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  • Author or Editor: M. Tállai x
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In a long-term fertilization field experiment set up in Debrecen-Látókép in 1983 on calcareous chernozem soil the changes in the chemical and microbiological characteristics related to the carbon and nitrogen cycles of the soil are shown and evaluated. The soil samples were taken in the 26th and 27th years of the experiment, (in 2009, 2010) from maize monoculture and tri-culture. In addition to the effects of fertilizer doses, correlations among soil chemical and microbiological properties were established; and the various ratios among some microbiological parameters were also evaluated.The elements of NPK fertilizers increased together with the doses, so the elements’ effect cannot be separated, the minimum factor is not identifiable.With increasing fertilizer doses, the soil pH decreased in both the mono- and triculture, parallelly there was a significant increase in hydrolytic acidity. A close negative correlation was proved between the pH(H2O) and hydrolytic acidity and pH(KCl) and hydrolytic acidity. An increased soil nutrient content was recorded in each NPK treatment, the available phosphorus and nitrate content increased in a higher proportion than that of potassium.Among the measured parameters of the carbon and nitrogen cycles fertilization had a positive influence on the organic carbon (OC), organic nitrogen (ON), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) contents, the number of cellulose decomposing and nitrifying bacteria, the nitrate exploration and CO2-production, while it mainly had negative effects on the investigated enzymes (saccharase and urease) activity.Evaluating the ratios among the measured parameters, fertilization seems to have promoted the increase in nitrogen-containing organic compounds, because the OC/ON and MBC/MBN ratios decreased due to the effect of different doses of NPK fertilizers in both cultures.

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In a pot experiment the effect of bentonite and zeolite doses [0; 5; 10; 15 and 20 g·kg soil -1 ] was studied on some chemical properties and ten soil microbiological and enzymological properties of an acidic [pH(H 2 O) = 5.65] humic sandy soil [WRB: Lamellic Arenosol (Dystric)], as well as on the biomass of perennial ryegrass ( Lolium perenne L.), as test plant. The pot experiment was set up in 2007 and 2008 at the Department of Agrochemistry and Soil Science of the Debrecen University in three replications. The average results of the two year experiment can be summarized as follows: The pH increased due to the effect of small and medium amendment doses. The bentonite treatments proved to be more effective than the zeolite doses. As the pH increased, the hydrolytic acidity – in case of the bentonite treatments significantly – decreased. Concerning the easily available nutrient content of soil, the small and medium amendment doses turned out to be effective. The large bentonite doses reduced the nitrate-N content, the easily available phosphorus and potassium contents of soil. Large dose zeolite treatments decreased the nitrate-N content, but increased both the phosphorus and potassium content of soil, in most cases significantly. Regarding the measured soil microbial parameters, the small and medium amendment doses were the most effective. The bentonite and zeolite treatments increased the biomass of perennial ryegrass, especially the small and medium doses of bentonite and the large dose of zeolite brought about significant increases. According to the statistical analyses moderate and close correlations were found between the parameters studied. In the bentonite treatments a close correlation was established between the aerobic cellulose decomposing bacteria and saccharase enzyme activity (r = 0.864) of soil. In the case of zeolite treatments, a close correlation was found between the number of nitrifying bacteria and microbial biomass C (r = 0.911) of soil.

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