The effect of nitrogen-sulphur fertilizer with nitrification inhibitor on winter wheat (Triticum aestivum L.) nutrition

The high input of nitrogen is often required in today's agriculture, especially for the most cultivated crops largely involved in human and animal nutrition, such as winter wheat. Nitrogen is a mobile nutrient in the soil, and the high doses of N are often associated with possible losses through volatilization or leaching. One of the possible options to increase nitrogen use efficiency is the application of fertilizers with inhibitors. The main objective of the presented three-year experiment established under the field conditions at the two experimental sites was to examine the effect of nitrogen-sulphur fertilizer (ammonium nitrate sulphate) with the inhibitors of nitrification (IN) (dicyandiamide and 1,2,4 triazole). In addition to the nitrogen content in two forms, this fertilizer also contains sulphur, which can possibly enhance the utilization of nitrogen due to their well-known synergy. The treatments included in the experiment were: 1. Unfertilized, 2. N technology 3. N + S technology and 4. N + S + IN. The total dose of applied N for every fertilized treatment was 159 kg/ha. Treatments 2 and 3 were fertilized with three split doses of N, treatment 4 was fertilized only two times due to the addition of IN (a higher dose of fertilizer in the second application). The results obtained from the three-year experiment showed a significantly higher yield of grain (8.18 t/ha) after the fertilization with N + S + IN in comparison with N + S (7.67 t/ha) and N (7.61 t/ha), which proved the positive effect of IN on nitrogen use efficiency during the vegetation. The differences between qualitative parameters of wheat grain (hectolitre weight, protein and gluten content) were evaluated as statistically insignificant for each fertilized treatment. This similar result is likely due to the IN application, which provided a continuous nitrogen supply during vegetation comparable to the three split nitrogen applications. Thus, our results showed, that the addition of IN to the higher dose of fertilizer applied earlier in the vegetation can provide comparable results in terms of quality to the technologies based on three split fertilizations. The three-year experiment established at two experimental sites has proved, that the application of ammonium sulphate nitrate fertilizers with IN in a higher dose is a better option to the commonly used nitrogen technology, which was also supported by the economic evaluation and the highest net profit.

Quantitative Evaluation of Noncovalent Interactions between 3,4-Dimethyl-1H-pyrazole and Dissolved Humic Substances by NMR Spectroscopy

Nitrification inhibitors (NI) represent a valid chemical strategy to retard nitrogen oxidation in soil and limit nitrate leaching or nitrogen oxide emission. We hypothesized that humic substances can complex NI, thus affecting their activity, mobility, and persistence in soil. Therefore, we focused on 3,4-dimethylpyrazole phosphate (DMPP) by placing it in contact with increasing concentrations of model fulvic (FA) and humic (HA) acids. The complex formation was assessed through advanced and composite NMR techniques (chemical shift drift, line-broadening effect, relaxation times, saturation transfer difference (STD), and diffusion ordered spectroscopy (DOSY)). Our results showed that both humic substances interacted with DMPP, with HA exhibiting a significantly greater affinity than FA. STD emphasized the pivotal role of the aromatic signal, for HA-DMPP association, and both alkyl methyl groups, for FA-DMPP association. The fractions of complexed DMPP were determined on the basis of self-diffusion coefficients, which were then exploited to calculate both the humo-complex affinity constants and the free Gibbs energy (K_d and ΔG for HA were 0.5169 M and -1636 kJ mol^-1, respectively). We concluded that DMPP-based NI efficiency may be altered by soil organic matter, characterized by a pronounced hydrophobic nature. This is relevant to improve nitrogen management and lower its environmental impact.

Electrochemical Synthesis of Nitric Acid from Nitrogen Oxidation

Nitric acid has been widely applied in agriculture and industries. The present manufacturing process via a combination of the Haber-Bosch process and the Ostwald oxidation process is accompanied by massive energy consumption and greenhouse gas emissions. A direct electrocatalytic nitrogen oxidation reaction (NOR) to nitric acid is a promising alternative, especially when it is driven by renewable energy sources. The standardization of performance evaluation is the premise for the design and synthesis of efficient electrocatalysts for NOR. In this regard, this review first discusses the history of the development of HNO 3 manufacturing and the possible reaction mechanisms for electrocatalytic NOR. Then, a strict protocol for electrochemical NOR experiments is recommended. Finally, general research targets associated with techno-economic analysis, challenges, and prospects for NOR are summarized for future studies.

Synthesis of a Novel Polymer Nitrification Inhibitor with Acrylic Acid and 3,4-Dimethylpyrazole

Nitrification inhibitors (NIs) are widely applied in soil to improve the nitrogen utilization efficiency. Currently, commonly used nitrification inhibitors, like 3,4-dimethylpyrazole phosphate (DMPP), are not resistant to high temperature and do not have a phosphate-solubilizing ability. In this paper, a novel polymer nitrification inhibitor (PNI) with nitrification inhibition ability, phosphate-solubilizing ability, and good thermal stability is chemically synthesized from acrylic acid (AA) and 3,4-dimethylpyrazole (DMPZ). The PNI has a high glass transition temperature (T_g: ∼78 °C) and effective decomposition temperature (T_d: ∼216 °C). The good thermal stability makes it suitable for high tower granulation processes. The PNI demonstrates an excellent nitrification inhibition performance when the dosage is 0.5 wt % of the urea fertilizer and presents good phosphate-solubilizing ability when the volume ratio of PNI to water is about 1:1000. The PNI can be applied to the field to realize nitrogen immobilization and phosphate-solubilizing at the same time or be used as the synergistic additives for fertilizers such as water-soluble fertilizers, liquid fertilizers, and compound fertilizers.

Occurrence and fate of nitrification and urease inhibitors in the aquatic environment

Nitrification and urease inhibitors (NUIs) decelerate the bacterial oxidation of nitrogen species by suppressing the activity of soil microorganisms. Thus, nitrogen losses can be limited and the efficiency of nitrogen fertilizers can be increased. After application NUI transfers to surface water may occur through leaching or surface run-off. In order to assess the occurrence of nitrification and urease inhibitors in the aquatic environment a multi-analyte high-performance liquid chromatography-mass spectrometry method was developed. 1H-1,2,4-Triazole and dicyandiamide (DCD) were detected for the first time in German surface waters. Only at a few sites 1H-1,2,4-triazole has been episodically detected with concentrations up to the μg L(-1)-range. DCD was ubiquitously present in German surface waters. An industrial site was identified as the point source of DCD being responsible for exceptionally high DCD concentrations of up to 7.2 mg L(-1) in close proximity to the point of discharge. Both compounds were also detected in at least one wastewater treatment plant effluent, but their concentrations in surface waters did not correlate with those of typical markers for domestic wastewater. Other NUIs were not detected in any of the samples. Laboratory-scale batch tests proved that 1H-1,2,4-triazole and DCD are not readily biodegradable, are not prone to hydrolysis and do not tend to adsorb onto soil particles. Ozonation and activated carbon filtration proved to be ineffective for their removal.