CALIBRATION OF BONDING MODEL PARAMETERS FOR COATED FERTILIZERS BASED ON PSO-BP NEURAL NETWORK

In this paper, the ultimate crushing displacement and ultimate crushing load of the coated fertilizer granules were obtained by uniaxial compression test as 0.450 mm and 58.668 N, respectively. Then the DEM model of the encapsulated fertilizer was established, and the Plackett-Burman and Steepest ascent tests were taken to determine the factors that had significant effects on the results and their ranges of values, respectively. Finally, the PSO_BP neural network was trained using full-factor test data, and the correlation coefficients of training process, validation process, testing process and overall performance were obtained as 0.98057, 0.95781, 0.96724 and 0.97459, respectively, indicating that the trained PSO_BP neural network fits well and can predict the ultimate crushing displacement and ultimate crushing load. The ultimate crushing displacement Y1 and ultimate crushing load Y2 are 0.450 mm and 58.703 N, with a minimum relative error of 0.06% from the actual value. This study can provide new methods and ideas for the calibration of discrete element simulation parameters.

Bio-based polyurethane nanocomposite thin coatings from two comparable POSS with eight same vertex groups for controlled release urea

Nanocomposite modification has attracted much attention in improving properties of bio-based polymer coating material for coated fertilizer. Herein two comparable polyhedral oligomeric silsesquioxanes (POSS), with eight poly(ethylene glycol) (PEG) and octaphenyl groups attached to the cage, respectively, were successfully incorporated into thin castor oil-based polyurethane coatings via in-situ polymerization on the urea surface. The nanostructure coatings are environmentally friendly, easy to prepare, and property-tunable. The results show that the vertex group of POSS had a pronounced influence on dispersion level and interaction between polyurethane and POSS that well-tuned the release pattern and period of coated urea, even at the coating rate as low as of 2 wt%. The liquid POSS with long and flexible PEG groups had better compatibility and dispersibility in polyurethane matrix than the solid POSS with rigid octaphenyl groups, as evidenced by SEM/EDS. The unique properties were resulted from the different extents of physical crosslinkings. This modification of bio-based polyurethane coating with POSS provided an alternative method of regulating and controlling the properties of coated fertilizer.

Permeability of N, P, K-fertilizer nutrient and water vapor through PLA, PLA/PS, and PLA/HA membranes

To collect permeability data and establish its database of fertilizer nutrients and water vapor through different polymer membranes for the development of polymer-coated fertilizer, the permeabilities of N-, P-, and K-nutrient from saturated aqueous of urea, NaH2PO4 and KCl solution and the permeability of water vapor through the membranes of poly lactic acid (PLA), its blends with polystyrene (PS), and its composites with humic acid (HA) particles were determined experimentally at the temperatures of 288, 298, and 308 K, respectively. The effects of the addition of PS and HA particles, temperature, and coating thickness on the permeability of fertilizer nutrient and water vapor were investigated. It was found that the addition of PS and HA increased the permeability for both the fertilizer nutrients and water vapor. The increase in temperature raised the permeability of N-, P-, and K-nutrient while decrease the permeability of water vapor in the range studied.

The Influence of Biopolymer Coated Fertilizer on the Agrochemical Parameters of the Soil

This papper is about the use of biopolymer of polyvinyl alcohol (PVA) as a coat of different fertilizer granules (Azafoska 16:16:16 and Yara Kristalon 19:19:19) as a core material in presence of nitric acid. The biodegradable polymer layer provides uniform diffusion of minerals into the soil as the PVA shell decays. Scanning Electron Microscope (SEM) and Energy – Dispersive X-ray spectroscopy (EDX - 3600) were carried out for the characterization of bio-modified materials. The agrochemical changes of the soil in terms of macro-and microelements were also determined.

Nitrogen coated fertilizer with controlled release for the maize crop

Maize represents one of the most cultivated crops of cereals in the world, being used as a source of grain, silage and biofuel. Nitrogen is very required in the maize crop, making nitrogen fertilization a significant part of the production cost. The objective of this study was to evaluate the response of two sources of N, urea and coated urea of controlled release, regarding the productivity and the cost/benefit ratio in maize for 2nd harvest. The experiment was carried out in the field in soil classified as dystroferric Red Latosol and treatments distributed in experimental plots, following the randomized block design with four replications. The treatments were 40 kg N ha-1 of common urea; 60 kg N ha-1 of common urea; 40 kg N ha-1 of coated urea; 60 kg of N-coated urea and the control without application of N broadcast application in planting. The maize crop responded to the application of nitrogen at planting. However, the use of coated urea did not increase the grain yield in relation to the use of common urea. The economic analysis demonstrated a better efficiency of use of N and the best net revenues with the application of the dose of 40 kg N ha -1 of common urea in the planting of the crop.