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  • 1
    Electronic Resource
    Electronic Resource
    Balance and immobilization of (15NH4)2SO4 in a soil after the addition of Didin as a nitrification inhibitor (1992)
    Springer
    Biology and fertility of soils 14 (1992), S. 23-29 
    Details
    ISSN: 1432-0789
    Keywords: Nitrification inhibitor ; Dicyandiamide ; Balance ; Immobilization ; Gross transfer processes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary We studied the effect of a dicyandiamide-based nitrification inhibitor (Didin) on the kinetics of N transfer in soil. Incubation at various temperatures was carried out in the laboratory after adding ammonium sulfate labelled with 15N. Adding Didin increased the incorporation of mineral N in a form that could not be extracted by KCl. The temperature modified the incorporation kinetics, but after 1 year, no difference remained between the two treatments in which the inhibitor had been added, and in which the total N immobilized was 26% of the 15N added compared with 13% in the control treatment. Losses of 15N, measured by difference, were greater in the control treatment (approximately 14%) than in the treatments containing Didin (10%). The addition of a nitrification inhibitor did not lead to the development of denitrifying microflora, the losses being mainly attributable to volatilization of NH3 encouraged by the high pH of the soil. The immobilized N was mainly found in the NH4 + form, adsorbed at the beginning of the incubation and subsequently in the amino acids. It seemed that the Didin effect on microflora was indirect, arising from longer maintenance of the tracer in NH4 + form. This hypothesis was borne out by computing the gross phenomena. The variation in results reported in the literature can therefore be attributed to modifications in immobilization kinetics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336298
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  • 2
    Electronic Resource
    Electronic Resource
    Can acidification associated with nitrification increase available soil phosphate or reduce the rate of phosphate fixation? (1990)
    Springer
    Biology and fertility of soils 10 (1990), S. 145-151 
    Details
    ISSN: 1432-0789
    Keywords: Nitrification ; Soil acidification ; Carbonate dissolution ; Available P ; Phosphate precipitation ; Intensive agriculture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary It is often proposed that soil acidification by microorganisms dissolves unavailable soil phosphates, especially crystalline Ca phosphates. Unavailable phosphates, it is suggested, could thus become available to crops. Microorganisms that oxidize one ammonium ion to one nitrate ion excrete two protons into the soil solution. In the present study, this universal biological process of soil acidification was used to measure, in neutral and calcareous soils, the effect of acidification on available soil phosphate and on the rate of phosphate fixation when water-soluble phosphate fertilizers are added to soils. During nitrification the Ca2+ and Mg2+ ion concentrations in soil solutions increase but the phosphate ion concentration remains constant. The excreted protons preferentially dissolve soil Ca and Mg carbonates. Soil Ca phosphates are not dissolved; they remain unavailable. When P fertilizers were applied, the rate of fixation of phosphate ions was not slowed down by acidification associated with nitrification. This biological acidification may have a long term effect, over many years, on the slow accumulation of available phosphate in soils under native grasslands, but it cannot have a significant effect on the availability of soil P under intensive agricultural practices.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336251
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of vesicular-arbuscular mycorrhizae on phosphate fertilizer efficiency in two tropical acid soils planted with micropropagated oil palm (Elaeis guineensis jacq.) (1990)
    Springer
    Biology and fertility of soils 9 (1990), S. 43-48 
    Details
    ISSN: 1432-0789
    Keywords: Vesicular-arbuscular mycorrhizae ; Fertilizers ; Phosphorus ; Acid soils ; Oil palm ; Elaeis guineensis ; Glomus spp.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The influence of vesicular-arbuscular mycorrhizae on the efficiency of triple superphosphate and rock phosphate fertilizers was compared in two tropical, acid, P-fixing soils (Ivory Coast) in which the available P was labelled with 32PO inf4 sup3- . Both soils were planted with micropropagated oil palms. The growth reponses to the fertilizer applications were low unless accompanied by VAM inoculation, but both fertilizers were equally available to plants. Isotopic-dilution kinetics analyses indicated that the rock phosphate was solubilized in both soils and there was an enrichment of the labile pool of plant-available P, similar to that with superphosphate. The specific activity and the fraction of P derived from either fertilizer was similar in both mycorrhizal and non-mycorrhizal plants, showing that both absorbed P from the same labile pool of P in the fertilized soils. However, VAM inoculation increased the fertilizer utilization coefficient of plants 2.7- to 5.6-fold, depending on the soil and fertilizer. We conclude that VAM inoculation increases fertilizer efficiency, as much of rock phosphate as of superphosphate, for plants growing in acid, P-fixing soils, and the processes involved are not different for the two fertilizers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335860
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  • 4
    Electronic Resource
    Electronic Resource
    Soil phosphorus dynamics in cropping systems managed according to conventional and biological agricultural methods (1993)
    Springer
    Biology and fertility of soils 16 (1993), S. 111-117 
    Details
    ISSN: 1432-0789
    Keywords: Available P ; Isotopic exchange kinetics ; Organic soil P ; Acid phosphatase activity ; Soil microbial biomass ; Farming systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of conventional and biological farming systems on soil P dynamics were studied by measuring some microbiological parameters after 13 years of different cropping systems. The treatments included control, biodynamic, bio-organic, and conventional plots and a mineral fertilizer treatment. The farming systems differed mainly in the form and quantity of nutrients applied and in the plant protection strategies. The results of a sequential fractionation procedure showed that irrespective of the form of P applied, neither 0.5 M NaHCO inf3 sup- nor 0.1 M NaOH-extractable organic P, but only the inorganic fractions, were affected. The residual organic P, not extracted by NaHCO3 or NaOH was increased in the biodynamic and bio-organic plots. The soil microbial biomass (ATP content) and the activity of acid phosphatase were also higher in both biologically managed systems. These results were attributed to the higher quantity of organic C and organic P applied in these systems, but also to the absence of or severe reduction in chemical plant protection. The relationship between acid soil phosphatase and residual organic P was interpreted as an indication that this fraction might be involved in short-term transformations. The measurement of the intensity, quantity, and capacity factors of available soil P using the 32P isotopic exchange kinetic method showed that P could not be the factor limiting crop yield in the biological farming systems. The kinetic parameters describing the ability of P ions to leave the soil solid phase, deduced from isotopic exchange, were significantly higher for the biodynamic treatment than for all other treatments. This result, showing a modification of chemical bonds between P ions and the soil matrix, was explained by the higher Ca and organic matter contents in this system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00369411
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  • 5
    Electronic Resource
    Electronic Resource
    Phosphatase activity in Nasutitermes ephratae termite nests (1989)
    Springer
    Biology and fertility of soils 7 (1989), S. 134-137 
    Details
    ISSN: 1432-0789
    Keywords: Isoptera ; Soil-feeding termite ; Phosphatase activity ; Organic matter ; Nasutitermes ephratae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The relationship between phosphatase activity and soil was studied in 14 mounds and adjacent control soils of plant debris-feeding termites from a Venezuelan savanna. The soils were assayed for acid phosphatase activity with p-nitrophenyl phosphate as substrate and for the effect of inorganic P (300 μg P g−1). The proportion of organic matter in the mounds was four times that found in topsoils, indicating strong selection by the termites for organic-rich soil fractions. A comparison of phosphatase activities found no difference between mounds and adjacent soils. It seems possible that the expected increase of enzyme activity in mounds, due to a higher C content, was counteracted by enzyme inhibition due to higher levels of available inorganic P in the mounds. Addition of inorganic P to soil and mound material reduced enzyme activities by 10%–45%, but after a 2-day incubation period differences between the treated soil and the control tended to disappear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292571
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  • 6
    Electronic Resource
    Electronic Resource
    Phosphorus bioavailability of fertilizers: A predictive laboratory method for its evaluation (1991)
    Springer
    Nutrient cycling in agroecosystems 28 (1991), S. 1-9 
    Details
    ISSN: 1573-0867
    Keywords: 32P ; plant P uptake ; soil P taken up by plants ; soil-plant relationships ; soil test
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A laboratory method and a laboratory index is proposed to estimate the phosphorus taken up by plants that is derived from fertilizers (Pdff). Pdff values were measured using greenhouse experiments and32P labelling technics. The laboratory index estimates the proportion of PO4-ions derived from the fertilizer in the soil solution and is measured by means of an isotopic exchange of32PO4-ion procedure. This indicator was named JCF. Two typical soil-fertilizer conditions were studied. One concerned measurement of Pdff and JCF values for freshly-applied phosphorus as diammonium phosphate (DAP) at levels of 15, 30, 45, 60 and 90 mg P kg−1 soil. The other concerned measures of Pdff and JCF values for two types of P residues previously applied in soils as concentrated superphosphate (CSP) or Gafsa rock phosphate (GRP) applied at 0 and 43.7 kg.ha−1 each year over a 15 yr period. For freshly-applied DAP a linear relationship between Pdff and JCF values was obtained over the range of 0 to 90 mg P (kg soil)−1 levels of application: JCF = 1.16 Pdff + 1.78, (r 2 = 0.98). For the P residues, JCF and Pdff values were not significantly different for a given residual treatment. However JCF and Pdff pair data for CSP treatments (56.0, 65.9) were about tenfold superior to those for GRP treatments (5.3, 4.6)). Consequently the nearly 1:1 ratio between JCF and Pdff values that was obtained for the two different soil-fertilizer conditions suggests that the proposed laboratory method can be used to predict availability of P fertilizers to plants. Thus it deserves to be considered in helping to estimate P fertilizer applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01048850
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  • 7
    Electronic Resource
    Electronic Resource
    Phosphate fixing capacity of soils: A survey, using the isotopic exchange technique, or soils from north-eastern France (1989)
    Springer
    Nutrient cycling in agroecosystems 19 (1989), S. 103-111 
    Details
    ISSN: 1573-0867
    Keywords: Phosphate ions ; soil fixing capacity ; 32P ; isotopic exchange kinetics ; northeastern France
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A large variety of soil samples was collected from farms located in two north-eastern regions of France. Their phosphate fertility was assessed by the isotopic exchange kinetics method which allows for the measurement of a r1/R ratio, where r1 is the quantity of radioactivity still present in solution one minute after the injection of a quantity of radioactivity R into a soil-solution system at steady-state. The r1/R parameter gives an estimate of the soil fixing capacity for phosphate ions (PFC). Results of the analysis of 233 soil samples revealed that the great majority of soils from these areas exhibit a high PFC. Neither the soil type nor mode of utilization appeared sufficient for prediction of the PFC. Attempts to express the PFC as a function of other soil parameters (pH, clay, organic matter, calcium carbonate and exchangeable cations), resulted in a significant regression equation involving soil clay content and soluble phosphate. Due to high PFC of soils in the Lorraine area, phosphate fertilizer could be applied at a time as close as possible to the plant requirements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01054682
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  • 8
    Electronic Resource
    Electronic Resource
    Dynamics of phosphate in soils. An isotopic outlook (1995)
    Springer
    Nutrient cycling in agroecosystems 45 (1995), S. 91-100 
    Details
    ISSN: 1573-0867
    Keywords: bioavailable P ; compartments ; isotopic exchange ; manure ; P fertilizers ; P fixation ; P release ; residual wastes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The quantities of phosphorus leached or carried away by erosion are always low in comparison with the quantity of P taken by plants. Therefore, without P application, dynamics of P in soil-plant systems depends mainly on plant P uptake from available soil P. This paper concerns mainly the description and the analysis of available soil phosphate. Available soil P is generally determined using extraction methods. It was shown, using isotopic exchange, method developed in soil-solution mixtures in steady-state, that available soil P could be described as a system with many pools. For agronomic purposes, available soil P was described with five pools of phosphate ions which have increasing rates of transfer from soil particles to soil solution. The most important is a pool which contains only directly available phosphate ions. These phosphate ions leave the solid phase of the soil to enter in the soil solution in a time shorter than 15 seconds: this time is the minimum time required to realize its determination. The intensity, quantity and capacity factors recommended to describe the available soil P are derived from experimental data characterizing this pool. The four other pools all are directly branched on this central pool. They are characterized by the quantities of P they contain and by the time required for the phosphate ions they contain to enter into the soil-solution. Effects of continuous P uptakes and of various P applications on these compartments were described. It was shown that: (i) continuous cropping without P return decreases ineluctably the intensity and quantity factors, and consequently soil P fertility (ii) applications of P quantities higher than P outputs with crops do not always increase the intensity and quantity factors, and consequently available soil P and its availability. The absolute values of the increase depends on: the type of P fertilizer or crop residues applied on the soil, on the level of soil P fertility before P application and on the fixing capacity of the soil for phosphate ions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00790658
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  • 9
    Electronic Resource
    Electronic Resource
    The role of isotopic techniques on the evaluation of the agronomic effectiveness of P fertilizers (1995)
    Springer
    Nutrient cycling in agroecosystems 45 (1995), S. 101-109 
    Details
    ISSN: 1573-0867
    Keywords: A value ; E value ; isotopic dilution ; isotopic exchange ; L value ; 32P ; P fertilizers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Many isotopic techniques can be applied to determine the relative immediate and residual effectiveness of P fertilizers. Using isotopes as tracers, the percentage of utilization by plants of the P derived from a fertilizer can be determined. However this is only possible during the three or four months after the application. Therefore, the P fertilizers may be classified only according to their relative immediate effectiveness. To also evaluate residual effect, which can be observed when more P is applied than is removed with harvest, isotopes of phosphorus can be used. This residual effect is determined by comparing pool sizes of bioavailable soil P in soils with and without P fertilizer aged in soil. The bioavailable soil P pool may be analyzed according to three isotopic experimental procedures which give access to either the A value, or the E value or the L value. The aims, the similarities and the differences between these three procedures, are examined. Some of the theoretical and practical constraints of each method are described in this paper; they must be followed in order to obtain reliable information for agronomic purposes. A method involves measuring the rate of isotopic exchange of phosphate ions in soil-solution systems maintained in steady-state. It is now possible to predict the effectiveness of P fertilizers, whatever their chemical form when this method is applied on soil samples where P fertilizers were applied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00790659
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  • 10
    Electronic Resource
    Electronic Resource
    Sustainable agriculture in the tropics: the case of potassium under maize cropping in Togo (1996)
    Springer
    Nutrient cycling in agroecosystems 46 (1996), S. 205-213 
    Details
    ISSN: 1573-0867
    Keywords: available potassium ; isotopic exchange ; leaching ; maize ; sustainability ; Togo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The transfers of native and applied K in a rhodic Ferralsol were studied in an agrosystem of southern Togo to propose sustainable cultivation strategies for K in kaolinitic soils. Potassium balance was measured over two years in field conditions under continuous maize cultivation with two K fertilisation levels (0 and 137 kg K ha−1 yr−1). Postassium leaching below the root zone, determined using ceramic cup samplers and Darcy's law, was on average 7.5 kg K ha−1 yr−1 with K fertilisation, i.e. 2% of the quantity of K applied, and 4.5 kg K ha−1 yr−1 without. The low leaching values resulted from a K concentration lower than 130 μM in the soil solution. The low K concentration in the soil solution was related to selective adsorption of K increased by a low content of exchangeable K, with a Gapon selectivity coefficient ranging from 7.9 and 11.5 M −0.5. So the level of exchangeable K must first be increased to raise K concentration in the soil solution. The fixation and release of K was analysed using the isotopic exchange method with 42K-ions and compartmental analysis of the kinetics of isotopic exchange. Potassium fixed in a form non available within one year accounted for 78% of the difference between the two treatments. The annual amount of K fertilisation must thus be based on the quantity of K removed in the grain and crop residues, with an extra addition to account for K fixation. Given a crop residue content of 85 kg K ha−1 yr−1 in the fertilised treatment, the return of crop residues is essential if sustainability is to be achieved with traditional cropping systems where little K fertiliser is added.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00420555
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