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Residual effect of long-term applications of farmyard manure to silage maize (1990)

Dilz, K. ; Postmus, J. ; Prins, W. H.

Springer

Nutrient cycling in agroecosystems 26 (1990), S. 249-252

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ISSN: 1573-0867

Keywords: Long-term manure trial ; residual effect ; model test ; nitrogen availability ; maize ; Italian ryegrass

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Sluijsmans and Kolenbrander developed a simple model to describe the availability of animal manure, assuming a readily available, an easily decomposable and a slowly decomposable N fraction. We tested this model on data from an experiment in which farmyard manure had been applied for eleven successive years to silage maize [Zea mays L.] grown on a light sandy soil. The residual effects of this FYM were then measured by growing Italian ryegrass [Lolium multiflorum Lamk.] in the 12th year. The measured uptake of N by the grass of the FYM residues was then compared with the computed values. The measured amounts of N taken up agreed fairly well with the calculated amounts for applications of 50 and 100 t FYM per ha per year. If the rates of manure application are adjusted to crop requirement, the model shows that the potential, long-term release of N from the residual N fraction of FYM will not exceed 20 kg N per ha. For cattle slurry with a smaller residual fraction, the release will be at most 10% of the total annual N application.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01048763

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Numerical calculation of wall-to-bed heat-transfer coefficients in gas-fluidized beds (1992)

Kuipers, J. A. M. ; Prins, W. ; Van Swaaij, W. P. M.

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 38 (1992), S. 1079-1091

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ISSN: 0001-1541

Keywords: Chemistry ; Chemical Engineering

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology

Notes: A computer model for a hot gas-fluidized bed has been developed. The theoretical description is based on a two-fluid model (TFM) approach in which both phases are considered to be continuous and fully interpenetrating. Local wall-to-bed heat-transfer coefficients have been calculated by the simultaneous solution of the TFM conservation of mass, momentum and thermal energy equations. Preliminary calculations suggest that the experimentally observed large wall-to-bed heat-transfer coefficients, frequently reported in literature, can be computed from the present hydrodynamic model with no turbulence. This implies that there is no need to explain these high transfer rates by additional heat transport mechanisms (by turbulence).The calculations clearly show the enhancement of the wall-to-bed heat-transfer process due to the bubble-induced bed-material refreshment along the heated wall. By providing detailed information on the local behavior of the wall-to-bed heat-transfer coefficients, the model distinguishes itself advantageously from previous theoretical models. Due to the vigorous solids circulation in the bubble wake, the local wall-to-bed heat-transfer coefficient is relatively large in the wake of the bubbles rising along a heated wall.

Additional Material: 14 Ill.