Role of Slow-Release Nanocomposite Fertilizers on Nitrogen and Phosphate Availability in Soil

Developing efficient crop fertilization practices has become more and more important due to the ever-increasing global demand for food production. One approach to improving the efficiency of phosphate and urea fertilization is to improve their interaction through nanocomposites that are able to control the release of urea and P in the soil. Nanocomposites were produced from urea (Ur) or extruded thermoplastic starch/urea (TPSUr) blends as a matrix in which hydroxyapatite particles (Hap) were dispersed at ratios 50% and 20% Hap. Release tests and two incubation experiments were conducted in order to evaluate the role played by nanocomposites in controlling the availability of nitrogen and phosphate in the soil. Tests revealed an interaction between the fertilizer components and the morphological changes in the nanocomposites. TPSUr nanocomposites provided a controlled release of urea and increased the release of phosphorus from Hap in citric acid solution. The TPSUr nanocomposites also had lower NH(3) volatilization compared to a control. The interaction resulting from dispersion of Hap within a urea matrix reduced the phosphorus adsorption and provided higher sustained P availability after 4 weeks of incubation in the soil

Hydrogels: An Effective Tool to Improve Nitrogen Use Efficiency in Crops

Hydrogels are hydrophilic polymeric materials with three-dimensional(3D) network structures physic and/or chemically crosslinked. They can absorb large amounts of water or aqueous solutions for a short period of time. When the hydrogel is loaded with a drug and meets an aqueous medium, the water penetrates the system and dissolves the drug. To improve the nitrogen use efficiency by plants, controlled release fertilizers are developed with hydrogels as matrices. In particular, biodegradable polymers such as starch, xanthan, chitosan, cellulose derivatives, pectin and their mixtures have been essayed to avoid residues in soils. In addition, the superabsorbent capacity of the hydrogels improves the retention of fertilizers in the soil, reduces water losses through evaporation and decreases the frequency of irrigation.In this chapter, the behavior of different hydrogels to improve the availability of nitrogen by the plants during their crop cycle will be reviewed.Fil: Melaj, Mariana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología en Polímeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología en Polímeros y Nanotecnología; ArgentinaFil: Giménez, Rocío Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología en Polímeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología en Polímeros y Nanotecnología; Argentin