A column perfusion test to assess the kinetics of nutrient release by soluble, sparingly soluble and coated granular fertilizers

Abstract

In recent years, innovations in fertilizer research have principally been in the design of products to supply more timely plant nutrients and mitigate detrimental losses to the environment. In the development of these fertilizers, a laboratory method to comparatively screen a large number of formulations for the rate of nutrient release is a critical first step in formulation optimization to significantly reduce time spent on pot and field trials, reducing costs considerably. Currently, given the absence of a standard laboratory method for all fertilizers, adaptions of a method for coated fertilizers from the International Organization for Standardization (2017) ISO 21263 and other column tests are being used which are often complex and/or require manual sampling which can be laborious, time consuming and costly. The method presented here evaluates the dynamic release in real time by continuously perfusing samples in columns utilizing an automated sample accumulation system for short‐term and long‐term release studies and eliminates the need for soil/sand packing of columns. Mass balance is accounted for by analysing the residue after dissolution and the amount released is expressed as a % of the total nutrient content in the product. This method is reliable, uncomplicated and cost‐effective and has been used to test uncoated soluble fertilizers, nanofertilizers, fertilizers with newly developed coating technologies and other slowly soluble fertilizers, to assess the effect of variables like coating chemistry and thickness, fertilizer composition or fertilizer particle size on release rate.

Mechanochemical Synthesis of Zinc Borate for Use as a Dual-Release B Fertilizer

“…Dissolution kinetic experiments were conducted for nine selected products (Control, 4 h, 8 h, Col + ZnO, TetB + ZnO, Control-S, 4 h-S, 8 h-S, Control-L, and 8 h-L) using the column perfusion method described by Baird et al This is a laboratory method that examines the dynamic release of nutrients from fertilizer formulations by continuously perfusing samples with solution in real time. Previous studies showed good correlation between the pot, leaching, and seeding toxicity experiments using this method. ,, The 4 h-L was not included as no significant changes in other characteristics were observed between 4 h-S and 4 h-L. Powders were used in this study to avoid any potential effects of granulation due to particle size and/or binders.…”

“…Column Dissolution Study. Dissolution kinetic experiments were conducted for nine selected products (Control, 4 h, 8 h, Col + ZnO, TetB + ZnO, Control-S, 4 h-S, 8 h-S, Control-L, and 8 h-L) using the column perfusion method described by Baird et al 38 This is a laboratory method that examines the dynamic release of nutrients from fertilizer formulations by continuously perfusing samples with solution in real time. Previous studies showed good correlation between the pot, leaching, and seeding toxicity experiments using this method.…”

Development and Testing of Improved Efficiency Boron-Enriched Diammonium Phosphate Fertilizers

“…A column dissolution experiment was performed to analyze the release of B and P from the fertilizers using the method described by Baird et al (2019). The (Sigma-Aldrich) glass wool used in the column perfusion test is silanized, which shields active silanol groups on the untreated glass surfaces rendering it hydrophobic to ensure no chemical interactions.…”

Engineered Phosphate Fertilizers with Dual-Release Properties

“…Dissolution Kinetics of P. A column dissolution experiment was performed to quantify the kinetics of the P release from MAP, GO-3Fe-P, Str, MAP-GO-3Fe-P, and MAP-Str using the method of Baird et al 36 Briefly, granules of individual formulations having a total amount of P equivalent to ∼50 mg were placed in a polypropylene column (150 mm × 15 mm) and the column filled with acid-washed glass wool. Deionized water was introduced from the bottom of the column using a peristaltic pump at a constant flow rate (10 mL h −1 ).…”