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The mobility of nitrogen (N) in the environment is conditioned by its cycling between atmospheric, terrestrial, and marine ecosystems. It is a key element for global biogeochemistry, and although isotope analysis has been an integral part of many studies over the past eighty years, the complexity of the nitrogen cycle hinders a correct and detailed understanding of the mechanisms behind its processes. It could be argued that the interpretation of the isotopic signatures of nitrogen in soils is still in its infancy. In Croatia, such research has recently begun and is driven by a need for the comprehensive study of nitrogen isotopes in terrestrial ecosystems. The aim of this study was to compare the abundance of the 15N isotope in soils from continental and coastal parts of Croatia with different types of land use (arable land/crop production, meadows, forests, orchards, ski slopes, urban soil/city roads) and to authenticate the nitrogen origin in soils in relation to different soil management practices. This research was based on 27 soil samples collected at 11 locations in Croatia. The samples differed according to soil type, land use, applied mineral and organic nitrogen fertilization, and climatic condition at each specific location. The determination of δ15NT (T—total nitrogen) values in bulk samples was performed in duplicate with the IRMS (Isotope Ratio Mass Spectrometry) method using an IsoPrime100-Vario PYRO Cube (OH/CHN Pyrolyser/Elemental Analyzer). The results reveal that the mean δ15N abundance in soils according to different land use declines in the following order: crop production (+5.66 ± 1.06‰) > apple orchard (+5.60 ± 0.10‰) > city road (+4.33 ± 0.38‰) > meadow (+3.71 ± 0.85‰) > ski slope (+2.20 ± 0.10‰) > forest (+2.15 ± 1.86‰). The individual values were in the range from 0.00 ± 0.10‰ in the forest soil in continental Croatia to +7.19 ± 0.07‰ in the vegetable garden (crop production) soil in coastal Croatia. Among the investigated soil properties and weather conditions, PCA analysis identified close correlations between P2O5 content and δ115N abundance in arable soils, as well as between soil reaction (pH) and mean annual temperatures, while high C/N ratio values explained the isotopic distribution in non-arable soils (city roads and forests). Despite the long-term application of mineral nitrogen fertilizers, the results represent nitrogen of organic origin in the arable soils (crop production), which partly confirms the sustainable management of those agroecosystems. [ABSTRACT FROM AUTHOR]

According to the Scopus database, over the last five years, 91 scientific papers with the keyword "pXRF" (portable X-ray fluorescence) were published in indexed journals in the domain of environmental science and agricultural science, which indicates more frequent applications of this technique in scientific research. The pXRF method is characterized by speed, precision, accuracy, and the possibility of a simultaneous analysis of a large number of elements, albeit with higher limits of detection (LODs) as a major disadvantage. The presence of metals in certain phosphate fertilizers is well established, though not to the same extent as in mineral nitrogen fertilizers. The aim of this research was to determine the metal content (As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Si, Sr, Th, U, Zn, Zr, and Y) in thirteen commercial mineral nitrogen fertilizers via the pXRF method. Six straight fertilizers (ammonium nitrate, ammonium sulphate nitrate, limestone ammonium, nitrate, and urea) and seven complex fertilizers (various NPK formulations), which are different even according to their production technology, produced in Croatia were analyzed using the handheld Vanta C (Olympus) XRF analyzer according to the loose powder method and "point and shoot" technique. Data quality control was performed by analyzing the reference fertilizer samples and certified and reference soil samples. The results revealed that the determined contents of Cd, Mn, and Th were relatively higher in the single-component fertilizers, while the contents of As, Cr, Fe, Ni, Si, Sr, Zn, Zr, Y, and U were relatively higher in the complex fertilizers. Due to the higher LODs of Co and Pb (3 mg/kg) and Mo (2 mg/kg), the pXRF method was not appropriate for the determination of these metals in the analyzed fertilizers. The quantified metal content in the analyzed fertilizers varied as follows: 2.0–8.0 mg As/kg; 11.5–31.3 mg Cd/kg; 29.8–118.5 mg Cr/kg; 7.8–26.3 mg Cu/kg; 16.5–2209 mg Fe/kg; 20.3–5290 mg Mn/kg; 6.2–27.8 mg Ni/kg; 1156–4581 mg Si/kg; 2.0–469.8 mg Sr/kg; 3.0–35.3 mg Th/kg; 2.0–82.8 mg U/kg; 1.4–166 mg Zn/kg; 9.7–15.3 mg Zr/kg; and 16.5–128.0 mg Y/kg. The results indicated that the pXRF method is particularly suitable for measurement and metal detection in complex nitrogen mineral fertilizers with higher amounts of metals, but it is not suitable for the detection and quantification of the lower amounts of As, Zr, Y, Cu, Ni, and Cr in single-component nitrogen fertilizers. Compared to all of the investigated fertilizers, the highest amounts of As, Cr, Cu, Fe, Ni, U, Zn, and Zr were quantified in the NPK 7-20-30 formulation. [ABSTRACT FROM AUTHOR]

Selecting cultivars with greater biomass results in higher yields and greater carbon sequestration. Storage of atmospheric carbon in the plant/soil pool contributes not only to food security but also to mitigating climate change and other agroecological benefits. The objective of this study was to determine: (1) grain, residue, and root biomass yields; (2) harvest indexes; (3) residue-to-product ratio; (4) root-to-shoot ratio; (5) biomass carbon and nitrogen contents; and (6) C:N ratios for two new and two old winter wheat cultivars. The greatest yield difference was found between old Srpanjka (the lowest) and new Kraljica (the highest) cultivar where grain, residue, root, and total biomass yield was higher by 38%, 91%, 71%, and 64%, respectively. Total biomass was composed of 40–47% grain, 10–11% roots, 32–36% stems + leaves, 9–11% chaff, and 1–2% spindle. The range of HI was 0.45–0.53, RPR 0.91–1.25, and R:S ratio 0.12–0.13. For all cultivars, positive carbon and negative nitrogen balance within the plant pool was determined. Still, root biomass and rhizodeposition carbon remain open questions for a better understanding of agroecosystems' C dynamics. [ABSTRACT FROM AUTHOR]

Given that global amounts of waste are growing rapidly, it is extremely important to determine what amount of waste will be generated in the near future. Accurate waste forecasting is also important for planning and designing a sustainable municipal solid waste (MSW) management system. For that reason, there is a need to build a model to predict the amount of MSW generated in the near future. Based on previous research, artificial neural networks (ANN) show better results in predicting waste generation compared to other mathematical models. In this research, an ANN model using the iterative algorithm Broyden–Fletcher–Goldfarb–Shanno (BFGS) for the prediction of MSW fractions, based on the socio-demographic characteristics, economic and industrial data obtained in Croatia and summarized data of the member states of EU (EU-27 from 2020), showed good predictive capabilities. The coefficient of determination during the training cycle for the output variables; household and similar waste (HHS), paper and cardboard waste (PCW), wood waste (WW), textile waste (TW), plastic waste (PW) and glass waste (GW) were 0.993; 0.997; 0.999; 0.997; 0.998; and 0.998, respectively, while reduced chi-square, mean bias error, root mean square error, mean percentage error, average absolute relative deviation and sum of squared errors were found low. In this paper, Yoon′s method of interpretation shows the relationships between socio-demographic data and the amount of generated waste. The results indicate that the lowest level of education shows a negative impact on observed waste-types calculations, with a relative impact between −9.889 and −4.467%. The most pronounced positive impact on the calculation of HHS, PCW, WW, TW, PW and GW was observed for year variable, gross domestic product, exports of goods and services, imports of goods and services, wages and salaries, secondary income, arrivals in collective accommodation establishments, overnight stays in collective accommodation establishments and exports of petroleum and petroleum products to partner countries, with a relative influence of 4.063–7.028; 2828–4851; 5240–6197; 5.308–6.341; 4290–4810; 4533–5805; and 4.345–4.493, respectively. The obtained results indicate that the amount of HHS waste at the EU-27 level in 2025 will decrease by approximately 18% compared to the data from 2018. The quantities of other observed recyclable types of waste will increase by 34% for PCW, 310% for WW, 40% for TW, 276% for PW and about 67% for GW. The amount of waste generated provides the basic information needed to plan, operate and optimize the waste management system. It could also help in the transition to an environmentally friendly and economically profitable circular economy. The model created in this research could also help with the system of separate waste collection, which would lead to more efficient recycling and the achievement of the set goals for recycling 55% of municipal waste by 2025. [ABSTRACT FROM AUTHOR]

Biological carbon sequestration is considered an important strategy to mitigate climate change. The energy crop Miscanthus × giganteus has great sequestration potential. The objective of this study was to determine: a) the dry matter yield and carbon content in aboveground and belowground biomass; b) the total carbon balance in the plant and soil pool. The study was conducted in continental Croatia (N 45°51′01.32″; E 16°10′35.85″) by the destructive harvesting of five-year-old Miscanthus × giganteus stands established by rhizomes (MxgR) and seedlings (MxgS) in the spring of 2021. The soil sampling was conducted in 2016 and 2022. The average amount of carbon in the aboveground biomass of MxgR and MxgS is 11.51 t/ha and 9.87 t/ha, respectively, and in the belowground biomass it is 13.18 t/ha and 14.90 t/ha, respectively. The carbon balance in the plant pool of MxgR is three times lower (1.67 t/ha) than that in the plant pool of MxgS (5.03 t/ha). The total soil carbon content increased by 8.7 t/ha under MxgR and by 14.8 t/ha under MxgS during 2016–2022. Therefore, under the studied agroecological conditions, seedlings should be preferred over rhizomes in the selection of planting material. The obtained data represent valuable input data for sequestration modeling. [ABSTRACT FROM AUTHOR]

The production of energy crops' biomass requires appropriate policies to secure long-term support to improve crop productivity and to ensure the environmental, economic, and social benefits of the cropping systems [[2]]. This editorial belongs to the Special Issue "Impact of Nutrients and Trace Elements in Soil on Plant Growth: Case of the Second-Generation Energy Crops". 2015; Volume 72. 978-2-9545557-0-6 3 Pidlisnyuk V.V., Erickson L., Stefanovska T., Popelka J., Hettiarachchi G., Davis L., Trögl J. Potential Phytomanagement of Military Polluted Sites and Biomass Production Using Biofuel Crop Miscanthus × giganteus. [Extracted from the article]

Nonsustainable agricultural practices often lead to soil carbon loss and increased soil carbon dioxide (CO2) emissions into the atmosphere. A research study was conducted on arable fields in central lowland Croatia to measure soil respiration, its seasonal variability, and its response to agricultural practices. Soil C-CO2 emissions were measured with the in situ static chamber method during corn (Zea mays L.) and winter wheat (Triticum aestivum L.) growing seasons (2012 and 2013, n = 288) in a field experiment with six different tillage treatments. During corn and winter wheat growing season, average monthly soil C-CO2 emissions ranged, respectively, from 6.2-33.6 and 22.1-36.2 kg ha-1 day-1, and were decreasing, respectively, from summer > spring > autumn and summer > autumn > spring. The same tillage treatments except for black fallow differed significantly between studied years (crops) regarding soil CO2 emissions. Significant differences in soil C-CO2 emissions between different tillage treatments with crop presence were recorded during corn but not during winter wheat growing season. In these studied agroecological conditions, optimal tillage treatment regarding emitted C-CO2 is plowing to 25 cm along the slope, but it should be noted that CO2 emissions involve a complex interaction of several factors; thus, focusing on one factor, i.e., tillage, may result in a lack of consistency across studies. [ABSTRACT FROM AUTHOR]

Pipeline spills and pollution of the environment by crude oil pose a threat to natural resources, especially soil and water. One such incident occurred on 25 September 2018 in the area of Budrovac (Croatia; 46°00′14.6″ N 17°04′16.8″ E) on agricultural land as a pipeline spill. Bioremediation of the contaminated soil was carried out with organic pollutants using an environmentally safe absorbent Spill-Sorb (Canadian Sphagnum Peat Moss) and a mineral fertilizer—nitrogen. The experiment was conducted in the greenhouse of the Faculty of Agriculture, Croatia, during a six-month (October 2018–April 2019) study. Samples of agricultural soils contaminated with total petroleum hydrocarbons (TPHs) and polycyclic aromatic hydrocarbons (PAHs) were taken after the rupture of the local gas condensate pipeline. The experiment was conducted in five treatments in triplicate: I-control (clean soil); II-100% contaminated soil + organic absorbent + nitrogen; III-100% contaminated soil + organic absorbent; IV-50% clean soil + 50% contaminated soil + organic absorbent + nitrogen; and V-50% clean soil + 50% contaminated soil + organic absorbent. The soil properties studied were pH, organic matter content, carbon and nitrogen content and ratio, and changes in the concentration of potential organic contaminants—TPHs and individual PAHs. The results demonstrated that the mixture of organic absorbent and nitrogen efficiently removed organic pollutants from the contaminated soil within six months. However, the application of Spill-Sorb alone was more effective for the degradation of hydrocarbons. The effectiveness of the absorbent studied was dependent on the concentration of organic pollutants and nitrogen application. [ABSTRACT FROM AUTHOR]

The research objective was to use proximal spectroscopy in visible and near infrared (VNIR) spectra to determine the total leaf nitrogen (TN) content and the above-ground biomass of Miscanthus × giganteus (MxG) grown in the open-roof greenhouse experiment on soil contaminated with cadmium and mercury (100 mg Cd/kg soil; 20 mg Hg/kg soil), in dependence of different soil amendments in four treatments (I-soil without amendment; II-sludge; III-mycorrhizae; IV-MxG ash). Leaf reflectance was acquired using a field spectroradiometer (350–1050 nm) at the end of the vegetation period between 2018 and 2019 (n = 24). TN content was determined using the dry combustion method, while biomass was weighted immediately after the harvest. In terms of the treatment effect, sludge showed the greatest contribution in TN content. Regarding the biomass quantity, MxG ash revealed the best results as soil amendment. Applying the partial least squares regression, complete correlation and low root mean squared error (RMSE) were obtained between predicted and measured values for the validation dataset of TN content (R2 = 0.87, RMSE = 0.139%), while a strong correlation was calculated for biomass (R2 = 0.53, RMSE = 0.833 t/ha). As an additional tool with analytical methods, proximal spectroscopy is suitable to integrate the optical and physiological properties of MxG, and to assess nutrient stress in crop grown on contaminated soils. [ABSTRACT FROM AUTHOR]

Agricultural greenhouse gas emissions can be reduced by the cultivation of cultivars with lower carbon footprint. Considering the hypothesis that there are differences in soil respiration, due to differences in physiological and morphological characteristics of wheat and barley, the aim of this study is an assessment of soil respiration rates and microclimate under different cover (bare soil, wheat, and barley) and cultivar (four barley and four wheat) types. Soil respiration was determined by in situ closed static-chamber method in continental Croatia, during the 2020/2021 season. The seasonal pattern of the soil respiration was similar for all cultivars, respiration was increasing with crop development stages until maturity, when it decreased until the harvest. Cover type did not have influence on soil microclimate but did have on soil respiration. Bare soil had significantly lower annual respiration rates, compared to the barley/wheat covers. Average annual respiration rates were similar between the barley and wheat covers, as well as between all studied barley cultivars. A significant difference between winter wheat cultivars have only been determined between the Renata (9.78 kg C-CO2 ha−1 day−1) and El Nino (12.67 kg C-CO2 ha−1 day−1) cultivars. However, the determination of the total carbon budget is needed, in order to determine the most suitable cultivar, in the light of climate change. [ABSTRACT FROM AUTHOR]