Establishing a Viable Fertilizer Quality Detection System

The proof of concept project entitled “Establishing the Viability of a Fertilizer Quality Detection System Using Alternative Analytical Technology (FAAT)” is aimed at developing a quick and robust methodology to determine the nutrient content in fertilizers. The methodology comprises the use of circular paper chromatography (CPC) and digital characterization of the corresponding chromatographic images incorporated in a database for automated assessments. One hundred (from the United States) and 22 (from India) different types of fertilizers were procured from the United States and India, and their nutrient properties were analyzed following conventional methods. These fertilizer samples were further diluted in 100 mL of 1% NaOH to obtain 3800 fertilizer concentrations. For the Indian fertilizers, 2200 samples were obtained with all 22 fertilizers by generating 100 different samples in incremental dilutions of 0.050g, up to 5 g. For the IFDC fertilizers, 1600 samples were similarly obtained from 80 of the 100 fertilizers, diluted up to 1 g. These fertilizer concentrations were analyzed using CPC. Three databases were created to serve as reference, comprising (i) the Indian fertilizer database with 1500 reference fertilizer sample images, (ii) the IFDC database with 563 samples and (iii) a combined database of 2063 samples. Finally, an unknown fertilizer chromatographic image from unknown fertilizer sample types was used for testing the accuracy of the methodology by comparing the chromatographic images with the images contained in the reference databases. Out of the 25 test samples from IFDC, 21 reported similarity between AAT methodology and conventional analytical methods for nutrient content determination, and hence on quality, implying that 84% were mimicked correctly. Out of the 18 fertilizers from India, 11 tested correctly when using the database with 1500 references, representing about 61% accuracy of retrieving the correct fertilizer type and quality. The consolidated database containing both IFDC and Indian fertilizer (2063) was tested and recorded 34 out of 43 test samples that were similar between the FAAT system and conventional analytical methods, indicating about 70% accuracy. The existing AAT software was fine-tuned and integrated as unique stand-alone software for the FAAT system and used for fertilizer testing. An investigation was also carried with two types of fertilizers: urea and single superphosphate (SSP), and deliberately adulterating them with low grade inputs. The urea fertilizer was adulterated with ammonium sulfate (AS) and single superphosphate in the ratios of 1:0, 1:1, 1:3 and 3:1. The adulterated fertilizers were blended using mortar and pestle and 0.500g and 1.000 g were taken for CPC image development. Both the urea fertilizer and SSP were adulterated with AS and gypsum and tested on the FAAT system based on CPC images. The adulterated samples were retrieved from the data base and indicated 100% and 71% accuracy, respectively. Our study shows that with further refinement, the use of AAT methodology for testing fertilizer nutrient content and the presence of contaminants, and hence quality of the fertilizer, is a promising technology.
Nutrients, Fertilizers
Perumal, K., Ananthi, S., Arunkumar, J., Sambanda Moorthy, T.A., Karthik, B., U. Singh, and P.S. Bindraban, 2013. Establishing a Viable Fertilizer Quality Detection System, VFRC Report 2014/4. Virtual Fertilizer Research Center, Washington, D.C. 23 pp.; 9 tables; 3 figs.; 8 ref.