The Potential and Efficiency of Nano-K Coated Diammonium Phosphate (DAP) to Improve Crop Yield

Abstract

Alarmingly low use efficiency of nitrogen and phosphatic (P) fertilizers, imbalance use of NP fertilizers and intensive cropping to feed ever increasing population has disturbed potassium (K) balance causing 20-40% K deficiency in Pakistani soils. The nanotechnology with the idea of enhanced bioavailability, reactivity, surface area and adhesive effect of nano materials has made it a revolutionary tool for enhanced crop growth. The research was done with the objective i) to synthesize & characterize the potassium ferrite nanoparticles (KFeO2 NPs) and coating on diammonium phosphate (DAP) fertilizer ii) evaluate the slow release of mineral N, P, K and Fe from coated DAP in two different textured soils iii) check the efficacy of coated DAP on growth attributes and yield contributing parameters. In first study, the KFeO2 NPs were prepared and characterized using different advanced techniques of X-ray diffraction (XRD) and scanning electron microscope (SEM). The results confirmed the orthorhombic structure of nano particles, metal bonds formation between iron (Fe) and potassium (K) and particles size range between 7-18nm. In the second study, four treatments i.e. uncoated DAP and coated DAP @ 2, 5 and 10 % were applied to soil under controlled conditions. The results indicated the slow and controlled release of P and NO3 -1 -N and maximum addition of K and Fe in the soil where 10% coated DAP was employed. In the third study, nine different treatment combinations of nano-coated DAP fertilizers on wheat growth and yield were tested in pots. The results clearly depicted highest grain and straw yield in treatment coated DAP @ 10 % followed by coated DAP @10 % (75% RD+ 25%K). The grain yield was significantly better than the NPK and NP treatments. Finally, a field study was conducted with seven best performed treatments selected from study 3. The results showed that plant height, shoot fresh and dry weight, chlorophyll content, N, P K, and Fe content in shoot (at tillering and booting stage) and in grains and straw were significantly higher in 10% coated DAP and it also showed significantly better grain and straw yield than all other coated and uncoated treatments. The treatment NP (RD NP from DAP, urea + no potassium showed the least performance in growth parameters, yield attributes and harvest index. It was concluded from the entire plan of study that nano coated DAP was a practical approach to be applied for enhanced and prolonged nutrient (N, P, K and Fe) efficiency and plant growth concomitantly yield attributes of wheat crop.