Biodegradable polymer based coated controlled release fertilisers
Sumedha Amaraweera, PhD student
School of Chemical Engineering, The University of Queensland
The quality of the soil or land is diminishing due to land degradation, industrialisation, desertification, and urbanisation. Therefore, agricultural lands need agrochemicals such as fertilisers, inhibitors, and pesticides to maintain food demand and security, particularly in light of a growing population. Fertilisers, which can be organic or inorganic, enhance crop yield and are essential macronutrients in today’s agriculture. The most common inorganic fertilisers are urea, potash, phosphate, and compound fertilisers, which consist of more than one type of inorganic fertiliser. Urea is the most widely used nitrogen fertiliser because of its low cost compared to ammonium nitrate. However, the high rate of nitrogen released by urea causes plants to burn. Being highly soluble, it is also very inefficient, with >50% N losses through dissolution and leaching, as well as and other issues such as soil erosion and greenhouse gas emission due to nitrous oxides etc. Loss of nutrients also causes significant economic loss and health problems.
Enhanced efficiency fertilisers (EEFs) slowly release the active ingredients over time, resulting in enhanced nutrient use efficiency and crop yield. Due to the use of EEFs, the application rate can be reduced by 20-30 %, which saves labour, time, money, and energy by providing economic benefits. However, some EEFs have disadvantages. For example, sulphur-coated urea increases soil acidity, and non-degradable polymer-coated fertilisers leave microplastics accumulating in the soil, contributing to another environmental problem. Therefore, the development of alternative biodegradable renewable, and nontoxic coatings is required. This project aims to develop biodegradable polymer-based urea fertilisers and to characterise the urea release profiles in different environments.
Video of biodegradable polymer coated urea granules. Video was constructed using Micro CT.
