Produção de fertilizante nitrogenado revestido com polímeros PVA e alginato e estudo da aplicação na cultura do milho

Abstract

The use of nitrogen fertilizers is large and has some problems due to nitrogen loss to the environment by volatilization, leaching or breaking action of urea molecule by enzymes in the soil which leads to degradation by soil conditions, making it impossible for the plant to absorb the nutrient. Studies show that about 50% of nitrogen is lost in the superficial application of urea. Controlled release fertilizer production is an alternative to prevent such losses and increase productivity. The use of biodegradable polymers has been increasingly studied as in the case of PVA and Alginate (AS). In this work the use of these materials occurred with the crosslinking with the divalent calcium and zinc ions. In addition, a test was performed with the use of urea-interspersed kaolinite in order to verify the feasibility of their use. due to the possibility of cross-linking as well as the formation of an interpenetrating network, which hinders the solubilization of urea in moisture, as well as being biodegradable and not affecting plant development. The formulation used in this work has no studies, which makes the work innovative. Fertilizer production was by low temperature cross-linking followed by drying in an air circulation oven. After the release test in extreme environment (immersed in water) was performed, the characterization and application in corn crop. The release tests obtained good results with all samples containing nitrogen in the samples after 96 hours of release, especially PVAASZnS60 with final retention of 16.01%, followed by PVAASKIU 13.01%, PVAASCaZn60 with 10.98%. and PVAASZnN60 with 10.09%. In the characterization, the crystallinity of the zinc ion crosslinked samples stands out in comparison with the calcium, in all the samples the urea peak was presented and as the crosslinker ion its characteristic peak. In infrared, it is noteworthy that the gradual increase in urea content did not change the characteristics of the fertilizer produced, it is observed that the higher the urea content the bands of the 3500cm-1 region had an enlargement. Thermogravimetric analysis (TG, DTG) showed that the urea coating provided greater thermal stability, providing a greater number of mass loss events and is an important data to avoid volatilization losses, the more heat resistant the less will be lost. nitrogen at more extreme temperatures. The result of the application in corn culture was satisfactory, since all samples had higher dry mass than the sample with commercial urea, especially the samples crosslinked with zinc ion. The samples PVAASCaZn60 and PVAASZnN60 had the highest agronomic efficiency, surpassing the commercial urea. This demonstrates the possibility of developing a controlled release fertilizer achieving the objective of this work, producing a controlled release fertilizer with better agronomic efficiency than conventional urea.