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Biomedical subjects

B Novák

Publications and source records attributed to B Novák.

6 recordsLinked to original sources
PubMed1979

Influence of fluctuating temperature on soil microflora.

The effect of different constant and "square-wave" fluctuating temperatures on the soil microflora was studied in laboratory experiments. The growth of soil microorganisms was higher at lower temperatures, indicating the higher degree of substrate immobilization and the better energy economy of the soil bionta. Microbial counts were slightly higher after five days of incubation at fluctuating temperatures than those obtained at a constant mean temperature. It was important whether the fluctuation started at lower or at higher temperatures. At a fluctuating temperature the amount of nitrates decreased compared to the amount at a constant temperature. The development dynamics of soil microorganisms was accelerated by the fluctuation of temperature as judged by nitrogen transformation and simultaneous changes in microbial counts.

Nitrates↗
PubMed1978

Effect of moisture level on nitrogen immobilization as affected by wheat straw decomposition in soil.

Samples of a slightly degraded chernozem soil were amended with 2 per cent of wheat straw at three moisture levels (10, 20, and 30 per cent) and were provided with 160, 240, and 400 ppm of ammoniacal nitrogen. Amounts of total, ammonia, and nitrate were determined at different periods of incubation at 28 degrees C and immobilization of the total available nitrogen in the soil was calculated. Substantial amounts of the added nitrogen were immobilized in the soil as a result of the straw decomposition during the first month of incubation. The amount of inorganic nitrogen (NH4 + -N + NO3 - -N), bound within 75 days of incubation, was almost three times less than that immobilized within 30 days. Maximum quantity of nitrogen was immobilized at 30 and 20 per cent moisture levels at 30 and 75 days of incubation, respectively. Minimum immobilization was observed at 10 per cent moisture at almost all levels of nitrogen. The absolute amount of nitrogen immobilized increased in proportion to the quantity of nitrogen added, but the relative immobilization tended to decrease with the increased inorganic nitrogen the soil.

Humidity↗
PubMed1978

Effect of moisture and nitrogen levels on the decomposition of wheat straw in soil.

Two per cent of wheat straw was mixed with samples of a slightly degraded chernozem soil, and its decomposition was studied at 10, 20, and 30 per cent moisture content of the soil with the addition of 160, 240, and 400 ppm of NH4 + -N. The overall decomposition, measured as CO2 production, and total carbon loss from the soil at 28 degrees C was enhanced by the added nitrogen at all levels of moisture in proportion to the quantity added. Maximum mineralization of the straw carbon was observed at 30 per cent moisture content but there was no significant difference between the amount of carbon mineralized at 20 and 30 per cent moisture levels. No stabilization of the substrate took place in the soil except at 240 and 400 ppm of applied nitrogen at 30 per cent moisture level towards the end of the incubation period. More straw carbon was mineralized when the soil samples were subjected to daily measurements of CO2 evolved than when CO2 measurements were made at intervals over the same period of incubation.

Fermentation↗
PubMed1976

Simple method for carbon determination in microbiological experiments.

A wet combustion method for the carbon determination was developed. It has been proved that the method can be successfully used for the determination of biochemical changes in microbe cultures, the soil, in composts, in farmyard manures etc. The samples are combusted in evacuated flasks by means of chromic sulphuric mixture, and the CO(2) evolved is determined interferometrically.

Carbon↗