摘要:

Twenty surface soil samples, representing two major soil orders alfisols and vertisols were extracted with 0.01N Na2EDTA solution (pH 4.8) at a soil/solution ratio of 1:25. Phosphorus in the extract was determined following ammonium molybdate‐stannous chloride colorimetric method. The EDTA extractable P showed significant positive correlations with extractable P according to the Olsen, Morgan, Bray 1 and 2 and also with inorganic phosphorus fractions associated with Al, Ca and Fe.

ISSN:0010-3624    

DOI:10.1080/00103627709366721

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

An efficient sampling scheme for evaluating seasonal changes of inorganic nitrogen in a forest soil was designed. It was based on variances of ammonium‐ and nitrate‐nitrogen estimated from core samples from each of three horizons (A1, A2, B1) taken from 8 randomly selected sites in a three‐hectare study area. The scheme adopted was: At each sampling time a single composite sample for each horizon was made using 15 cores from randomly‐selected locations; duplicate subsamples from each composite were analyzed for ammonium‐ and nitrate‐nitrogen.

ISSN:0010-3624    

DOI:10.1080/00103627709366722

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The concept of the critical nutrient level in relation to plant growth has been described. The critical deficiency level (CDL) is the nutrient concentration in the tissue associated with a 10% growth reduction from maximum growth due to a deficiency. The critical toxicity level (CTL) is the nutrient concentration in the tissue associated with a 10% reduction in growth from the maximum due to toxicity. Critical Ma deficiency levels were established at 10 and 15 μg/g for blade 3 in cotton and sorghum, respectively, and from 10 to 15 μg/g for mature sugar beet blades. Critical Zn deficiency and toxicity levels in cotton (blade 3) were determined as 11 and 200 μg/g, respectively. Additional research in establishing the critical levels for other nutrients and crops is needed to provide nutrient ranges within which maximum plant growth and yield would result. Research is also needed in coordinating soil tests with plant tissue to determine initial soil test values that would sustain plant nutrient values within the adequate range throughout the growing season.

ISSN:0010-3624    

DOI:10.1080/00103627709366723

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Total N, P, K, Ca, and Mg concentrations were determined in corn (Zea maysL.) and in southern pine seedlings (Pinussp) grown in N, P, and K response experiments in greenhouse pots. Analyses of variance were made for dry matter yields, for nutrient concentrations, and for nutrient uptake determined for individual pots and calculated as percent nutrient of composite samples times individual pot dry matter.

ISSN:0010-3624    

DOI:10.1080/00103627709366724

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Soil Samples (72) were collected from the Delta, Hill, and Northeast Blackland areas of Mississippi. Chemical analyses for manganese, magnesium, and calcium were made using the Mississippi Soil Test Solution (MSTS) and several other extracting solutions chosen for comparison. For the determination of available soil manganese, the MSTS proved to be as effective as either the Double Acid (0.025NHCl in 0.05NH2SO4) or 0.1NH3PO4. The acid extractants removed more manganese than 1NNH4OAc (pH 7.0) and therefore included forms that are not exchangeable. The methods studied for magnesium determinations were equilibrium extraction with 1NNH4OAc, MSTS, Double Acid, 0.25NCaCl2, and leaching with 1NNH4OAc. All methods were highly correlated and therefore would be equally effective in determining available soil magnesium. Since MSTS and equilibrium extraction with 1NNH4OAc removed similar amounts of magnesium from the soil, the same calibration can be used. Calcium determinations were made using equilibrium extraction with 1NNH4OAc, MSTS, and Double Acid, and by leaching with 1NNH4OAc. All methods proved effective in measuring available soil calcium on acid soils.

ISSN:0010-3624    

DOI:10.1080/00103627709366725

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

A gas regulating device is described which reduces errors in flame photometric determinations caused by fluctuations in main gas supply.

ISSN:0010-3624    

DOI:10.1080/00103627709366726

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

A method for the analysis of soil extracts and plant tissue ash solutions is described using a direct reading plasma emission spectrometer. The instrument is programed for 16 elements and is capable of determining the elemental content in prepared solutions at a very rapid rate and at sensitivity levels equal to or better than that obtained using the atomic absorption technique.

ISSN:0010-3624    

DOI:10.1080/00103627709366727

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103627709366720

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor