Evaluation of a Soil Incubation Method to Characterize Nitrogen Release Patterns of Slow- and Controlled-Release Fertilizers

Abstract

Several technologies have been proposed to characterize the nutrient release patterns of slow-release fertilizers (SRF) and controlled-release fertilizers (CRF) during the last few decades. These technologies have been developed mainly by manufacturers, and are product-specific, based on the regulation and analysis of each SRF and CRF product. Despite previous efforts to characterize SRF and CRF materials, no standardized, validated method exists to assess their nutrient release patterns. However, the increased production and distribution of these materials in specialty and nonspecialty markets requires an appropriate method to verify product claims and material performance. A soil incubation column leaching procedure was evaluated to determine its suitability as a standard method to estimate nitrogen (N) release patterns of SRFs and CRFs during 180 days. The influence of three soil/sand ratios, three incubation temperatures, and four soils on method behavior was assessed using five SRFs and three CRFs. In general, the highest soil/sand ratio increased the N release rate of all materials, but this effect was more marked for the SRFs. Temperature had the greatest influence on N release rates. For CRFs, the initial N release rates and the percentage N released/day increased as temperature increased. For SRFs, raising the temperature from 25 to 35 degreesC increased initial N release rate and the total cumulative N released, and almost doubled the percentage released/day. The percentage N released/day from all products generally increased as the texture of the soil changed from sandy to loamy (lowa>California>Pennsylvania>Florida). The soil incubation technique was demonstrated to be robust and reliable for characterizing N release patterns from SRFs and CRFs. The method was reproducible, and variations in soil/sand ratio, temperature, and soil had little effect on the results.

Nitrogen release from urea with different coatings

“…In contrast, some fertilizers, with characteristics similar to prilled urea, were no longer feasible as slow‐release fertilizers. Moreover, the current results are in agreement with the results from similar studies …”

“…Moreover, the current results are in agreement with the results from similar studies. 13,[24][25][26]…”

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

“…The use of a pure coated product is recommended by the supplier in cases of transplanting seedlings of perennial crops. The results of this study differ from those obtained by Mota (2013) and Medina et al (2014), who used similar incubation conditions on the ground at a temperature of 25 °C and observed the release of 80 to 90 % of the N within 40 to 180 days. Notably, these authors evaluated coated N-fertilizer.…”

“…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.…”

Modeling the Release of Nitrogen from Controlled-Release Fertilizer with Imperfect Coating in Soils and Water

“…They took soil samples from Florida, California, Pennsylvania, and Iowa to analyze the effect of those soils on the release from fertilizer and concluded that the nitrogen release rate increased as soil's texture changed from sandy to loamy. 17 However, in our previous discussion, the release rate of nitrogen decreased as textural class changed from sand to clay. Their results seem to contradict the results from the present work at first glance because the nitrogen release in sand was slower than in silt or clay.…”