Macro‐ and micronutrient‐release characteristics of three polymer‐coated fertilizers: Theory and measurements

Abstract

In spite of several published studies we have an incomplete understanding of the ion-release mechanisms and characteristics of polymer-coated fertilizers (PCF). Here we extend current conceptual models describing release mechanisms and describe the critical effects of substrate moisture and temperature on macro-and micronutrient release of three PCF types: Polyon ® , Nutricote ® , and Osmocote ® . Nutrient release was quantified at weekly intervals for up to 300 d from 5°C to 40°C in water and chemically inert sand, substrates that allowed release quantification without confounding effects of ion sorption/desorption. At least two release-timeframe formulations of each PCF type were studied and all products had similar nutrient concentrations to allow isolation of the effect of coating technology. Contrary to several studies, our data and model indicate that there is no significant difference in nutrient-release rates in water and a moist, solid substrate. This means that release rates determined in water can be used to model bio-available nutrient concentrations in moist soil or soilless media where sorption/desorption properties alter concentrations after release. Across all PCF, the nutrients most affected by temperature were typically N, K, B, Cu, and Zn, while the least affected were P, Mg, and Fe. We also found consistent differences among the coating technologies. Osmocote fertilizers released faster than specified at both high and low temperatures. Nutricote had relatively steady release rates over time and a nonlinear response to temperature. Polyon released more slowly than specified but replicate samples were highly uniform.

Application of controlled nutrient release to permeable reactive barriers

“…7b) (Trovati et al, 2010). The aromatic peaks corresponding to symmetric and non-symmetric CeH stretching of diphenylmethane diisocyanate at 2852 cm À1 and 2920 cm À1 showed little discernable change in the presence and absence of toluene (Trovati et al, 2010;Adams et al, 2013). Similar to 3350 cm À1 , the peak in the isocyanate region at 2294 cm À1 demonstrated decreased intensity following exposure to 3.25 mmol/L toluene (Trovati et al, 2010).…”

In Situ Monitoring of a Controlled Release of Fertilizers in Lettuce Crop

“…When studying the behavior for controlled release of coated fertilizers, Adams et al, 2013 observed slow and uniform release for one of the commercial products experimentally tested. On the other hand, in conventional fertilization, there is a greater use of work force for splitting the recommended topdressing dose for crop development.…”

Nutrient Release, Plant Nutrition, and Potassium Leaching from Polymer-Coated Fertilizer

“…High variability (CV 10 to 40 %) in the release of a thermosetting resin-coated fertilizer (NPK) incubated in a liquid medium over 400 days was observed by Adams et al (2013). These authors attributed the problem of uneven release to the coating manufacturing technology based on observation of dilation of the granules and disruption of the coating.…”

“…Studies have been performed in Brazil and abroad using incubation methods in controlled environments to predict the release of nutrients and to evaluate different environmental parameters, such as temperature, moisture, microorganisms, and soil pH and texture (Golden et al, 2011;Adams et al, 2013;Mota, 2013;Medina et al, 2014). Some field Rev Bras Cienc Solo 2017;41:e0160142 studies such as Oosterhuis and Howard (2008) tested slow-release fertilizers N or K coated with polyolefin resin in the US cotton crop.…”