In-situ production of amino acid-rich monoammonium phosphate from chicken feathers provides superior efficacy compared to physical blending.

A large amount of feather waste is discarded annually, leading to severe environmental pollution problems. Meanwhile, to improve the utilization efficiency of phosphate fertilizers, this study utilized wet-process phosphoric acid (WPPA) to hydrolyze feathers in-situ, producing ammonium amino acid phosphate (AAMAP), and set up physically mixed ammonium phosphate (ARMAP) as a control. The application effects of AAMAP and ARMAP produced under different conditions on bok choy growth were investigated. The results showed that AAMAP consistently outperformed ARMAP in promoting yield, with fresh weight and dry weight increases ranging from 1.38 % to 26.06 % and 5.69 % to 20.67 %, respectively. Among all treatments, the AAMAP (150 g/L-3) group was the most effective, increasing fresh weight and dry weight by 37.13 % and 46.13 % compared to the blank control group. Analysis revealed that the superior application effect of AAMAP was attributed to the elimination of the water-insoluble NH4MgPO4·H2O crystals due to amino acid chelation, leading to improved phosphorus and magnesium utilization, as well as the formation of phosphoesters. Furthermore, economic analysis showed that the addition cost of AAMAP was only 28.52 % of ARMAP. This method of utilizing WPPA to hydrolyze feathers in-situ for AAMAP production is an economical and effective approach to treat feather waste and enhance the utilization efficiency of phosphate fertilizers.

Treatment of distiller grain with wet-process phosphoric acid leads to biochar for the sustained release of nutrients and adsorption of Cr(VI).

Soil amendment products, such as biochar, with both sustained nutrient release and heavy metal retention properties are of great need in agricultural and environmental industries. Herein, we successfully prepared a new biochar material with multinutrient sustained-release characteristics and chromium removal potential derived from distiller grain by wet-process phosphoric acid (WPPA) modification without washing. SEM, TEM TG-IR, in situ DRIFTS and XRD characterization indicated that biochar and polyphosphate formed simultaneously and were tightly intertwined by one-step pyrolysis. The optimal product (PKBC-400) had the most stable carbon structure and an adequate P-O-P structure with less P loss. Batch experiments illustrated that 92.83% P (ortho-P), 85.94% K, 41.49% Fe, 78.42% Al and 65.60% Mg were continuously released in water from PKBC-400 within 63 days, and the maximum Cr removal rate reached 83.57% (50 mg/L K2Cr2O7, pH=3.0) with an increased BET surface area (304.0557 m2/g) after nutrient release. SEM, IC and 31P NMR analyses revealed that the dissolution and hydrolysis of polyphosphates not only realized the sustained release of multiple nutrients but also significantly improved the sustained release performance. The proposed resource utilization strategy provided new ideas for Cr hazard control, biomass waste utilization and fertilizer development.

Solid-Liquid Phase Equilibrium of Ammonium Dihydrogen Phosphate and Agricultural Grade Ammonium Polyphosphate (Degree of Polymerization Ranging from 1 to 8) for Mixed Irrigation Strategy.

Water-soluble ammonium polyphosphate (APP) has the advantages of good solubility and slow-release characteristics and has the potential to be used in combination with monoammonium phosphate (MAP) as a high phosphorus content slow-release fertilizer to improve the utilization rate of phosphorus during irrigation. Herein, the effects of the APP1 concentration and temperature (278.2-313.2 K) on the solubility of MAP, solution density, and pH value in the ternary equilibrium system (APP1-MAP-water) were measured. The simplified Apelblat model, two empirical polynomials, and rational two-dimensional functions can describe the experimental solubility data, solution density, and pH value well, respectively, with reliable modeling parameters (R 2 > 0.99). In the OptiMax1001 reactor, the focused beam reflectance measurement (FBRM), the particle-view measurement (PVM), and the ReactIR 15 probes were used to observe and reverse verify that they can be synergistically codissolved to achieve economic efficiency. Basic thermodynamic data and models can guide their collaborative application in irrigation to improve the phosphorus utilization rate.

Fulvic-polyphosphate composite embedded in ZnO nanorods (FA-APP@ZnO) for efficient P/Zn nutrition for peas (Pisum sativum L.).

A nano-fertilizer (FA-APP@ZnO) was designed and prepared based on the copolymer of fulvic acid (FA) and ammonium polyphosphate (APP) with ZnO nanorods embedded, to tackle the antagonism between phosphorus (P) and zinc (Zn) in fertilization. FA-APP@ZnO was confirmed to revert the precipitability of H2PO4 - and Zn2+ into a synergistic performance, where FA and APP can disperse ZnO nanorods, and in return, ZnO catalyzes the hydrolysis of the absorbed APP. The hydrolysis rate constant of pyrophosphates consequently increased 8 times. The dry biomass of pea (Pisum sativum L.) under the FA-APP@ZnO hydroponics for 7 days increased by 119%, as compared with the situation employing the conventional NH4H2PO4 and ZnSO4 compound fertilizer. Moreover, the uptake of seedlings for P and Zn was enhanced by 54% and 400%, respectively. The accelerated orthophosphate release due to ZnO catalysis and the well-dispersed ZnO nanorods enabled by APP met the urgent demand for P and Zn nutrients for peas, especially at their vigorous seedling stage. This work would provide a new idea for constructing nano-platforms to coordinate the incompatible P and Zn nutrients for the improvement of agronomic efficiency.