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  • 1
    Electronic Resource
    Electronic Resource
    Effect of timing of application of municipal solid waste compost on N availability for crops in central Spain (1997)
    Springer
    Biology and fertility of soils 25 (1997), S. 136-141 
    Details
    ISSN: 1432-0789
    Keywords: Key words Incubation ; N mineralization ; Municipal solid waste compost ; Simulation models ; N availability ; Maize ; Mineralization kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To calculate the correct nitrogen fertilizer rate for crops and the possibility of using municipal solid waste (MSW) compost as an organic amendment, nitrogen mineralization rates were studied by laboratory incubation and field measurements in a soil in central Spain. Nitrogen mineralization rates were studied in a 250-day laboratory soil incubation with two treatments: with and without compost, incubated at 28°C and a moisture content of 70% of field capacity. Three phases are described: (1) no increase in the mineral nitrogen content, (2) a linear increase in the mineral N fraction and, finally, (3) a linear, parallel increase in both mineral N and easily mineralizable organic N fractions. Incubation data were fitted to three different equations. The exponential model proposed by Stanford and Smith (1972) was selected to predict field N mineralization rates. The field experiment was performed using a crop of maize with three treatments: compost applied in February (before sowing), compost applied during sowing and a control (without compost application): sampling was carried out over 14 months. Soil water content was measured periodically. Soil with compost applied in February showed 1.9 and 1.4 times more available nitrogen than soil without compost and compost at sowing, respectively, for the month of maximum accumulation. These results suggest that compost amendments must be applied before sowing. Compost applications were shown to supply the available nitrogen for spring crops. A simulation model showed satisfactory agreement with field data, after correction for soil temperature and water content.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050293
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  • 2
    Electronic Resource
    Electronic Resource
    Free expansion of a gas against a rigid wall (1989)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 1 (1989), S. 285-288 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The flow behind the shock wave produced when a freely expanding gas strikes a rigid wall is studied. The shock speed is known within an early stage after the shock onset, when the flow is self-similar and, also, as is pointed out, when the shock decays into a sonic disturbance, propagating in an almost uniform gas. On this basis, an approximate differential equation can be written for the shock position, whose solution is analytic, and therefore, the flow magnitudes are given by simple relationships. Comparison with numerical simulations shows that the flow is well described by this approximation. This work also includes a brief review of the equations for the self-similar regime, because corrections to previously published results were found necessary.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.857444
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  • 3
    Electronic Resource
    Electronic Resource
    Acceleration of a slab driven by a constant pressure piston (1989)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 1 (1989), S. 1426-1429 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The sequence of shock and rarefaction waves, which occur in a plane layer of ideal gas initially at rest when it is driven toward the vacuum by a very high constant pressure piston, is studied. In the rarefaction flow that relaxes the layer compressed by the first strong shock, a second shock is generated. The time and position of its formation are obtained by an exact analytical expression. The subsequent motion and intensity of the shock wave are approximated by the Chester–Chisnell–Whitham (CCW) method. Then, the Lagrangian distribution of entropy in the layer is analytically derived.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.857320
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  • 4
    Electronic Resource
    Electronic Resource
    Laplace pressure driven drop spreading (1994)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 6 (1994), S. 24-33 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This work concerns the spreading of viscous droplets on a smooth rigid horizontal surface, under the condition of complete wetting (spreading parameter S(approximately-greater-than)0) with the Laplace pressure as the dominant force. Owing to the self-similar character foreseeable for this flow, a self-similar solution is built up by numerical integration from the center of symmetry to the front position to be determined, defined as the point where the free-surface slope becomes zero. Mass and energy conservation are invoked as the only further conditions to determine the flow. The resulting fluid thickness at the front is a small but finite (≈10−7) fraction of the height at the center. By comparison with experimental results the regime is determined in which the spreading can be described by this solution with good accuracy. Moreover, even within this regime, small but systematic deviations from the predictions of the theory were observed, showing the need to add terms modifying the Laplace pressure force.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.868072
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of sewage sludge on nitrogen availability in peat (1992)
    Springer
    Biology and fertility of soils 13 (1992), S. 248-251 
    Details
    ISSN: 1432-0789
    Keywords: Sewage sludge ; Peat ; N availability ; Electro-ultrafiltration ; Liming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary We studied the effect of incubating peat with lime and sewage sludge in small proportions on biological activity and N mineralization. The peat response was dependent on pH and, in acid peats, on mineralization capacity. In acid peats, the addition of sewage sludge inhibited biological activity. Only the most eutrophic peats (Herbosa) responded with accelerated mineralization. The addition of lime to acid peats favoured organic matter mineralization, shown by a greater CO2 release. The best results were obtained by adding lime and sewage sludge together. In saline peats, the best N levels were obtained without incubation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00340584
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  • 6
    Electronic Resource
    Electronic Resource
    Control of nitrate pollution by application of controlled release fertilizer (CRF), compost and an optimized irrigation system (1995)
    Springer
    Nutrient cycling in agroecosystems 43 (1995), S. 191-195 
    Details
    ISSN: 1573-0867
    Keywords: nitrate leaching ; pollution ; fertilizer ; irrigation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A nitrogenous controlled release fertilizer (Floranid 32) and a treatment of municipal organic waste compost were tested under two irrigation managements (conventional and ET-adjusted irrigation rates) with the aim of assessing risk of nitrate leaching to the aquifer. A check without N fertilizer was introduced. The experiment was carried out at La Poveda Field Station (30 km SE Madrid, Spain) in alluvial soils with water table depth at 4 m and under maize cropping. The experiment was laid out in a randomized complete block design with three replications, allocating 12 plots to each irrigation management. Although N fertilizer rate (150 kg ha−1) was reduced at half as related to a previous experiment, no difference in grain yields was observed. This result relates to a high content of soil-N. Floranid showed promising results in controlling N-leaching in comparison with urea that exhibited an accelerated rate of N release which finally determines low use of N by the plant and marked NO3 − leaching. Treatment of municipal waste compost showed NO3 − concentrations in the soil water solution of similar values as those of urea at 140 cm. ET-adjusted irrigation showed no drainage during the corn growing season and lower NO3 − concentrations in the soil water solution which could indicate a general lower rate of N solubilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00747701
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  • 7
    Electronic Resource
    Electronic Resource
    Nitrogen availability of soluble and slow release nitrogen fertilizers as assessed by electroultrafiltration (1993)
    Springer
    Nutrient cycling in agroecosystems 34 (1993), S. 121-126 
    Details
    ISSN: 1573-0867
    Keywords: Controlled release fertilizers ; electroultrafiltration ; nitrogen ; ryegrass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The efficiency of different nitrogenous fertilizers under forced leaching conditions was determined in pot experiments using ryegrass as an indicator plant in a sandy loam soil. Treatments were: ON (unfertilized), AN (ammonium nitrate), U (urea), DAP (diammonium phosphate), T (Triabon), FK (Floranid Komplett) and CDU (crotonylidendiurea). N source effects on N uptake, and N leached (as % of N applied) were evaluated. Results show that the fertilizers which behaved best with regard to N uptake were FK followed by Triabon and AN. The most soluble fertilizers, AN and urea, gave the highest N leaching losses. Significant correlations between EUF-NI (rapidly soluble fraction) and leaching, as well as between EUF-N (I + II) and N uptake by the plant (where EUF-N II relates to the slowly soluble fraction) were obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750106
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  • 8
    Electronic Resource
    Electronic Resource
    Controlling phosphorus fixation in calcareous soils by using coated diammonium phosphate (1992)
    Springer
    Nutrient cycling in agroecosystems 31 (1992), S. 269-274 
    Details
    ISSN: 1573-0867
    Keywords: Phosphorus fixation ; calcareous soils ; coated fertilizer ; diammonium phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In this paper, phosphorus fixation in calcareous soils is controlled by means of rosin-coated diammonium phosphate pellets, with several rates of phosphorus release. Four soils from arid regions in the Spanish south-east were chosen and separately treated with one of the following fertilizers: superphosphate (SP) or diammonium phosphate (DAP) coated with 0, 10 or 22% rosin with a dosage of 1000 Kg P/ha. After treatment, the soils were incubated for 8 months, in the course of which samples were taken to evaluate the evolution of P availability by means of the electroultrafiltration (EUF) technique. The results obtained show that the use of DAP with a 22% coating enables phosphorus fixation in calcareous soils to be controlled. The coating was sufficiently stable to last for the time it takes the crop to grow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01051278
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