摘要:

The relative effectiveness of Mehlich I (.025N H2SO4+ .05N HCl) and Mehlich III (0.2N CH3COOH + 0.25N NH4NO3+.015N NH4F + .013N HNO3+ .001M EDTA) extractants as predictors of Mn, Cu and Zn uptake was assessed in a greenhouse experiment with four Delaware soils. The soils were adjusted to eight pH levels by addition of Ca(OH)2or elemental S, and received comparable amounts of Mn, Cu and Zn as either (1) MnSO4+ CuSO4+ ZnSO4or (2) Poultry Manure. Mehlich 1 and III extractable Mn and Zn, but not Cu, were well correlated in most instances. Excellent correlations were obtained between Mn uptake and Mehlich I and Mehlich III extractable Mn, for all soils and sources. In general, however, neither Zn nor Cu was found to correlate well with plant uptake. Based on this study, conversion to Mehlich III, as a routine soil test extractant for micronutrients, would not result in a significant improvement over the currently used Mehlich I extractant.

ISSN:0010-3624    

DOI:10.1080/00103628509367664

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Four liming and Mg materials were compared in a greenhouse experiment with soybeans for their ability to raise soil pH, supply Mg, and their effect on the availability of Mn, Cu, Fe, and Zn. Three materials were added at rates of 0, 1, and 2 times the lime requirement, calcitic lime, dolomitic lime, and Hydra‐Mag (an industrial by‐product containing 20% Mg). Sul‐Po‐Mag was the fourth material added as a plus Mg check at a rate based on an equivalent amount of Mg to that supplied by Hydra‐Mag. Plant growth, plant tissue element content and extractable soil elements were determined after growing the soybeans for 5 weeks. Plants in treatments where no lime/Mg materials were added wereverysmall due possibly to Mg deficiency and Al toxicity. The 1 and 2 times rates of the materials gave about equal growth except that the high Sul‐Po‐Mag rate caused salt injury. Hydra‐Mag increased soil pH more than calcitic lime which increased soil pH more than dolomitic lime. Soil and plant Mg levels were increased more by Hydra‐Mag than dolomitic lime when applied at equivalent rates based on the lime requirement. Dolomitic lime gave very good plant growth indicating that it made adequate amounts of Mg available. Hydra‐Mag reduced plant and extractable soil Zn, Cu, and Fe but no more so than calcitic or dolomitic lime. Hydra‐Mag reduced plant Mn more than for the other limes.

ISSN:0010-3624    

DOI:10.1080/00103628509367665

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Average urea release (UR) from two Osmocote fertilizers (40–0–0 and 41–0–0) in water at 38°C and in a simulated wetland system using Crowley soil under greenhouse conditions has been studied. UR from the Osmocote granules in water seemed to be a diffusion process controlled by urea concentration gradients. It was faster when the swelling of granules was restricted than when swelling of granules was not restricted. The UR‐time curves for both Osmocote fertilizers placed at different depths (0–1, 5–10, and 10–15 cm) in simulated wetland soil were different from those placed in water. UR in the soil was rather slow; therefore, these fertilizers may not be suitable for short‐ to medium‐duration wetland rice varieties.

ISSN:0010-3624    

DOI:10.1080/00103628509367666

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Six legume species and several varieties within the species were grown in a greenhouse pot experiment using the Bt horizon of a Lily (Typic Hapludult) soil. Lime treatments were 0 and 2.2 g Ca(OH)2/kg soil. Liming increased the soil pH from 4.6 to 6.2. The species and varieties responded differentially to lime. Both shoot and root growth of legumes showed a significant species and lime interaction effect. Based on tolerance index groups for shoot growth, alfalfa varieties were classified as very sensitive, red clovers and white clovers as sensitive and Essex soybean and Carroll birdsfoot trefoil as tolerant to the acid soil. The remaining legumes were grouped as moderately tolerant to the acid soil. Liming increased shoot concentrations of Ca in all the legumes and reduced concentration of Mg, K, and Zn. Species and varieties within species differed significantly in concentrations of all mineral elements studied except Mg. Further significant differences in elemental composition were observed due to both lime and lime species interactions. In the limed soil, the Ca concentration of the shoots increased as the tolerance index decreased.

ISSN:0010-3624    

DOI:10.1080/00103628509367667

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

In this study, the rate of pyrophosphate hydrolysis was measured in four organic soil materials similar in pyrophosphate retention values and in all other respects except pyrophosphatase activity. These soil materials had a bulk density of 0.20 kg/L and a pH (0.01 M CaCl2) of 5.1, and contained 16% ash and 103 mg P/kg as Mehlich No. 1 extractable P. The difference in pyrophosphatase activity between the soil materials was attributed to response to Cu of previous crops at low values of 1 N HCl‐extractable Cu (10 vs 76 mg Cu/kg) and to pyrophosphatase inhibition by Cu at high Cu values (201 and 479 mg Cu/kg). Pyrophosphatase activity increased from 35.6 to 38.3 mmol/kg/(2h) with Cu contents increasing from 10 to 76 mg/kg, and decreased to 31.9 and 28.3 mmol/kg/ (2h) with Cu contents increasing respectively to 201 and to 479 mg/kg. However, no significant difference in course of pyrophos‐phate hydrolysis was observed among the soil materials under both laboratory and field conditions. The half‐life of pyrophosphate was nearly 1 day under laboratory conditions. The decrease in substrate concentration over time and the corresponding increase in products competing with substrate on active sites of enzymes tended presumably to mask the difference shown in pyrophosphatase activity among organic soil materials. Thus, a difference in pyrophosphatase activities larger than the one considered in this study would be required to influence the rate of pyrophosphate hydrolysis in organic soils of similar pyrophosphate retention characteristics. Such a difference in activity levels was not obtained despite a large difference in Cu contents among the soil materials. It was thus apparent that Cu contents, exceeding that generally found in Quebec organic soils, would not reduce the rate of orthophosphate production from polyphosphate fertilizers containing large amounts of pyrophosphate. Pyrophosphate hydrolysis would be rapid and not affected by a small reduction in pyrophosphatase activity.

ISSN:0010-3624    

DOI:10.1080/00103628509367668

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The determination of fluoride in plant materials was studied using a specific ion electrode following extraction using either deionized water or 0.1 M perchloric acid.

ISSN:0010-3624    

DOI:10.1080/00103628509367669

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Reclaimer‐ameliorator polymeric gel, RAPG, is tailored to suit all soil textures and climatic conditions. It imparts almost all the properties of arable lands to sandy soils and hydroponic substrates.

ISSN:0010-3624    

DOI:10.1080/00103628509367670

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103628509367663

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor