Briquetted urea is commonly used in wet agricultural soils since it has potential to reduce loss of urea occuring in the fields by various mechanisms. In the present study, commercially available uncoated urea briquettes were subjected to release in wet loam and wet silty clay soils, both maintained at 40% moisture, measured on dry basis. Adapted semi infinite model and developed shrinking core model predictions were compared with the experimentally determined concentration profiles and unreleased quantity of urea, respectively. Semi infinite model developed with the assumption of unchanging briquette size did not match well with experimental results. However, shrinking core model predicted the unreleased urea contents in briquettes reasonably well.
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