Novel water‐soluble polymer coatings control<scp>NPK</scp>release rate, improve soil quality and maize productivity
Mohsan Akhter, Ghulam Abbas Shah, Muhammad Bilal Khan Niazi, Saad Mir, Zaib Jahan, Muhammad Imtiaz Rashid
Abstract
Abstract We investigated different combinations of polymers (5% each) (i) starch, gelatin (polymer coating; PC‐1), (ii) polyvinyl alcohol (PVA), gum Arabica (PC‐2), (iii) PVA, gelatin (PC‐3), (iv) starch, gum Arabica (PC‐4), (v) gelatin, gum Arabica (PC‐5), (vi) starch, PVA (PC‐6), for coating NPK (17, 17:17) in a fluidized bed granulator. Morphological characterization indicated a uniform coating of all formulations on NPK granules. A slow release of N (PC‐3), P (PC‐6), and K (PC‐3) was observed in water. In soil, high mineral N (63%), plant‐available P (72%), and K (24%) were observed in PC‐3, PC‐5, and PC‐6, respectively than uncoated fertilizer. Microbial biomass NPK was also higher in these treatment. This resulted in higher maize yield (66%), N (114%), P (164%), and K (137%) uptakes and apparent N (267%), P (196%), and K (358%) recoveries from applied fertilizer in these treatments. Among these, PC‐3 resulted in an increase of 115% shoot N, 169% P and 138% K uptakes and 268% apparent N, 206% P and 361% K recoveries than uncoated fertilizer. Hence, coating of NPK with this biodegradable polymer combination controlled N, P, and K release and synchronized these nutrients availabilities with maize nutrients demand therefore resulted in higher maize crop yield and nutrient utilization efficiencies.