of lime into subsoil requires large amounts of energy, the use of a soluble, surface applied ameliorant that would move into the deeper soil horizons resulting in amelioration of the subsoil is highly desirable. Phosphogypsum (PG), a by‐product of the phosphoric acid industry, has been evaluated for this purpose, and yield responses have been highly promising, although the mechanism of PG induced amelioration of subsoil acidity is not clear. Effects of PG on subsoil solution properties and aluminum (Al) speciation have been evaluated in this study. A subsoil sample from the Appling series’ (Typic Hapludults) was treated with either increasing levels of PG (2, 5, and 10 Mg ha‐1PG), reagent‐grade CaSO4.2H2O (2 Mg ha‐1), or CaCl2.2H2O (2 Mg ha‐1) and incubated (22 ± 2°C) at ‐0.01 MPa moisture potential. Soil solution was extracted after 14 and 40 d by centrifugation at 2500 g. Soil solution pH was 5.67 in untreated soil, while increasing application of PG from 2 to 10 Mg ha‐1decreased the soil solution pH from 5.08 to 4.47. The soil solution pH was higher in soils treated with similar rates of PG or CaSO4.2H2O than CaCl2.2H2O. Increasing levels of PG increased the concentrations of Ca, Mg, K, P, Na, Si, Mn, F and SO4in the soil solution. The concentration of total Al in soil solution was 0.02, 1.95 and 5.25 ppm in soils treated with 2, 5 and 10 Mg ha‐1PG, respectively. However, Al speciation predicted by the GEOCHEM computer program revealed that at the 5 Mg ha‐1PG treatment, 99% and 0.6% of total Al was complexed with F and SO4, respectively, while only 0.3% was in Al3+form. At the 10T ha‐1PG treatment, although 10% of total Al was in Al3+form, the activity of Al was only 0.11 ppm. Therefore, an increase in concentrations of F and SO4in soil solution in PG treated soils may alleviate Al toxicity by formation of less phytotoxic Al‐F and A1‐SO4complexes. The toxicity of Al may be further decreased by a reduction in activity of Al3+due to an increase in soil solution ionic strength in PG treated soils.

ISSN:0010-3624    

DOI:10.1080/00103628809367947

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A laboratory study was conducted with 2 objectives: i. to determine the effects of salinization on the cation composition of saturation paste and soil solution extracts and ii. to determine the accuracy with which the saturation extract, the traditionally used method, reflects the composition of the soil solution, the ionic medium in which plant roots reside. A factorial experiment including 5 sulfate salt species each applied at 5 rates was established in a loamy sand soil and the composition of the 2 extracts was determined after equilibration.

ISSN:0010-3624    

DOI:10.1080/00103628809367948

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

N loss by volatilization was measured for surface‐applied granular urea and ammonium nitrate, liquid urea‐ammonium nitrate and liquid acid urea in closed containers. Urea‐containing fertilizers lost between 10 and 451 of the N added within 10 days. The presence of a straw mulch accentuated the losses. N volatilization losses from acid urea solutions were significantly less than from granular urea. Addition of water following surface application of granular urea significantly reduced the loss of N as ammonia from the soil. The results of this laboratory study indicate that use of acid urea for surface application of N fertilizers may reduce N volatilization losses relative to granular urea, but losses still exceed those from ammonium nitrate.

ISSN:0010-3624    

DOI:10.1080/00103628809367949

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Eleven selected soils from Denmark and Tanzania were treated with ammonium acetate (controls), EDTA, and dithionite‐EDTA (DE) to fractionate iron and (manganese) oxides. The amounts of cobalt adsorbed were determined from a 3 μM equilibrium cobalt solution, corresponding to the cobalt level in natural soil solutions using sodium nitrate (0.2 M) to suppress non‐specific adsorption, by the extracted soils as well as by two synthetic iron oxides.

ISSN:0010-3624    

DOI:10.1080/00103628809367950

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The effects of rotations and intercropping of sorghum, maize, yam and groundnuts on organic nitrogen content were examined by analyzing soil samples from a 5 year old field trial. Significantly higher soil N levels were observed under rotations that included groundnut. Cropping in sequence was apparently more effective than intercropping for maintaining soil N status. Yams also showed beneficial effects on soil organic N. Statistical analysis of results was greatly hindered by soil variability which could not be eliminated by the randomized block design. Relationships between variability, experimental design and sampling methods are discussed.

ISSN:0010-3624    

DOI:10.1080/00103628809367951

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A method employing fusion of soil clay samples with lithium metaborate (1:5 ratio) in a furnace at 1050°C for 1 hr. subsequent dissolution of the fused sample in 4% HNO3. and elemental analysis for Si, Al, Fe, Ca, Mg, K, and Ti by atomic absorption spectrometry was compared with the X‐ray fluorescence (XRF) fused disc technique for analysis. Duplicated analyses were performed on 15 clay samples from soils of the southern U.S and three API reference samples. The mean total percent recovery by this method was excellent (100.14 ± 2.85). Elemental oxide quantities in terms of SiO2. Al2O3, Fe2O3, MgO, CaO and K2O determined by atomic absorption/flame emission (AA/FE) spectroscopy were in good agreement with values measured by x‐ray fluorescence (XRF) on the same subsamples (r = 0.89*to 0.98**). but somewhat more variable on subsamples seperated from different pretreatments (r = 0.70*to 0.97**). The method, which has also been tested on 36 additional clay samples from a variety of Kentucky soils with total percent recoveries ranging from 96.5 ‐ 103.5%. demonstrated no bias due to mineralogy with respect to mixed, montmorillonitic. and siliceous classes. This technique presents numerous advantages over other elemental analysis techniques utilizing fusion, dissolution, or XRF spectroscopy with respect to time, effort and cost. With the introduction of inductively‐coupled plasma (ICP) emission spectroscopy. efficiency can be additionally improved.

ISSN:0010-3624    

DOI:10.1080/00103628809367952

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

An automated CHN Analyzer was compared with the Walkley‐Black and Kjeldahl methods for organic carbon (C) and nitrogen (N). Four organic compounds, twenty nine plant materials and five soils were tested. The CHN Analyzer gave C and N values that were not significantly different (P<0.05) to the theoretical weight percents of the organic compounds. The Walkley Black method gave soil C values significantly lower (P<0.05) than those obtained with the CHN Analyzer. The Kjeldahl method gave soil N values significantly lower (P<0.05) than the CHN Analyzer on three of five soils tested. The discrepancies observed between methods appear to be due to different oxidation efficiencies. CHN Analyzer and Kjeldahl N analyses were not significantly different (P<0.05) for the plant materials except where samples contained greater than 0.7% NO3‐N. Potassium nitrate was also added as a spike to a tall fescue sample. Based on recovery of the spiked NO3‐N, the Kjeldahl method was a poor measure of total N for plant materials containing greater than 0.7% NO3‐N. The findings suggest the CHN Analyzer can be used for the rapid, accurate and simultaneous determination of C and N in plant and soil samples.

ISSN:0010-3624    

DOI:10.1080/00103628809367953

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103628809367944

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor