ISSN:0044-3263    

DOI:10.1002/jpln.19901530402

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractThree incubation experiments were carried out to assess the effect of different levels of sludge, salinity and of different wetting and drying cycles on amidase and urease activity in a calcareous silt loam soil. Both amidase and urease activities were largely increased with the increase in the amount of sludge applied. The addition of NH4+‐ N with sludge slightly reduced both activities. Addition of increasing amounts of a 1:1 NaCl: CaCl2salt mixture increasingly reduced the soil activities of amidase and urease. This effect was less severe in sludge amended soil. The data also showed that drying of either unamended or sludge amended soil cause a marked drop in amidase and urease activity. Rewetting increased both enzyme activitie

ISSN:0044-3263    

DOI:10.1002/jpln.19901530403

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractThe possible interaction of four nematicides (Terbufos, Carbofuran, Fenamiphos, and Aldicarb) withAzospirillum lipoferumand growth of twoZea maizecultivars was studied in a greenhouse experiment. Application of nematicides, Fenamiphos in particular, resulted in higher plant length, dry matter production and N yield over the nematicide‐untreated plants.Azospirillumspp. inoculation stimulated the growth of nematicide‐treated Z.maize. Among the nematicides used, Carbofuran and Aldicarb inhibited the nitrogenase activity on plant roots more seriously than Fenamiphos and Terbufos. Generally, the inhibition percentages in acetylene reducing activity in soil of inoculated treatments were lower (14.4 ‐ 61.8%) than those reported for the uninoculated ones (21.4 ‐ 73.9%). Soil, irrespective of treatment, regained a part of its normal N2‐ase activity with time. Field concentrations of all nematicides showed different inhibitory effects on N2‐ase activity ofAzospirillumspp. in culture medium, such effects increased with increased doses (10‐ and 100‐ fold) and incubation periods (10 days). The contribution ofAzospirillumspp. to the N economy of soil treated with nematicid

ISSN:0044-3263    

DOI:10.1002/jpln.19901530404

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractBuchenjungpflanzen wurden in belüfteten Nährlösungen über einen Zeitraum von 12 Wochen mit NH4‐ bzw. NO3‐Stickstoff ernährt. Die aus der N‐Form resultierenden pH‐Wert‐Änderungen wurden im Abstand von 2 Tagen korrigiert. NH4‐N wurde von den Pflanzen im Vergleich zu NO3‐N bevorzugt aufgenommen. Sproßwachstum und Seitenwurzelbildung waren bei NH4‐N, das Längenwachstum der Hauptwurzel dagegen bei NO3‐N‐Ernährung überlegen. Den günstigsten Einfluß hatte

ISSN:0044-3263    

DOI:10.1002/jpln.19901530405

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractBuchenjungpflanzen wurden in belüfteten Nährlösungen über einen Zeitraum von 14 Wochen gestaffelten Al‐Konzentrationen ausgesetzt. Stickstoff wurde den Pflanzen entweder als Ammonium Oder als Nitrat angeboten. Die aus der Form der Stickstoffernährung resultierenden pH‐Wert‐Änderungen wurden entweder alle 2 Tage korrigiert (Ausgangs pH‐Wen: 4, 0) oder innerhalb eines 2wöchigen Versuchsabschnittes nicht verändert. Das Wurzelwachstum der Buchenjungpflanzen wurde durch Al behindert. Die Reduktion der Wurzellänge und der Trockensubstanzproduktion der Wurzel waren bei NH4‐N‐ stärker als bei NO3‐N‐Ernährung ausgeprägt. NH4‐N‐Ernährung führte zu einer pH‐Wert‐Abnahme und infolgedessen zu einer erhöhten Verfügbarkeit und damit Toxizität von Al3+‐Ionen im Medium und in der Wurzel. Im Gegensatz dazu führte NO3‐N‐Ernährung zur Abschwächung der Al‐Toxizität, da NO3‐N‐Ernährung den pH‐Wert an der Wurzeloberfläche und im AFS anhob und dadurch das Aluminium in Form unlöslicher Hydroxy‐Al‐Polymere inaktivierte. Gegenüber NO3‐N‐förderte NH4‐N‐Ernährung das Sproßwachstum von Buchenjungpflanzen. Innerhalb des 14wöchigen Untersuchungszeitraumes war kein

ISSN:0044-3263    

DOI:10.1002/jpln.19901530406

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractBuchenjungpflanzen wurden in belüfteten Nährlösungen über einen Zeitraum von 14 Wochen gestaffelten Al‐Konzentrationen ausgesetzt. Stickstoff wurde den Pflanzen entweder als Ammonium oder als Nitrat angeboten. Die aus der Form der Stickstoffernährung resultierenden pH‐Wert‐Änderungen wurden entweder alle 2 Tage korrigiert (Ausgangs‐pH‐Wert: 4, 0) oder innerhalb eines 2 wöchigen Versuchsabschnittes nicht verändert. Sowohl der Sproß als auch die Wurzel enthielten bei NO3‐N‐Ernährung höhere Ionengehalte als bei NH4‐N‐Ernährung. Gestaffelte Al‐Gehalte der Nährlösungen führten bei beiden Stickstofformen zu einem Anstieg der Al‐Gehalte und einer Abnahme der Ca

ISSN:0044-3263    

DOI:10.1002/jpln.19901530407

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractThe water‐soluble carbohydrate components of four horizons of two forest soils from West Germany, a Moder and a Mor humus profiles, were investigated in this paper. A fractionation scheme, which utilized a macroreticular resin (XAD‐7) and various hydrolysis steps, divided the water‐soluble saccharides, into monosaccharides (MS), polysaccharides (PS), and humic‐bound saccharides (HS), finally detected and quantified by means of HPTLC. Monosaccharides, which constitute the richest fraction of all the water‐soluble saccharides in the upper horizon, rapidly decrease through both humus profiles but appear to accumulate in the mineral horizon (Ah). Polysaccharides show a much slighter decrease as depth increases, but increase sensibly in the deepest horizon as well as the humic‐bound saccharides. In all fractions, glucose was generally much more concentrated than the other sugars, often occuring onl

ISSN:0044-3263    

DOI:10.1002/jpln.19901530408

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractA laboratory experiment was conducted to investigate the relative mobility of dicyandiamide (DCD) and jointly applied ammoniacal salts or urea in three different soils of lower Egypt, and to determine the extent to which DCD separates from N‐fertilizer in unsaturated soil undergoing leaching.The experimental results suggest that, under conditions of water flow, DCD is readily separated from NH4+but parts from urea to a far lesser extent. The large difference in mobility between DCD and NH4+should severely limit the effectiveness of DCD as a nitrification inhibitor in the three soils considered when applied in conjunction with ammoniacal salts. In two out of three cases, the situation is similarly unfavorable in the case of joint DCD and urea application. However, the observation that DCD, in a low CEC sandy loam, moves within the soil solution at a slightly lower rate than urea suggests that joint application with urea would keep at least part of the DCD in contact with the NH4+ions and, therefore, would preserve some of the effectiveness of DCD under leaching conditions in this soi

ISSN:0044-3263    

DOI:10.1002/jpln.19901530409

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractUreaform (UF) is a condensation product between urea and formaldehyde consisting of short chains from methylene‐diurea to tetramethylenepentaurea. The rate of nitrogen release is mainly related to chain solubility. The mineralization of UF is governed by microbial activity. A wide spectrum of organisms is known to be involved. The degradation is mainly influenced by the biological fertility of the soil, temperature and to a limited degree by moisture, whereas pH and particle size have no pronounced effect. The importance of the activity index (A.I.) as a unit to evaluate the quality of an UF product and the versatility of the UF system in general are discussed. More recent trial results with UF products show the beneficial effects of the particular kind of slow release nitrogen fertilizer in meeting needs for improved fertility management and reduced pollution of drainage water

ISSN:0044-3263    

DOI:10.1002/jpln.19901530410

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractThe mean and range of indium content in unpolluted soils (Humic Andosols, Eutric Fluvisols, and Mollic Gleysols) was found to be 0.037 (0.016–0.078) μg/g dry wt. In soils polluted by common heavy metals, elevated values of indium up to 1.92 μg/g dry wt were observed together with an increase of cadmium, zinc, and lead. In contrast to indium, gallium content in polluted soils was nearly the same as that in unpolluted soils throughout the profiles. The mean and range of gallium content in all unpolluted and polluted samples was 14.2 (12.8–16.3) μg/g dry wt. The indium and gallium contents in 4 Canadian reference soils were also an

ISSN:0044-3263    

DOI:10.1002/jpln.19901530411

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY