Improving the mechanical properties of tool steel by induction chemical-thermal treatment

The study results of the structure and microhardness of the surface layer of high-speed tool steel after induction chemical-thermal treatment in a gaseous nitrogen-containing medium at a temperature of 900–1100 °C were presented. Due to the strengthening treatment of products a gradient diffusion nitride layer with a thickness of about 200 μm and a surface microhardness of 1950±70 HV1 98 was formed.

Biotechnological approaches to develop nitrogen-fixing cereals: A review

ricultural yields are often limited by nitrogen (N) availability, especially in countries of the developing world, whereas in industrialized nations the application of chemical N fertilizers has reached unsustainable levels that have resulted in severe environmental consequences. Finding alternatives to inorganic fertilizers is critical for sustainable and secure food production. Although gaseous nitrogen (N2) is abundant in the atmosphere, it cannot be assimilated by most living organisms. Only a selected group of microorganisms termed diazotrophs, have evolved the ability to reduce N2 to generate NH3 in a process known as biological nitrogen fixation (BNF) catalysed by nitrogenase, an oxygen-sensitive enzyme complex. This ability presents an opportunity to improve the nutrition of crop plants, through the introduction into cereal crops of either the N fixing bacteria or the nitrogenase enzyme responsible for N fixation. This review explores three potential approaches to obtain N-fixing cereals: (a) engineering the nitrogenase enzyme to function in plant cells; (b) engineering the legume symbiosis into cereals; and (c) engineering cereals with the capability to associate with N-fixing bacteria.

Reactive Nitrogen Releases And Nitrogen Footprint During The Life-Cycles of Intensive Vegetable Production Affected By Human Feces Slurry Substitution

Evaluating the sustainability of vegetable production is crucial to secure future food supply. A two-year field study of four different vegetable crops was performed to investigate the effects of inorganic fertilizer and human feces slurry at different ratios on vegetable yields, reactive gaseous nitrogen emissions (GNrEs), reactive nitrogen (Nr) footprint and net ecosystem-economic income (NEEI) by using life-cycle analysis. Four fertilization strategies were studied, including: CK (no fertilization); CF (inorganic fertilization); CHF1 (human feces slurry/inorganic fertilizer, N ratio=1:7); and CHF2 (human slurry/inorganic fertilizer, N ratio=1:3). Results showed that compared with CF treatment, both CHF1 and CHF2 treatments increased the N2O+NO emissions by 11.8 % and 32.4 % on average, while decreased the vegetable yields by 6.7 % and 7.4 %, respectively. Moreover, the addition of human feces slurry increased the proportions of Nr footprint by 6.6 % (CHF1) and 2.9 % (CHF2) in comparison with CF treatment group. However, although CHF2 treatment significantly increased the values of GNrEs and reactive gaseous nitrogen intensity (GNrI) by 8.4 % and 12.5 %, respectively, in relation to those in CF treatment group, it still increased farmers’ income by 16,404 CNY ha−1. These findings suggest that although human feces slurry incorporation could not mitigate Nr releases, the appropriate ratio of inorganic fertilizer and human feces slurry (CHF2) is able to improve net economic income (NEI) and NEEI during intensive vegetable production. Nevertheless, the relationship between combinatorial treatment of inorganic fertilizer and human feces slurry and mitigation of Nr release should be explored further.

Gaseous nitrogen losses from pig slurry fertilisation: can they be reduced with additives in a wheat crop?

Aim of the study: The use of pig slurry as fertiliser is associated with gaseous nitrogen (N) losses, especially ammonia (NH3) and nitrous oxide (N2O), leading to environmental problems and a reduction of its fertiliser value. This study evaluates, in an irrigated wheat crop, the effect of different additives mixed with pig slurry to decrease NH3 and N2O losses.Area of study: Middle Ebro valley, SpainMaterials and methods: The treatments were: i) non-N-fertilised control, ii) pig slurry (PS), iii) pig slurry with the urease inhibitor monocarbamide dihydrogen sulphate (PS-UI), iv) pig slurry with a microbial activator in development (PS-A), and v) pig slurry with the nitrification inhibitor 3,4-dimethylpyrazole phosphate (PS-NI). Pig slurry was applied at a target rate of 120 kg NH4+-N ha-1. Ammonia volatilisation was measured using semi-opened static chambers after treatments application at presowing 2016 and side-dressing 2017. Nitrous oxide emissions were measured using static closed chambers after treatments application at the 2017 and 2018 side-dressing.Main results: Ammonia volatilisation was estimated to be 7-9% and 19-23% of NH4+-N applied after presowing and side-dressing applications, respectively. Additives were not able to reduce NH3 emissions in any application moment. PS-NI was the only treatment being effective in reducing N2O emissions, 70% respect to those in PS treatment. Crop yield parameters were not affected by the application of the additives because of the no effect of additives controlling NH3 losses and the low contribution of N2O losses to the N balance (<1 kg N2O-N ha-1).Research highlights: The use of 3,4-dimethylpyrazole phosphate would be recommended from an environmental perspective, although without grain yield benefits.