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The objective of this study was to compare chemical and microbial properties of sandy mine soils under young Scots pine, silver birch, and mixed pine-birch forest stands. The measured properties included the contents of organic C (Corg) and total N (Nt), the Corg-to-Nt ratio, pH, microbial biomass, basal respiration, and activities of dehydrogenase, acid phosphomonoesterase, and urease. Community level physiological profiles (CLPPs) of soil bacteria were determined with BiologR test and genetic profiles with the DGGE method. Scots pine and silver birch did not affect the Corg and Nt contents in the studied mine soils. The soil under birch contained larger and more active microbial biomass than the soil under pine. Under the mixed stand, most of the microbial properties were intermediate between the pine and the birch stand. The DGGE profiling indicated different composition of soil bacteria under the birch stand compared to the other stands. Differences in CLPPs were less pronounced, probably due to functional redundancy of soil bacteria.
Studies performed in a field indicate that podzolic soil combined with sewage sludge under Salix viminalis L. cultivation exhibited an increase in lipolytic bacteria and fungi numbers as well as a clear stimulation of lipase activity at level A. These changes increased in accordance with the increase of sludge concentration in the soil, and remained in the second and the third year of the experiment. However, a decrease of lipase activity was observed in subjects with a higher sludge concentration in the third year. Disturbances of microbial and enzymatic soil properties after the addition of sewage sludge occurred less intensively at the 20-40 cm than the 0-20 cm layer. In general, a slight stimulation of lipolytic bacteria and fungi and a stronger stimulation of lipase activity was found with higher doses of sludge. As at level A, these changes remained active for two years, showing a decline of lipase activity in the third year.
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In the pot experiment the effects of contamination of diesel oil of proper brown soil developed from light loamy sand on microorganisms abundance and activity of soil enzymes were studied. Diesel oil was applied at the following rates: 0, 2, 4 and 6 cm3 kg-1 of the soil. Trial was performed in two experimental series: amended or not amended with straw. It was found that soil pollution with oil stimulated development of Azotohcicer sp., oligotrophia copiotrophic and ammonitiers bacteria; whereas inhibited fungi proliferation, dehydrogenases and urease activities and did not affect actinomycetes number. Diesel oil addition to the soil reduced positive effects of straw on microbiological and biochemical soil properties. Oil pollution adversely affected growth and development of triticale. Straw amendment diminished level of oil toxicity to triticale.
Studies on the comparison of microbial and biochemical characteristics of soils were based on a field experiment established in 1994 at the IUNG Experimental Station in Osiny on soil (loamy sand) belonging to complex IV. In this experiment spring barley and winter wheat were grown in three crop production systems: ecological, integrated and conventional. Soil under wheat were analysed in 1996, 1997 and 1998, and under barley in 1997 and 1998. Microbial biomass, numbers of bacteria and fungi, soil respiration and enzymes (dehydrogenase, phosphatases) activity were generally higher in the soil under the tested cereals grown in the ecological system than in the soil under these crops grown in the conventional or integrated system. These differences were detected during all three growing seasons, indicating long-lasting changes in the biological characteristics of the studied soil.
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