Release of Nitrogen from Granulate Mineral and Organic Fertilizers and Its Effect on Selected Chemical Parameters of Soil

The objective of this work was the evaluation of the release patterns of nitrogen from various types of fertilizers and their impact on selected chemical parameters of calcareous soil. Three mineral fertilizers and two organic fertilizers were tested in the laboratory for 35 days. This study showed the rapid release of nitrogen from mineral types. More than 70% of the nitrogen was released from the ammonium granules and 98% from the urea granules. The rate of nitrogen release from pellets of organic origin was much slower than from mineral pellets, the released N was 15–28% of the original amount. Soil pH was altered by incubation. The content of soil N changed significantly due to the incubation of N mineral fertilizers; no changes were observed for organic fertilizers. The EC value of the soil solution was significantly modified under the influence of mineral granules, it reached a maximum of 1147 µS cm−1 on the 10th day, and for organic fertilizers of 944 µS cm−1 on the 35th day. The results of this study characterize each N release pattern, providing data to support a more efficient nutrient management strategy in calcareous soils and the effect of incubated fertilizers on soil chemical parameters.

Comparative effect of various organic extracts coated urea fertilizer on the release pattern of Ammonium and Nitrate in the soil at different time intervals

Nitrogen (N) fertilizer application is a very important commodity in agricultural systems. However, due to the losses of applied N from the soil microenvironment its efficiency is too low. Different strategies like the use of polymer coating and use of chemical nitrification inhibitors had been employed to reduce N losses. But these chemical nitrification inhibitors are very expensive. Thus, a study was conducted to investigate the effects of different concentrations of parthenium extract, neem oil and acidulated cow dung compost extract on N dynamics in the soil. Three concentrations of parthenium extract (5, 10 and 15 %) and neem oil (1, 2 and 3 %) were coated on urea granules after mixing with the polymer material. Three pH (2, 4 & 6 pH) based acidulated cow dung compost extracts were also coated on urea granules in the same pattern. These coated fertilizers and uncoated urea were applied in jars filled with soil (100g per jar) at the rate of 1g of fertilizer per jar. One treatment was kept as control (without any fertilizer). Treatments along three replications were arranged according to the completely randomized design (CRD). Results depicted that all coating materials caused the release of N consistently from applied fertilizers compared to uncoated treatment. In addition, percent nitrified N was also reduced significantly in coated treatments in comparison to the uncoated urea and control treatments. However, the level of concentration effect was not obvious as lower concentrations of these extracts and oil also performed almost equal to that of higher concentrations.

Performance of Urea-Based Fertilizers Associated With Elemental Sulfur or Polymers on Ammonia Volatilization

High N-NH3 losses are expected when conventional urea is applied to the soil surface. In order to reduce it, urea granules could be coated with different materials to decrease fertilizer dissolution rate or to stabilize N-NH4+ by acidification. In this study, we investigated the effect of a polymer-coated urea and powdered S0 added to urea, in the presence or absence of a S-oxidizing bacterium (Acidithiobacillus thiooxidans), on soil pH, SO42- availability, NH4+, and NH3 volatilization. Applying S0 before urea and the inoculation with bacteria have promoted the highest S0 oxidation rates. The greater decrease in soil pH occurred when S0 was applied before urea at a higher dose, which also decreased NH3 volatilization by 83% up to 4 days after urea application. However, the decrease in soil pH did not increase the concentration of NH4+, nor did it decrease the accumulated amount of volatilized NH3 over time. The inoculation of A. thiooxidans accelerates S0 oxidation process, but it was insufficient to counteract the H+ consumption by urea hydrolysis. Therefore, the S0 application with urea did not offer chemical protection against NH3 loss, but a physical barrier in the controlled-release urea had less dissolved urea in soil and reduced NH3 losses.

Controlling nitrogen pollution via encapsulation of urea fertilizer in cross-linked corn starch

High fertilizer inputs augment the reactive nitrogen level in soil, air, and water. Unused reactive nitrogen acts as a pollutant and harms natural resources. This study focused on the thermal processing of corn starch into a coating material using disodium tetraborate and urea. The processed corn starch was coated over granular urea in a vertical bed coating reactor. The chemically modified starch, when compared with native starch, exhibited better stability and mechanical strength over time. The modified starch looked like a weak gel, and its loss modulus was dominated by the storage modulus. However, for native starch, the viscous component dominated the elastic component, especially at lower angular frequencies. The nitrogen release from the coated urea was remarkably slower than the uncoated one. A small difference in the peak and final starch viscosities in the presence of urea and borate revealed low thermal cracking of the starch molecules. The surface of the granular urea that was coated with chemically modified corn starch was uniform, dense, hard, and least porous. The uncoated urea granules became released into water in 6 min under gentle shaking, whereas the coated urea took almost 32 min to completely release.

DESIGN OF AN EXPERIMENTAL DEVICE FOR THE MEASUREMENT OF THE COEFFICIENT OF RESTITUTION

In this work an experimental device was designed and built to measure the coefficient of restitution of particles of different type and size. The aim of the study is to analyze the dependence of the coefficient of restitution with the impact velocity, the shape and mass of the particles. Three types of particles of different origin and shape were used: lentils, urea granules and polyethylene pellets. Besides, two impact materials were evaluated: steel and polycarbonate. The images were captured with a high resolution camera, recording the moment at which the particles impact and bounce on the surface. Image processing software was used to obtain the position of the particle at the instants before and after the impact. The particle velocities before and after the collision were calculated and the coefficient of restitution of the particles were obtained. The experimental results showed the dependence of the coefficient of restitution with the studied variables, providing useful information about the energy dissipation for numerical simulations and a breakthrough in the study of gas-solid flow systems.

Development of a Polyacrylate/Silica Nanoparticle Hybrid Emulsion for Delaying Nutrient Release in Coated Controlled-Release Urea

Polyacrylate/silica hybrid emulsions were prepared by blending aqueous silica nanoparticles with polyacrylate emulsion, which were used for coating urea granules. After incorporating 1.0 wt.% silica nanoparticles into polyacrylate emulsion, preliminary solubility of CRU was decreased from 38.3% to 2.2%, and the release duration was extended from 8 to 27 days. The hybrid coating remarkably delayed the release of urea via improving wear-resistance due to the enhanced hardness, reducing water vapor permeability because of the tortuous diffusion pathway, and less breakage of CRU granules resulted from higher glass transition temperature. Meanwhile, the processibility was improved, which prevented particle agglomeration during coating. Therefore, aqueous silica nanoparticles have potential application in polymer emulsion coated controlled-release fertilizers.