Biodegradable polyurethane materials from bark and starch. II. Coating material for controlled‐release fertilizer

Abstract

Biodegradable polyurethane foams (PUFs) as coating materials for the controlled release of fertilizer were prepared from a four-component system consisting of diisocyanate, polyester, Acacia mearnsi bark, and corn starch. Ammonium sulfate [(NH 4 ) 2 SO 4 ] was used as a fertilizer to evaluate the effects of the preparation conditions on the release ratio. The release ratio of (NH 4 ) 2 SO 4 decreased with an increasing amount of biomass in PUFs and increasing sizes of sample particles; the ratio increased with increasing doses of water, which was used as a foaming agent in the preparation of polyurethane, regardless of the amount of coating material. The remaining fertilizer in the polyurethane seemed to be released completely because the PUFs were degradable, to some extent, by soil microorganisms.

Preparation and properties of a slow release NP compound fertilizer with superabsorbent and moisture preservation

“…[1][2][3][4] A great deal of research has shown that slow or controlled release technology could effectively check these problems, avoiding or decreasing the loss of normal fertilizers and the environmental pollution. 5,6 At the same time, many farmlands in the world are short of water during the dry season, and most of the rainwater was lost in the rainy season because the water resource could not be used efficiently. Superabsorbent polymers, a new functional polymer material, can absorb a large amount of water and the water is hardly removed even under pressure, and so it has been widely used in agriculture.…”

Polymers and its applications in agriculture

“…Several reviews with reference to degradation processes of polymers in soil and aqueous medium have been published [101,102] . However, few discussions have accomplished polymer degradation from agrochemicals encapsulated in a polymer matrix.…”

“…Nevertheless, few works have dealt with the relationship between polymer applications in agriculture and their biodegradation in soils under natural conditions. Ge et al [101] used biodegradable polyurethane as ammonium sulfate fertilizer coating and subsequent biodegradation studies were performed. They suggested that the contribution of the PU matrix on the initial release stage occurs by the diffusion process and an additional release is associated with degradation in the last stage.…”

Cloreto de potássio revestido em efeito residual no feijoeiro de inverno irrigado na região de cerrado

“…As principais inovações estão na recomendação de doses de acordo com a produtividade esperada, influência do tipo de solo, manejo, época de semeadura e material genético DUARTE, 2004 (GE et al, 2002;SHAVIT;REISS;SHAVIV, 2002).…”