Degradable Controlled Release Fertilizer Composite Prepared via Extrusion: Fabrication, Characterization, and Release Mechanisms

Abstract

In this work, biodegradable polymers were melt compounded with urea phosphate to fabricate “smart fertilizers” for sustainable agriculture. Urea phosphate (UP) is typically applied as a water-soluble fertilizer to treat phosphorus deficiency in high pH soils. Due to the low diffusion rate of phosphate through slow-release fertilizer coatings, phosphate supply has been considered the “bottleneck” for nitrogen–phosphorous–potassium (NPK) nutrients supply. We study the influence of polymer matrix structure on release kinetics in deionized water using novel polyesters including poly (hexamethylene succinate) (PHS), poly (30% butylene succinate-co-70% hexamethylene succinate) (PBHS 30/70), and PBHS 70/30. Melt processed composites of UP and polyester were analyzed to determine UP loading efficiency and dispersion and distribution of the salt in the polymer matrix. A combined empirical model involving diffusion and erosion mechanisms was found have a good agreement with the experimental release curve. This work provides a solution for environmentally friendly controlled release phosphate fertilizer with good release performance using bio-based and biodegradable polymers.

Controlled Release Fertilizers: A Review on Coating Materials and Mechanism of Release

“…Synthetic biodegradable aliphatic polyesters are hydrophilic and susceptible to hydrolytic degradation. This was confirmed by Ye et al [ 47 ] and Bi et al [ 48 ] by using different kinds of aliphatic polyesters as the coating material. These studies reported that increasing the size of coated fertilizer while using smaller crystals of urea dispersed in the matrix slows down degradation and the release rate.…”

Incorporation of ZnO Nanoparticles into Soy Protein-Based Bioplastics to Improve Their Functional Properties

“…In this line, Michalik and Wandzinc studied chitosan-based hydrogels [ 9 ]. On the other hand, different nutrients have been incorporated into bioplastic matrices, such as sodium and NPK (primary nutrients: nitrogen, phosphorus and potassium) [ 10 , 11 , 12 ]. There are also examples of controlled release of pesticides, such as the work of Singh et al [ 13 ], who used imidacloprid to release repellent odours for insects and microorganisms.…”

Field-Scale Evaluation of Botanical Extracts Effect on the Yield, Chemical Composition and Antioxidant Activity of Celeriac (Apium graveolens L. Var. rapaceum)

“…However, a steadily increasing demand for synthetic fertilisers has been observed over a few decades. The worldwide consumption of NPK fertilisers is expected to rise from 135.4 million tonnes (Mt) in 2000/2001 to 204 Mt in 2023/2024 [ 5 ]. Nevertheless, the fertilisation effectiveness remains comparatively low, which is caused by the fact that only 50–60% of N [ 5 , 6 ] and K and 10–25% of P are estimated to be utilised by cultivated plants [ 5 ].…”

“…The worldwide consumption of NPK fertilisers is expected to rise from 135.4 million tonnes (Mt) in 2000/2001 to 204 Mt in 2023/2024 [ 5 ]. Nevertheless, the fertilisation effectiveness remains comparatively low, which is caused by the fact that only 50–60% of N [ 5 , 6 ] and K and 10–25% of P are estimated to be utilised by cultivated plants [ 5 ]. Taking this into account, the global demand for N has been expected to reach 107 teragrams (Tg) N per year (with a limit of 50 Tg N reactive not absorbed by plants) by the year 2050 [ 2 ].…”

“…The deficiency of phosphorus induces the increase in H 2 O 2 concentration affecting the cell redox balance due to the increased content of antioxidative enzymes [ 7 ]. On the other hand, a higher fertilisation efficiency can be achieved by using slow/controlled release of nitrogen fertilisers that reduce the loss of N through leaching and evaporation [ 5 ]. Furthermore, the growing dependence on N fertilisers is a major issue in prevailing agriculture practices and has adverse environmental impacts due to several side effects, namely high costs of input and production [ 3 , 4 ], the contribution to the emission of greenhouse gases (up to 70% of the worldwide N 2 O) [ 8 ] and water eutrophication [ 6 ] which is the major threat to biodiversity [ 4 ].…”