Abstract
A new type of controlled release fertilizers coated with polyurea was prepared. The granulated urea was firstly changed into a liquid urea by heating as the coating liquid. By spraying uniformly the urea was coated with the polyurea synthesized by the reaction of isocyanates with a liquid urea. The effects of different modifiers on N release characteristics of polyurea-coated urea (PCU) were studied. The morphology and chemical structure of PCU coating materials was investigated by SEM and FTIR. We studied the nitrogen release characteristics of the PCU applied in both water and soil, and the biodegradability of PCU coating after buried in soil. The results showed that PCU reduced nitrogen release rate and exhibited excellent controlled release property. The PCU coating materials could biodegrade in soil. This indicated that the low cost PCU products from urea are expected to use in agricultural and horticultural applications.
Highlights
Fertilizers are one of the most important products in agriculture
Effect of different modifiers on N release characteristics The granulated urea was firstly changed into a liquid urea (LU) to react sufficiently with PAPI
A series of polyurea-coated urea (PCU) were prepared by coating urea with the polyurea synthesized by the reaction of PAPI with a liquid urea to reduce nitrogen release of coated fertilizers
Summary
Fertilizers are one of the most important products in agriculture. Crop yields and growth mainly depend on the use of fertilizers. It was experimentally confirmed that the application of slow-release or controlledrelease fertilizers (CRF), by coating urea granules with materials that exhibit excellent water resisting property, was an effective solution to reduce fertilizer losses and to minimize environmental pollution. Polyurea is a synthetic polymer from isocyanate and amine compound. It has high mechanical strength, excellent film-forming property, high electric energy density and water resistance property, which was utilized for various fields, including composited materials, aerogel, film, coating, microcapsules, dielectric materials, and steel plates (Holzworth et al 2013; Hong and Park 1999; Komurlu and Kesimal 2014; Li et al 2008; Nikishina et al 1989; Wu et al 2014).
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