The present paper reviews the most recent advances regarding the effects of chemical and organic fertilizers on soil microbial communities. Based on the results from the articles considered, some details are presented on how the use of various types of fertilizers affects the composition and activity of soil microbial communities. Soil microbes have different responses to fertilization based on differences in the total carbon (C), nitrogen (N) and phosphorus (P) contents in the soil, along with soil moisture and the presence of plant species. These articles show that the use of chemical fertilizers changes the abundance of microbial populations and stimulates their growth thanks to the nutrient supply added. Overall, however, the data revealed that chemical fertilizers have no significant influence on the richness and diversity of the bacteria and fungi. Instead, the abundance of individual bacterial or fungal species was sensitive to fertilization and was mainly attributed to the changes in the soil chemical properties induced by chemical or organic fertilization. Among the negative effects of chemical fertilization, the decrease in enzymatic activity has been highlighted by several papers, especially in soils that have received the largest amounts of fertilizers together with losses in organic matter.
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Tomatoes, one of the most appreciated vegetables consumed, are crops well adapted for cultivation in arid and semi-arid conditions, with the success of large yields guaranteed by covering water consumption through irrigation. Solar Pumps—SP are driven by Photovoltaic Panels—PV (SPAPV), eliminating the dependence on electricity or diesel; they are environmentally friendly because they generate carbon-free electricity, and the cost of operation and maintenance is lower. In order to preserve the water administered by drip to the tomato crop grown in solariums, mulching is used. In Husasău de Tinca, in the Crișurilor Plain, the cultivation of tomato varieties without mulching (WM) and with mulching with black foil (MBF) was studied. To answer the question “How effective are water conservation measures in terms of energy independence?”, two variants of SPAPVs, direct pumping (ADP) and storage tank (AST) were simulated. It is proposed to determine the water consumption of tomatoes (ETRo), using the temperatures inside the solarium. In 2016, the average temperatures during the vegetation period with insurance of over 20%, were observed. The specific investment (SI) is 214,795 Euro ha−1 in the case of ADP and respectively 202,990 Euro ha−1 in the case of ATS. The payback period (IPT) is between 2.68 years and 2.53 years for the ADP variant and between 1.63 years and 1.54 years for the ATS variant. The indications for water use and irrigation water use show that in the MBF variant, the water administered by localized irrigation is better utilized than in the WM variant. The novelty of this study is the evaluation of the effectiveness of measures to reduce the effects of global climate change on tomatoes grown in solariums, useful for forecasting and watering restrictions, water consumption is determined from the air temperature measured inside the solarium, with insurance of over 20%. Taking into account the working hypotheses, the distribution of irrigation water in the solarium, with the help of SPAPVs, for tomatoes grown in the MBF variant, and a drip irrigation arrangement with ATS, the energy independence of the farm is ensured, the yields obtained are economically efficient, and the irrigation water is used rationally.
Abstract. This study was conducted to evaluate the variability of the chemical properties of the soil of an oak forest affected by defoliation and the corresponding microbial abundance. Soil samples were collected from a control zone (zone 1) without outbreaks of defoliating insects and from a sample zone (zone 2) where the trees were affected by Lymantria dispar L. defoliation. The research was conducted to determine the changed conditions for soil microorganisms produced as a consequence of defoliation. The results indicated, by means of analysis of variance (two-way ANOVA, P = 0.05), statistically significant differences (P < 0.0001) with respect to soil hydrolytic acidity, pH, ammonium nitrogen, heterotrophic bacteria, nitrogen fixing bacteria from genus Azotobacter and fungi. The data revealed a low number of heterotrophic bacteria and low pH values in samples taken from the area affected by defoliation. Soils under stands of defoliated trees showed higher values with respect to soil acidity, ammonium nitrogen, fungi and nitrogen fixing bacteria Azotobacter. Moreover, the soil moisture, nitrate nitrogen, organic matter content, organic carbon, the number of heterotrophic bacteria and the number of bacteria from genus Azotobacter exhibited statistically significant seasonal differences between the two zones studied. The correlations between the tested parameters showed that soil parameters such as moisture content, soil acidity, pH, organic matter content, organic carbon, total nitrogen and nitrate nitrogen are important factors influencing the soil populations of aerobic mesophilic heterotrophic bacteria, fungi and nitrogen fixing bacteria in the studied forest ecosystem.
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