Fig. 7: Slow-release fertilizer (SRF) preparation and nutrient release behavior.

A Preparation flowchart of granular SRF using the Product and attapulgite (ATP), digital images of SRF in a water immersion system and time-dependent 3D-EEM spectra variation of the aqueous solution within 30 days. Release curve of (B) FLA and (C) K+ during 30 days water immersion of SRF. D FTIR spectra, (E) scanning electron microscopy (SEM) images, and (F) XRD spectra of SRF before and after slow-release. Experiments were performed three times independently with similar results. Error bars in (B, C) represent the standard deviations from triplicate tests (n = 3). Data are presented as mean values ± s.d. Source data are provided as a Source Data file.