No abstract

Nitrifiers and denitrifiers are the main producers of the greenhouse gas nitrous oxide (N(2)O). Knowledge of the respective contributions of each of these microbial groups to N(2)O production is a prerequisite for the development of effective mitigation strategies for N(2)O. Often, the differentiation is made by the use of inhibitors. Measurements of the natural abundance of the stable isotopes of N and O in N(2)O have been suggested as an alternative for the often unreliable inhibition studies. Here, we tested the natural abundance incubation method developed by Tilsner et al.1 with soils from four European grasslands differing in long-term management practices. Emission rates of N(2)O and stable isotope natural abundance of N(2)O and mineral N were measured in four different soil incubations: a control with 60% water-filled pore space (WFPS), a treatment with 60% WFPS and added ammonium (NH(4) (+)) to support nitrifiers, a control with 80% WFPS and a treatment with 80% WFPS and added nitrate (NO(3) (-)) to support denitrifiers. Decreases in NH(4) (+) concentrations, linked with relative (15)N-enrichment of residual NH(4) (+) and production of (15)N-depleted NO(3) (-), showed that nitrification was the main process for mineral N conversions. The N(2)O production, however, was generally dominated by reduction processes, as indicated by the up to 20 times larger N(2)O production under conditions favouring denitrification than under conditions favouring nitrification. Interestingly, the N(2)O concentration in the incubation atmospheres often levelled off or even decreased, accompanied by increases in delta(15)N and delta(18)O values of N(2)O. This points to uptake and further reduction of N(2)O to N(2), even under conditions with small concentrations of N(2)O in the atmosphere. The measurements of the natural abundances of (15)N and (18)O proved to be a valuable integral part of the natural abundance incubation method. Without these measurements, nitrification would not have been identified as essential for mineral N conversions and N(2)O consumption could not have been detected.

The paper presents the results of a scientific project focused on limiting nutrient losses from farms by introducing measures to apply fertilizers in a more sustainable way. It is a case study of selected aspects of farm management, focussing on the issue of sustainable agriculture and their tools. The main aim of the study was to analyse and evaluate farmers’ knowledge of the fertilizing process and its aspects, as well as applying sustainable agricultural activities on farms. The study emphasised the importance of nutrient management, as very important for sustainable farming. Also, the links between farmers’ opinions and their activities were analysed. The important issue concerned measures for sustainable farm management introduced on the farms, as well as measures to limit nutrient leaching into groundwater. Twenty-eight farmers from two regions in Poland were interviewed about their perceptions for the case study. In general, the farmers considered their farm activities to be more sustainable than in the past. They demonstrated an understanding of the general idea of sustainable agriculture. However, many farmers still demonstrated a poor grasp of nutrient flows and nutrient balances on farms. Their knowledge and perception was based on general, rather than specific knowledge gleaned from an academic/vocational course. The farmers demonstrated a realization that there were some new, or low-cost measures that could be introduced to make management more sustainable and pro-environmental, but there was still a need for wider adoption of sustainable agricultural practices.

No abstract

Knowledge related to land-use management impacts on the Baltic Sea ecosystem is limited. The constant release of pollutants into water bodies has resulted in water quality degradation. Therefore, only the innovative approaches integrated with research will provide accurate solutions and methods for proper environment management and will enable understanding and prediction of the impacts of land-use in the Baltic Sea region. Modelling approaches have become essential to address water issues and to evaluate ecosystem management. There are many water quality models, but only a few work in the operational mode and only some of them can be used as an interactive tool for environmental management to assess the impact of pollution on water quality. This study presents a new approach for investigating the influence of pesticides and nutrient fluxes from agricultural holdings and land-use *