Novel low-cost carboxymethyl cellulose microspheres with excellent fertilizer absorbency and release behavior for saline-alkali soil.

Saline-alkali soil and fertilizer loss severely restrict agriculture on the Songnen Plain in China. To resolve this problem, carboxymethyl cellulose immobilized slow-release fertilizer microspheres (CFM) with homogeneity pore structure, high porosity, biodegradable biological macromolecules and excellent fertilizer absorbency were synthesized by the combination of inverse emulsion polymerization and microfluidic method. By optimizing the synthesis conditions, the water absorption of CFM reached 8725 g g-1 in deionized water. The absorbency behaviors of CFM were highly sensitive to pH, ionic strength, and ionic species. In 5 g L-1 urea solution, the adsorption capacity of CFM was 3342.84 g g-1. The CFM showed excellent urea retention at 80 °C for 5 h and sustained release performance in soil. Besides, degradation rate of CFM was closed to 98.2% in Aspergillus niger at the third day. CFM had the advantages of high pH sensitivity, salt resistance, and good fertilizer absorbency and retention. Therefore, it will be prospecting fertilizer sustained release agent in agriculture.