摘要:

AbstractIn model experiments (60 % water holding capacity and 30°C) with a loamy clay (pH 8.3) and a calcareous sand (pH 7.9) the effect of biuret upon the breakdown of urea was studied. Ammonification and nitrification occured very quickly, in case of the calcareous sand at the beginning more NH4was evolved.Biuret in concentration from 0.4 to 8 % maximum did not influence urea hydrolysis, however it resulted in higher NO2‐figures at the beginning of the experiments demonstrating an initial marked inhibition of the process NO2→ NO3especially in the calcareous sand. The total nitrification seemed to be a little retarded but did not differ very much fin

ISSN:0044-3263    

DOI:10.1002/jpln.19801430302

出版商:WILEY‐VCH Verlag    

年代:1980

数据来源: WILEY

摘要:

AbstractA field experiment conducted for two crop seasons (1976‐77 and 1977‐78) showed that the treatment of urea with nitrification inhibitor Nitrapyrin (also refered as ‘N‐Serve’) or neem (Azadirachta indicaA. Juss) cake increased its efficiency by preventing N losses and produced significantly more cane. In one of the years sulphur coated urea (Gold N) at lower rate (75 kg N/ha) gave higher sucrose content in juice and significantly more commercial cane sugar (CCS) than uncoated urea. Considering both the cane yield and CCS production mixing or coating of urea with neem cake holds considerable promise and needs wider testing along with and in comparison to nitrification inhibitors and sulphur coated urea and other slow release fertilizers for increasing the efficiency of nitrogen applied to

ISSN:0044-3263    

DOI:10.1002/jpln.19801430303

出版商:WILEY‐VCH Verlag    

年代:1980

数据来源: WILEY

摘要:

AbstractThe objective of this study was to determine the ratio and amount of Fe II and Fe III iron in different parts of 20 and 40 day old bean plants grown in pots under normal and HCO −3‐treatment. The Fe II and Fe III iron determination was carried out by a modification of a method described byVogel(1969).The Fe II and Fe III concentrations in the plant varied according to its age, the plant part, the order of leaves and HCO −3‐treatment. At the second sampling date, the lower total iron content in the lower leaf particularly under the HCO −3‐treatment suggests that the supply of iron from the roots was restricted. The iron content of the different leaves was almost evenly divided into Fe II and Fe III at the first date. At the second date, most of the iron in the bud leaf was present as Fe II. Under HCO −3‐treatment the Fe II content of the bud leaf and the flower was similar as in the corresponding parts of the normal green plants whereas the Fe III content was considerably lowered in these plant parts as result of the HCO −3‐treatment.The results indicate a substantial retranslocation of iron from older to younger leaves and a higher Fe II/Fe III ratio in flowers and bud leaves particularly u

ISSN:0044-3263    

DOI:10.1002/jpln.19801430304

出版商:WILEY‐VCH Verlag    

年代:1980

数据来源: WILEY

摘要:

AbstractThe capacity of three active Mn(IV)‐reducing isolates to dissolve Mn in sterilized samples of two Egyptian soils and a pure sand enriched with MnO2were studied. These isolates were identified asPenicillium variable(P. v.),Aspergillus niger(A. n.) andStreptomyces exfoliatus(S. e.).The data indicated that inoculation with the fungi and actinomycete mentioned increased the soil contents of water soluble + exchangeable manganese (Mnws+ex) but decreased the easily reducible form (Mner). The increase in Mn‐mobility depended on soil type, organism used and time of incubation. The maximum level of Mnws+exappeared after 14 days in the 3 soil samples. The release of Mn (II) ranged from 19.6 to 49.4 ppm in the sand samples, from 34.8 to 53.3 ppm in samples of a clay loam soil and from 9.9 to 19.8 ppm in samples of a calcareous sandy loam soil. The increase in Mnws+exwas at the expense of Mnerbut not in stochiometric amounts. The organisms tested can be ranked according to their capacity to reduce MnO2in the following order (for all soils)Streptomyces exfoliatus>Aspergillus niger>Penicillium variable.Statistical analysis of the data revealed significant differences due to inoculation, soil type, incubation time and their interacti

ISSN:0044-3263    

DOI:10.1002/jpln.19801430305

出版商:WILEY‐VCH Verlag    

年代:1980

数据来源: WILEY

摘要:

AbstractInvestigations on porosity and pedological features were carried out on thin sections of samples of a clay soil treated with a ferric conditioner. The effect of wetting‐drying cycles was considered and also surface shrinkage was determined.Micromorphometric determinations of porosity, pore size distribution and number of pores per mm2were carried out by a Leitz‐Classimat apparatus. Pore shape and pedological features of ferric compounds were analysed by the point‐count method.Surface shrinkage data show great differences between treated and control samples at the first wetting‐drying cycle but similar values at the end of the experiment.The statistical processing of micromorphometric data shows significant differences between the control and treated soil material. Wetting‐drying cycles influence the number of pores and porosity mainly in the treated soil samples. The pore size distribution is more homogeneously represented in all size classes within treated samples. Also the statistical processing of data of pore shapes and pedological features shows significant differences between control and treated soil samples. Only planar pores are not influenced by the treatment. The wetting‐drying cycles affect neither the pore shape, except for planar pores, nor the different pedologic

ISSN:0044-3263    

DOI:10.1002/jpln.19801430306

出版商:WILEY‐VCH Verlag    

年代:1980

数据来源: WILEY

摘要:

AbstractTreatment with hydrogen peroxide to destroy the organic matter shifts the surface charge towards positive values. This is in agreement with the suggestion that per oxidation produces artefacts in the soil residues, since metals released from organic matter precipitate as hydroxide coating and produce positively charged surfaces. In the presence of 0.1 M sodium pyrophosphate, treatment with hydrogen peroxide always shifts the surface charge towards negative values, notwithstanding the removal of the electronegative organic components. It is suggested that the bulk of electropositive iron and aluminium oxides in soil are associated with the organic matter and removed by the treatment, so that permanent negative charges of clay minerals dominate in soil residue.

ISSN:0044-3263    

DOI:10.1002/jpln.19801430307

出版商:WILEY‐VCH Verlag    

年代:1980

数据来源: WILEY

摘要:

AbstractDie Löslichkeit des anorganischen Bodenphosphors verschiedenartiger Böden wurde durch 15 bis 40 mal aufeinanderfolgende Extraktion mit Wasser im Verhältnis 1:50 bestimmt. Die Löslichkeits‐kurven zeigen einen exponentiellen stufenfreien Verlauf (Abb. 1), unabhängig von der P‐Bindungsform und anderen Bodeneigenschaften. Zwischen den P‐Werten der 1. Extraktion und der Summe der P‐Gehalte aus allen Extraktionen mit einer Löslichkeit von über 100 μg P/1 besteht eine enge positive Korrelation (Abb. 2). Das diffusionsfähige Bodenphosphat und damit auch die gesamten Neubildungen der Düngerphosphate sind pflanzenverfügbar. Dies ist aus der Wasserlöslichkeit des Bodenphosphors (20–140 μg P/1) nach wiederholter Wasser‐und Lactat(CAL)‐Extraktion zu folgern. Die festgestellte langsame Einstellung des P‐Gleichgewichts bei der Wasserextraktion wird auf den Einfluß einer behinderten Diffusion im Innern der Sorbentien zurückgeführt. Die Beziehungen zwischen der P‐Düngung und der Löslichkeit des Bodenphosphors (Abb. 4), sowie der ökonomisch günstigste P‐Gehalt der Böden im Hinblick auf ein optimales Pflanzenwac

ISSN:0044-3263    

DOI:10.1002/jpln.19801430308

出版商:WILEY‐VCH Verlag    

年代:1980

数据来源: WILEY

摘要:

AbstractA greenhouse study was conducted to evaluate the performance of maize (Zea maysL.) on Iwo Soil in relation to different levels of soil moisture, soil compaction and K fertilization.Reductions in dry matter yields of maize were closely associated with soil moisture stress and compaction. There was significant interaction between soil moisture and bulk density, with highest yields occurring at 17% and 21% soil moisture levels for 1.6 and 1.2 g/cm3bulk densities, respectively. Moisture stress and compaction resulted in greater reductions in the yield of roots than that of shoot. Yield and K uptake were more adversely affected by compaction compared to soil moisture stress. Addition of K increased yield and plant K content but the 60 ppm and 120 ppm rates were not significantly different in terms of improving crop performance. Implications of the results relative to long‐term management of Iwo Soil are discusse

ISSN:0044-3263    

DOI:10.1002/jpln.19801430309

出版商:WILEY‐VCH Verlag    

年代:1980

数据来源: WILEY

摘要:

AbstractDer Begriff des Phaeozems wurde im Zusammenhang mit der Weltbodenkarte der FAO‐Unesco eingeführt. Kennzeichnend für diesen Boden ist der diagnostische Mullhorizont, der nach Gefüge, Farbe, Gehalt an Kalziumionen und organischem Kohlenstoff, sowie nach Mächtigkeit usw. gewisse Anforderungen zu erfüllen hat.In den regenarmen Tälern der Schweizeralpen, zwischen etwa 600m und 1700m ü.M. kommen Phaeozeme vor. In jeder Talschaft richtet sich die Höhenstufe des Vorkommens innerhalb dieser Grenze nach den lokalen klimatischen, geologischen und geomorphologischen Verhältnissen. Voraussetzung für die Entstehung von Phaeozemen in der Schweiz ist ein kontinental getöntes Klima mit warmen, ziemlich trockenen Sommern und kalten Wintern, sowie ein gemischtes Muttergestein, glazialer, fluvialer oder kolluvialer Herkunft. Die in den Alpentälern seit der Eiszeit wirkenden Hangenergien verhinderten oft eine ungestörte Bodenbildung, weshalb gut entwickelte Phaeozem‐profile n

ISSN:0044-3263    

DOI:10.1002/jpln.19801430310

出版商:WILEY‐VCH Verlag    

年代:1980

数据来源: WILEY

摘要:

AbstractShaking of an aqueous fulvic acid (FA) solution with montmorillonite at pH 2.5 at room temperature, removed about 43 % of the FA fraction containing proteinaceous components. About 65 % of this fraction was adsorbed reversibly in interlayers, 20 % on external surfaces and 15 % was adsorbed irreversibly. The relative molar distribution of the amino acids (after hot acid hydrolysis) in the original FA, the FA fraction adsorbed in clay interlayers and in the FA fraction not adsorbed by montmorillonite was relatively uniform, indicating that clay interlayers were relatively inefficient for separating proteinaceous constituents from main structural FA components. External clay surfaces, however, appeared to adsorb peptides and/or proteins that differed qualitatively from those adsorbed on internal clay surfaces.Five successive treatments with fresh clay showed that only 61 % of the FA fraction containing proteinaceous components could be adsorbed.The original FA and all fractions separated from it by montmorillonite were able to support microbial growth without the addition of an external N source. The rate of biodegradation decreased when the FA was complexed with montmorillonite.

ISSN:0044-3263    

DOI:10.1002/jpln.19801430311

出版商:WILEY‐VCH Verlag    

年代:1980

数据来源: WILEY