ASSESSMENT OF SOIL QUALITY IN CONSERVATIVE AGRICULTURE SYSTEMS VERSUS CONVENTIONAL AGRICULTURE

The paper presents the results of the researches carried out in the SCDA Drăgăneşti Vlaşca experimental field, in two agriculture systems, conservative and conventional. Soil samples, taken in two phases, were analyzed in the laboratory to determine physical and chemical parameters: organic matter content, soil structure, bulk density, soil reaction, nutrients (N, P, K, and S) contents, total porosity, and resistance to penetration. Micro biological analyses were also performed: total number of bacteria (TNB´106/g dry soil), total number of micro fungi (TNF´103/g soil), and soil respiration (mg CO2/100 g sol). Soil arrangement state assessed through BD, TP, and RP is more favorable in the case of the conservative system as compared to the conventional one. The analyzed indicators highlight a soil looser arrangement in the conservative system and a certain improvement of the air condition. The slightly positive effects determined by the conservative system application reflect upon the soil hydric and physical state, and a little better conditions are present for water accumulation in soil. Diminished surface traffic permitted the so-called `soil rest` resulting in a natural soil aggregates re-arrangement and a slight improvement of the air-water system. From the chemical point of view the soil in both agriculture systems presented characteristics relatively favorable for growth and evolution of cultivated plants. From the micro biological point of view an increase of the TNF values was noticed at the spring harvest 2017 in two of the three probes made in the soil worked in conservative system as compared both to the autumn harvest and the conventional system, due to the nutrients abundance proceeded from the vegetal biomass left at the soil surface after harvest. Soil respiration as a soil biologic activity indicator closely modelled the TNB and TNF values obtained in both agriculture systems and in both harvest periods, proving that the soil microorganisms` populations are really active and develop their metabolic and ecologic functions in the soil

USE ORGANIC FERTILIZERS IN THE MODERN AGRICULTURE

The paper presents a synthesis of soil fertilization technologies, practices, methods, and measures that can be applied by each farmer within his farm, depending on the local specificity, respecting the environmental protection. Intensive farming with high yields requires large amounts of nutrients that the Romanian soil, even the most fertile, cannot fully provide, being absolutely necessary to supplement it with fertilizers.A part of the applied fertilizers are not consumed by crops and can be lost through surface leakage or infiltration water, which can result in aquatic system pollution. Intensification of agriculture by using both organic and mineral nitrogen-based fertilizers has caused surface waters eutrophication and the accumulation of nitrates in drinking water sources, which can generate serious effects on human and animal health.Adopting the environment-friendly agricultural technologies means both increasing the farmers' interest in the use of organic fertilizers and, implicitly, increasing the requested quantities.The manure used for centuries in agriculture obviously cannot ensure this necessity, which has led to intense research to find new compostable raw materials for the production of new fertilizers to provide nutrient needs for crops, safe and environmentally friendly.According to the Rural Development Regulation no. 1305/2013, at least 30% of the European Agricultural Fund for Rural Development is dedicated to measures that contribute to the achievement of environmental and climate objectives, biodiversity conservation, natural resources protection (especially soil and water), greenhouse gas emission reduction, traditional landscape conservation and agri-environment policies will be implemented through National Rural Development Program 2014-2020

ASSESSEMENT OF SOILS POLLUTED WITH HEAVY METALS FROM EMISSIONS EIGHT YEARS AFTER THE DOICEŞTI THERMAL POWER PLANT CLOSURE

Build in 1953 in Dâmboviţa County on 40 hectares, the Doiceşti thermal power plant worked based on combustion of the brown coal extracted from the Şotânga – Filipeşti mining area. It was developed in multiple stages up to two groups by 200 MW installed in 1979. In 2009, because of the high operating costs and environmental issues, the Doiceşti thermal power plant has ceased operation. For assessing the effects on the soil in the area influenced by emissions released by thermal power plant exhaust chimneys, a field study was carried out in 2000 year, when soil samples were collected on 0-20 and 20-40cm depths from surveys placed on the cardinal directions, depending on the relief and the dominant winds. Samples have been analyzed to determine their main physico-chemical properties and heavy metals contents. In 2017, after eight years since the thermal power plant has been closed, another field study in the same surveys was carried out, in order to assess the new state of soil quality and heavy metals contents. Data recorded in 2017 as compared with 2000 show a decrease of the Pb, Cd, Co and Ni contents in most surveys, confirming basically that the emissions from the thermal power plant were the main source of soil loading with these heavy metals. Regarding the contents of Zn and Cu, that in normal concentrations are important nutrients for plants, they increased in many surveys after the thermal power plant shuting down, indicate as source of these increases the fertilizers used by landowners

Evaluation of in vitro corrosion resistance and in vivo osseointegration properties of a FeMnSiCa alloy as potential degradable implant biomaterial

In vitro electrochemical characterization and in vivo implantation in an animal model were employed to evaluate the degradation behaviour and the biological activity of FeMnSi and FeMnSiCa alloys obtained using UltraCast (Ar atmosphere) melting. Electrochemical characterization was based on open circuit potential measurement, electrochemical impedance spectroscopy and potentiodynamic polarization techniques while the alloys were immersed in Ringer's solution at 37 °C for 7 days. Higher corrosion rates were measured for the Ca-containing material, resulting from inefficient passivation of the metal surface by oxy-hydroxide products. In vivo osseointegration was investigated on a tibia implant model in rabbits by referring to a standard control (AISI 316 L) stainless steel using standard biochemical, histological and radiological methods of investigation. Changes in the biochemical parameters were related to the main stages of the bone defect repair, whereas implantation of the alloys in rabbit's tibia provided the necessary mechanical support to the injured bone area and facilitated the growth of the newly connective tissue, as well as osteoid formation and mineralization, as revealed by either histological sections or computed tomography reconstructed images and validated by the bone morphometric indices. The present study highlighted that the FeMnSiCa alloy promotes better osteoinduction and osseconduction processes when compared to the base FeMnSi alloy or with AISI 316 L, and in vivo degradation rates correlate well with corrosion resistance measurements in Ringer's solution