ABSTRACT
Monitoring phosphorus fertilization is crucial for controlling the concentration of biologically available soil P. Over the years, several methodologies have been used, including successive cropping in a greenhouse or field, as well as extractions employing P sink procedures. The latter procedures are ideal laboratory experiments to show the soil's ability to supply P and to explore the P-residual release kinetics. Following these methodologies, long-term P desorption studies have been developed using dialysis membrane tubes filled with nanomaterial solutions. In this study, a magnetic nanocomposite (Fe3O4/Al2O3/MnO2) was synthesized and characterized utilizing cutting-edge instruments such as XRD, FTIR, FAAS, BET, SEM, and EDX. The resulting material had a crystalline size and surface area of 22.75 nm and 203.69 m2/g, respectively, and was employed for long-term P-desorption and kinetics experiments while filled in dialysis membrane tubes. The P-desorption experiment was conducted on four separate acidic soil samples that were cultured for 122 days with four different P concentrations. The findings demonstrated a direct relationship between P-desorbed and P-treatment, as well as with desorption time. The minimum desorption was obtained from the control of Boji Dirmaji soil P0 (1.16-9.36) and the highest desorption from Nedjo soil with P3 (5.23-30.35 mg/kg) treatment over 1-28 days. The rate of P release from soil to solution or diffusion through the membrane was determined by pseudo-first-order kinetics with a rate constant (0.021-0.028 hr-1). This method has the potential to measure fixed-P availability by mimicking it as a plant would, with high P-desorption efficiency and quick P-release capacity.
ABSTRACT
Excessive use of chemical fertilizers causes serious environmental hazards, as only a fraction is really adsorbed by the soil. As part of the solution, the feasibility of using unmodified (UNZC) and surfactant-modified natural zeolite-based composite (SMNZC) fertilizers as support materials for the provision of nutrients to soil on a slow release basis was assessed using column and pot experiments. The characterization of the zeolite materials was done using powder XRD, XRF, SEM, BET, and TGA instruments. The percentage of cationic nutrients released from soil columns containing UNZC increased over time. Their release from SMNZC initially slowed down and became stable as the number of days increased. The percentage of N-NO3- and available P released from UNZC has constantly decreased with time. Their release from SMNZC increased as the number of days increased. The maximum P uptake by maize was observed for the soil treated with SMNZC, and there was no significant difference at all rates. The maximum uptake of Ca (3663.40 ppm), Mg (2617.34 ppm), and Fe (222.83 ppm) was observed at 250 kg/ha of UNZC. The highest uptake of K, Zn, and Cu was also observed for the soil amended with UNZC, irrespective of its application rate. Application of UNZC and SMNZC at the same rate equally affected total nitrogen uptake. Thus, this finding showed that UZNC is a better carrier of cationic nutrients, while SMNZC is preferable for the slow release of NO3- and available P. In conclusion, both the modified and unmodified support forms showed better performance than conventional fertilizer in delivering nutrients slowly and sustainably.
