| Autor: |
da Cruz DF; Instituto de Química de São Carlos (IQSC), Universidade de São Paulo (USP) , Campus de São Carlos, Avenida Trabalhador São-Carlense 400, Caixa Postal 780, Arnold Schimidt, São Carlos, São Paulo 13566-590, Brazil., Bortoletto-Santos R; Laboratório Nacional de Nanotecnologia para o Agronegócio (LNNA), Embrapa Instrumentação , Rua 15 de Novembro 1452, Centro, São Carlos, São Paulo 13560-970, Brazil., Guimarães GGF; Laboratório Nacional de Nanotecnologia para o Agronegócio (LNNA), Embrapa Instrumentação , Rua 15 de Novembro 1452, Centro, São Carlos, São Paulo 13560-970, Brazil., Polito WL; Instituto de Química de São Carlos (IQSC), Universidade de São Paulo (USP) , Campus de São Carlos, Avenida Trabalhador São-Carlense 400, Caixa Postal 780, Arnold Schimidt, São Carlos, São Paulo 13566-590, Brazil., Ribeiro C; Laboratório Nacional de Nanotecnologia para o Agronegócio (LNNA), Embrapa Instrumentação , Rua 15 de Novembro 1452, Centro, São Carlos, São Paulo 13560-970, Brazil. |
| Abstrakt: |
The coating of fertilizers with polymers is an acknowledged strategy for controlling the release of nutrients and their availability in soil. However, its effectiveness in the case of soluble phosphate fertilizers is still uncertain, and information is lacking concerning the chemical properties and structures of such coatings. Here, an oil-based hydrophobic polymer system (polyurethane) is proposed for the control of the release of phosphorus from diammonium phosphate (DAP) granules. This material was systematically characterized, with evaluation of the delivery mechanism and the availability of phosphate in an acid soil. The results indicated that thicker coatings can change the maximum nutrient availability toward longer periods, such as 4.5-7.5 wt % DAP coated, that presented the highest concentrations at 336 h, as compared to 168 h for uncoated DAP. In contrast, DAP treated with 9.0 wt % began to increase the concentration after 168 h until it results in maximum release at 672 h. These effects could be attributed to the homogeneity of the polymer and the porosity. The strategy successfully provided long-term availability of a phosphate source. |
