Constructing Slow-Release Formulations of Ammonium Nitrate Fertilizer Based on Degradable Poly(3-hydroxybutyrate)

The present study describes construction and investigation of experimental formulations of ammonium nitrate embedded in a matrix of degradable natural polymer poly-3-hydroxybutyrate [P(3HB)] and P(3HB) blended with wood flour shaped as tablets, some of them coated with P(3HB). Kinetics of ammonium release into soil as dependent on the composition of the polymer matrix was investigated in laboratory experiments. The rates of fertilizer release from formulations coated with a biopolymer layer were considerably (two months or longer) slower than the rates of fertilizer release from uncoated formulations, while release from polymer and composite (polymer/wood flour) formulations occurred with comparable rates. The use of the experimental formulations in laboratory ecosystems with wheat (Triticum aestivum L.) was more effective than application of free ammonium nitrate. The advantage of the slow-release fertilizer formulations is that they are buried in soil together with the seeds, and the fertilizer remains effective over the first three months of plant growth. The use of such slow-release formulations will reduce the amounts of chemicals released into the environment, which will curb their accumulation in food chains of ecosystems and mitigate their adverse effects on the biosphere.