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  • 1
    ISSN: 1432-0789
    Keywords: Key words Water stress effects ; Urea N ; Diazotrophic bacteria ; Plant growth regulators ; Wetland rice ; Oryza sativa L. ; Klebsiella sp. strain ; CO2 exchange ; Na content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Some of the measures suggested for amelioration of drought effects include application of N fertilizer and plant growth regulators (PGRs). Since N2-fixing bacteria produce plant growth substances (PGRs), the effect of foliar application of an active strain of Klebsiella sp. (KUPOS) on IR-50 rice was examined using three foliar sprays applied at 10-day intervals. Irrigation once every 3 days was essential for plant growth. Application of KUPOS and 40 kg N ha–1 improved grain yield of acutely water stressed plants from 330 kgha–1 to more than 1300 kgha–1 along with an improvement in several growth variables and yield determinants. Indole acetic acid, kinetin and GA3, in a mixture of 10–4 M of each, were less effective than KUPOS in alleviating stress effects. The adverse effects of water stress on respiration and photosynthesis as indicated by CO2 exchange were also alleviated by these treatments. While uptake of K, Mg, Ca, Fe and Mo was increased, Na content decreased, accompanied by an increase in proline content. The order of effectiveness of the treatments was 40 kg N ha–1 〉KUPOS〉PGRs.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 20 (1995), S. 41-48 
    ISSN: 1432-0789
    Keywords: Added nitrogen interaction ; Ammonia fixation ; 15N ; Immobilization ; Fertilizer-induced solubilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Added N interactions were measured in four soil incubated with 15N-labelled urea or diammonium phosphate. The use of biologically active, γ-irradiated, or reinoculated γ-irradiated samples allowed us to separate added N interactions due to chemical and biological processes, and to distinguish real interactions from apparent effects. Real biologically mediated added N interactions were observed in one soil for both fertilizer sources and in three soils amended with urea. These real interactions increased with the N fertilizer rate, but did not differ significantly between N sources. Fertilizer-induced unlabelled organic N in soil extracts declined during incubation in both sterile and non-sterile samples, but the temporal decline was higher in biologically active soil. Changes in fertilizer-induced unlabelled organic N in the extracts of three soils attributed to biological processes were similar to the measured real biologically mediated added N interactions. The results are consistent with the hypothesis that real biologically mediated added N interactions arise from the mineralization of soil organic N solubilized by alkaline-hydrolysing N fertilizers.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 23 (1996), S. 93-98 
    ISSN: 1432-0789
    Keywords: Added nitrogen interaction ; Alkaline-hydrolysing fertilizer ; Aqua ammonia ; Gross N immobilization ; Gross N mineralization ; 15N ; Soluble organic N availability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Organic N solubilized by NH3(aq) was extracted from 15N-labelled or unlabelled soil, concentrated and added to non-extracted soil, which was incubated under aerobic conditions at 27±1°C. Gross N mineralization, gross N immobilization, and nitrification in soils with or without addition of unlabelled soluble organic N were estimated by models based on the dilution of the NH 4 + or NO inf3 sup- pools, which were labelled with 15N at the beginning of incubation. Mineralization of labelled organic N was measured by the appearance of label in the mineral N pool. Although gross N mineralization and gross N immobilization were increased in two soils between day 0 and day 7 following addition of unlabelled organic N solubilized by NH3(aq), there was no increase in net N mineralization. Solubilization of 15N-labelled organic N increased and the 15N enrichment of the soluble organic N decereased as the concentration of NH3(aq) added increased. A constant proportion of approximately one-quarter of the labelled organic N added at different rates to non-extracted soil was recovered in the mineral N pool after an incubation period of 14 days, and the availability ratios calculated from net N mineralization data were 1.1:1 and 2.1:1 for 111 and 186 mg added organic-N kg-1 soil, respectively, indicating that the mineralization of organic N was increased by solubilization.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0789
    Keywords: Water stress effects ; Urea N ; Diazotrophic bacteria ; Plant growth regulators ; Wetland rice ; Oryza sativa L. ; Klebsiella sp. strain ; CO2 exchange ; Na content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Some of the measures suggested for amelioration of drought effects include application of N fertilizer and plant growth regulators (PGRs). Since N2-fixing bacteria produce plant growth substances (PGRs), the effect of foliar application of an active strain of Klebsiella sp. (KUPOS) on IR-50 rice was examined using three foliar sprays applied at 10-day intervals. Irrigation once every 3 days was essential for plant growth. Application of KUPOS and 40 kg N ha-1 improved grain yield of acutely water stressed plants from 330 kg ha-1 to more than 1300 kg ha-1 along with an improvement in several growth variables and yield determinants. Indole acetic acid, kinetin and GA3, in a mixture of 10-4 M of each, were less effective than KUPOS in alleviating stress effects. The adverse effects of water stress on respiration and photosynthesis as indicated by CO2 exchange were also alleviated by these treatments. While uptake of K, Mg, Ca, Fe and Mo was increased, Na content decreased, accompanied by an increase in proline content. The order of effectiveness of the treatments was 40 kg N ha-1 〉KUPOS〉PGRs.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 23 (1996), S. 93-98 
    ISSN: 1432-0789
    Keywords: Key words Added nitrogen interaction ; Alkaline-hydrolysing fertilizer ; Aqua ammonia ; Gross N immobilization ; Gross N mineralization ; 15N ; Soluble organic N availability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Organic N solubilized by NH3(aq) was extracted from 15N-labelled or unlabelled soil, concentrated and added to non-extracted soil, which was incubated under aerobic conditions at 27±1°C. Gross N mineralization, gross N immobilization, and nitrification in soils with or without addition of unlabelled soluble organic N were estimated by models based on the dilution of the NH4 + or NO3 – pools, which were labelled with 15N at the beginning of incubation. Mineralization of labelled organic N was measured by the appearance of label in the mineral N pool. Although gross N mineralization and gross N immobilization were increased in two soils between day 0 and day 7 following addition of unlabelled organic N solubilized by NH3(aq), there was no increase in net N mineralization. Solubilization of 15N-labelled organic N increased and the 15N enrichment of the soluble organic N decereased as the concentration of NH3(aq) added increased. A constant proportion of approximately one-quarter of the labelled organic N added at different rates to non-extracted soil was recovered in the mineral N pool after an incubation period of 14 days, and the availability ratios calculated from net N mineralization data were 1.1:1 and 2.1:1 for 111 and 186 mg added organic-N kg–1 soil, respectively, indicating that the mineralization of organic N was increased by solubilization.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 38 (1994), S. 131-139 
    ISSN: 1573-0867
    Keywords: aqua ammonia ; di-ammonium phosphate ; gamma-irradiated soil ; 15N ; organic matter solubility ; urea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Interactions between15N-labelled fertilizers applied at concentrations representative of the fertilizer microsite and the solubility of the nitrogenous component of soil organic matter were investigated in laboratory experiments. Soil organic N was solubilized in aγ-irradiated soil due to addition of NH3(aq), and the fertilizer-induced loss of unlabelled total N in the extracted soil (ΔTUs) increased with increasing N fertilizer concentration and soil pH. ΔTUs was linearly correlated with ammoniacal-N concentration and the pH of the fertilized soil within the range of 7.5-10 (r = 0.94). Total organic N in the soil extract (OTe) increased rapidly up to day 14 following addition of 2000 mg urea-N kg−1 soil, but was then stable up to day 28. OTe of a range of soils increased from between 5 and 148 to between 15 and 368 mg N kg−1 soil after application of 1045 mg NH3-N kg−1 soil. While up to 25% of the organic N was solubilized by the fertilizer in nine soils, the change in total organic N in the extracts (ΔOTe) of three soils was not significant. The highest ΔOTe of 399 mg N kg−1 soil (35.4% of soil organic N) was measured after application of 2000 mg NH3-N kg−1 soil. pH and ΔOTe decreased in the order of NH3(aq) 〉 urea 〉 di-ammonium phosphate 〉 ammonium sulphate at equivalent rates of N addition. A negative ΔOTe was measured following application of ammonium sulphate. ΔOTe was correlated with the pH of the fertilized soil but not ammoniacal-N concentration for different N fertilizer sources.
    Type of Medium: Electronic Resource
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