Effects of Drought on Microbial Activity in Rhizosphere, Soil Hydrophobicity and Leaching of Mineral Nitrogen from Arable Soil Depending on Method of Fertilization

This work presents the first results from the long-term laboratory experiment dealing with impact of drought on soil properties. Three groups of the treatment (A, B and C) with different regime of irrigation were prepared. The soil water content was maintained at 70 % of soil water holding capacity in group A, at 40 % in group B. In group C, soil water regime was maintained in the range of wilting point. Each group of the experiment was divided into three variants (A1 = B1, C1; A2 = B2, C2 etc.) with three repetitions: Variants A1 (B1, C1) were controls without addition of another fertilizer. Variants A2 (B2, C2) were fertilized with mineral nitrogen fertilizer DAM 390 (0.140 Mg of N per ha) and variants A3 (B3, C3) contained 45 g of Cp per a pot. The significant differences (ANOVA, P<0.05) in the leaching of mineral nitrogen and values of saturated hydraulic conductivity (Ksat) were found. The highest values of Ksat were found in variants (within each group) with addition of compost (A3, B3, C3). Conversely, the lowest values of Ksat were found in variants with addition of mineral nitrogen. Low values of Ksat indicate an increased level of hydrophobicity in individual groups of the experiment. Moreover, all variants with compost addition showed lower amount of mineral nitrogen leaching and high level of microbial activity than variants without. This decrease of mineral nitrogen leaching was about 200 % in comparison with the control variant and about 300 % with variant, where mineral nitrogen was added. Based on these results, we can conclude that changes of soil water content directly have impact on microbial activity, soil hydrophobicity and loss of mineral nitrogen from the soil

The effect of small amounts of nitrate nitrogen on N.sub.2./sub.O emissions at two soils at overwintering area with different animal impact

The objective of this study was to examine short term effect of nitrogen addition into soil on emissions of N.sub.2./sub.O in two soils of overwintering area differently affected by cattle (M and C soils). The nitrate-N amendment increased emissions of N.sub.2./sub.O from soils, and in all three experiments, this effect was more pronounced in soil at location M, characterized by higher intensity of cattle traffic, according to our hypothesis. Cumulative production of N.sub.2./sub.O was proportional to the amount of nitrogen added at both locations, but it was more affected by soil NO.sub.3./sub..sup.-./sup.-N content than by the amount of nitrate added

Dynamics of N2O emissions after C and N amendments of soil at the cattle overwintering area

Field experiments were carried out at the cattle overwintering area in South Bohemia, Czech Republic, focused on the emissions of N2O after soil amendments with nitrate and glucose. Emissions were estimated using a permanent static chamber technique. Nitrate and glucose amendments caused very sharp increases of N2O fluxes, which however diminished after 2-3 days. Total amount of N2O escaping the soil was related to the amount of N and C added, and was calculated to 1-15 kg N.ha-1 (0.2-3% of N applied). Emissions were heterogeneous, which is shown by great differences among the individual chambers. Emissions were variable in time and very probably were controlled by temperature, as they approximately followed the air and surface soil temperature patterns. Despite the timing of amendment application, peaks of emissions were always determined 6 hours after the amendments

Symptomes of nitrogen excess in soil

Nitrogen cycling is one of the most important processes on the Earth. Most of N transformations run in soil. Nitrogen usually enters the soil as occasional input in concentrated forms which means that it is often in excess or in deficit. However, deficit and excess of N have different value in different soils and ecosystems. For example, amount of N which causes significant impact on ecosystem of spruce forest is insufficient for the maize field. This suggests, that the amount of N in soil must be evaluated in context of the whole ecosystem. In N-limited ecosystems, most of N is stored in plant biomass and litter characterized by slow transformations. Productivity of ecosystem is low, but N is utilized with high efficiency. On the other hand, in conditions of high availability of N, losses take place. These differences are reflected in content of different fractions of soluble N in soil and different rates of their transformations

Plant-soil nitrogen, carbon and phosphorus content after the addition of biochar, bacterial inoculums and N fertilizer

ACLOThe use of biochar in combination with mineral or biological amendments in order to improve its influence on soil-plant properties has received growing attention. The changes of N, C and P content in Lactuca sativa var. capitata aboveground plant biomass and soil after the addition of beech wood biochar combined with the addition of bacterial inoculums (Bacofil and Novarefm) and N fertilizer have been studied using spectrophotometry methods. Pots were filled with the arable soil from the plots in protection zone of water sources (Březová nad Svitavou, South Moravia, Czech Republic). Biochar with inoculums decreased plant growth in the first yield of Novaferm treatment and in both yields of Bactofil treatment. Increased plant biomass growth was observed with Novaferm addition in the second yield. Total N increase has been obtained in the plant aboveground biomass and soil of the treatments amended with inoculums and nitrogen fertilizer. The decrease of P content has been observed in plant aboveground biomass in the biochar amended samples

Soil Microbial and Physicochemical Changes After the Addition of Biochar, Bacterial Inoculums and Nitrogen Fertilizer

Addition of biochar is often proposed as an improving agent of soil properties. The combination of biochar (BCH) with mineral or biological amendments in order to improve its influence on soil-plant properties compared to the unamended BCH was vastly studied. Bacterial inoculums as a promising additive to BCH amendment are highly dependent on BCH quantity, its feedstock and soil state. Luvisol from a protection zone of water sources was used in pot experiment set-up. The changes in physicochemical properties (pH, cation-exchange capacity - CEC) and biological soil activities (soil enzymes: urease, phosphatase and laccase activity and total bacteria content) after the addition of beech wood biochar combined with the addition of bacterial inoculums (Bacofil and Novarefm) and nitrogen fertilizer after two growing cycles of Lactuca sativa var. capitata were studied using spectrophotometry methods. Increased pH and CEC values were detected in biochar amended treatments. The increase of laccase activity claimed on BCH additives promoting effect, especially in a case of Bactofil inoculum amendment. Nevertheless, BCH suppressed acid phosphatase activity in all the BCH additives equally. Whereas urease activity and total soil bacteria extraction remained unchanged in BCH amended treatments compared to control