Oil contamination in soil from a variety of sources, including accidental leaks, industrial activities, and improper waste disposal, involves disrupting ecosystems, contaminating water, harming human health, and diminishing agricultural productivity. Bioremediation is becoming the most important method accepted as a treatment for hydrocarbon-polluted soil using indigenous microbial flora, which aims to restore soils to their pre-hydrocarbon pollution characteristics. We will follow in our article to give some examples of good practices for bioremediation of oil-polluted soils in some sites in NE Romania. In a first step, all the oil extraction wells in NW Romania were mapped, both those in operation and those abandoned, reaching 695 wells. For 7 case studies, soil profiles were taken from the vicinity of the well column and from points close to it located in the well casing, for which the concentration of total petroleum hydrocarbons was determined. Using GIS spatial interpolation techniques, the theoretical concentration of petroleum hydrocarbons in the soil was determined. The polluted soil was transported to the bioremediation station, where it was exposed to bioremediation procedures, and the period and duration until the soil was brought to the accepted parameters in terms of allowable concentrations were analysed. The time required varies between 17 and 36 weeks needed for bioremediation. Following practical applications, it can be concluded that the time required for bioremediation is directly dependent on the initial concentration of pollutants and the number of chemical and physical interventions applied to the soil.

The adaptation measures of agricultural crops to current climate change are also reflected at the level of land-use planning for species with resistance to rainfall shortages and periods of prolonged droughts. The present paper aimed at the spatial modeling of land favorability for alfalfa (Medicago sativa L.) within Bihor county, which is located in Northwest Romania. This was performed by using GIS spatial analysis techniques, particularly the technique of rating agricultural plots by using as a modeling basis the synthetic climate indicators, soil indices, as well as topographic characteristics, which are considered relevant for the studied species. As a result of the modeling process, agricultural plots that are favorable for the alfalfa culture were identified. A comparative analysis of the profit was also carried out both for the green and dry masses of eight types of alfalfa, which are suitable for the national environmental conditions. Land favorability modeling for alfalfa cultivation will be carried out by using GIS spatial analysis techniques, which allow the use of large databases while maintaining the necessary degree of detail, and they make possible the correlations between factors and production estimated per hectare, which are correlations that are characteristic for the environmental factors. Thus, for the studied territory, the best green alfalfa production was identified as being obtained from the Carinca and Daniela varieties, whereas the Mihaela and Teodora varieties were noticed to provide the best dry alfalfa production.

Compared to fossil fuels, biodiesel is a clean fuel, does not pollute the environment, and can be produced from inexhaustible natural sources. The objectives of our research are to study how increasing doses of complex fertilizers, applied to rapeseed oil culture, affect the production of rapeseeds and oil; the comparative study between the quality parameters of refined rapeseed oil (RRO) and fatty acids (FA); and the analysis of the quality of the biodiesel obtained from them (BRO and BFA). The experimental field is set-up in a Latin rectangle format and is placed on a total area of 400 m² divided into 16 parcels, randomized for uniformity with four replications and four fertilizer graduations (N₀P₀K₀—Control, N₁₆₀P₁₆₀K₁₆₀, N₃₂₀P₃₂₀K₃₂₀, N₄₈₀P₄₈₀K₄₈₀). To obtain biodiesel form oil (BRO) and fatty acids (BFA), the processes of esterification, transesterification, refining, washing, sedimentation, and drying were applied. A comparison between biodiesel quality parameters from RRO and FAs were made, and we highlighted the differences in quality compared to samples from the experimental field. The use of large amounts of complex fertilizers leads to high yields of rapeseed (13.3–47.0 q ha⁻¹) and oil (629.8–2130.8 L ha⁻¹), which are statistically significant only for high doses (N₃₂₀P₃₂₀K₃₂₀ and N₄₈₀P₄₈₀K₄₈₀). For most of the qualitative parameters studied, the differences in values between BFA and BRO have positive values, which means a higher quality for BRO. Both BRO and BFA generally fall within the quality parameters imposed by European standards (ES). Although the quality of BRO is superior to BFA, it is produced on a smaller scale due to the nutritional importance of refined rapeseed oil. This study is of particular importance in the optimization of rapeseed fertilization, with a view to the efficient conversion of crude oil, a feedstock for chemical fertilizers and an environmentally friendly fuel.

This paper presents a study of the microbial abundance in post-bauxite-mining land soil from Zece Hotare, Bihor county, Romania. The soil samples were collected from 12 soil variants, in the year 2020, after 15 years of long-term restoration. Some chemical parameters and bacterial numbers of six groups of microorganisms were determined in the restored mining land, and these characteristics were compared with those of the soil from a beech forest situated in an adjacent area unaffected by bauxite exploitation. On the basis of the total number of microorganisms belonging to each group studied, the bacterial potential of the soil quality was assessed, calculating the bacterial soil quality index (BSQI), while the Shannon diversity index and the Jaccard distance were applied to show the level of bacterial diversity. The characteristics of the studied chemical and microbiological parameters determined in the beech adjacent area were very similar to those observed in the high-level plateau, low-level plateau, and Black locust areas, indicating similar soil conditions; therefore, the ecological reconstruction 15 years ago, had a very favorable impact on restoration in some affected areas.

Soil enzyme activities play key roles in the biochemical functioning of soils, nutrient cycling, and in the degradation of litter and artificial substances. Knowledge of soil enzyme activities can provide information on changes in soil quality due to land use management. In this study, we report the actual and potential dehydrogenase and catalase activities involved in intracellular metabolism and phosphatases (phosphomonoesterases) activities involved in phosphorus metabolism under different croplands. Soil was sampled from the 0-10-, 10-20- and 20-30-cm depths from typical clay soil at Livada (Satu Mare County), and from typical chernozem and histosol at Berveni (Satu Mare County). Significant and unsignificant differences were registered in the soil enzymatic activities depending on the kind of enzymatic activity and the type of soil. All enzymatic activities studied were greater in typical chernozem compared to the typical clay soil and histosol. Based on the absolute values of the enzymatic activities, the enzymatic indicator of soil quality (EISQ) was calculated. The EISQ values ranged between 0.605 and 0.989 indicating an appreciable intensity of the enzymatic activities. These values mean that by determination of soil enzyme activities valuable information can be obtained regarding fertility status of soils. The enzyme activities were significantly intercorrelated with r values from 0.814 to 0.989 (p<0.05). A perfect positive correlation between enzymatic indicator of soil quality and grain yield was establish.

The paper presents the results obtained on preluvo-soil in Sâniob, Oradea, during 2007-2015. In order to maintain the soil water content between easily available water content and field capacity, the irrigation rate used was between 60 mm/ha and 470 mm/ha. Irrigation determined an increase of the total water consumption by 53% (712 mm/ha vs. 466 mm/ha). For the non-irrigated variant (71%) and for the irrigated one (46%), the rainfalls registered between 15 March-1 October yearly represented the main source of supplying the total water consumption, while irrigation supplied 40% of the total water consumption (with a variation range 11%-61%). The microsprinkler irrigation system led to a 30.6% yield gain, with a variation range of 15.8%-58.7%. It also determined a higher size index in comparison with the non-irrigated variant and a smaller percentage of kernels. All differences were statistically very significant. Several correlations were quantified in the soil-water-plant-atmosphere system. The parameters of the system were: pedological drought, strong pedological drought and water consumption. All correlations were statistically very significant; the best mathematical expression was the polynomial function. Four methods (Penman Monteith, Pan, Piche and Thornthwaite evaporimeter methods) were studied to determine the reference evapotranspiration (ETo) in comparison with the optimal water consumption of the peach tree. As it was cheaper and easier to use, the Pan evaporation method was recommended in the irrigation scheduling, although the Penman Monteith method could have given more accurate results in assessing the optimal water consumption.