Characteristics of slow- and controlled-release fertilizers and their agrnomic and environmental effects: a short review

Globally, the demand and use of mineral fertilizers is increasing to ensure crop production.Mineral fertilizers supply essential plant nutrients for crop growth, but inappropriate or excess use of the fertilizers causes nutrients loss in the soils and negative impacts on the environment, resulting socio-economic concerns.Accordingly, there is a demand for cultivation technology that improves the nutrient use efficiency of crops while minimizes environmental load, and one of the alternatives to this demand is to develop slow-or controlled-release fertilizers (SRF or CRF).This paper presents a review of literature of SRF and CRF related to crop growth, nutrient use efficiency (NUE), non-point source pollution, and greenhouse gas (GHG) emission.The aim of the current review is to develop technical understanding of the conventional slow-and controlled-release fertilizers and associated with the release mechanisms for crop growth.The fertilizers can be classified into two types, controlled-release fertilizers by physical phenomenon of osmosis and diffusion and slow-release fertilizers by microbial or chemical decomposition in soils.And the nutrient release of the fertilizers can be controlled depending on the properties and physical characteristics of coating materials.In general, SRF or CRF releases nutrients in linear, parabolic, and sigmoidal forms.The most ideal form is the sigmoidal that matches the crop nutrient demand, thereby improves NUE and crop productivity and reduces non-point source pollution and GHGs emission over the growing season.