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Soil water retention (SWR) is an important soil property related to soil structure, texture, and organic matter (SOM), among other properties. Agricultural management practices affect some of these properties in an interdependent way. In this study, the impact of management-induced changes of soil organic carbon (SOC) on SWR is evaluated in five long-term experiments in Europe (running from 8 up to 54 years when samples were taken). Topsoil samples (0–15 cm) were collected and analysed to evaluate the effects of three different management categories, i.e., soil tillage, the addition of exogenous organic materials, the incorporation of crop residues affecting SOC and water content under a range of matric potentials. Changes in the total SOC up to 10 g C kg−1 soil (1%) observed for the different management practices, do not cause statistically significant differences in the SWR characteristics as expected. The direct impact of the SOC on SWR is consistent but negligible, whereas the indirect impact of SOC in the higher matric potentials, which are mainly affected by soil structure and aggregate composition, prevails. The different water content responses under the various matric potentials to SOC changes for each management group implies that one conservation measure alone has a limited effect on SWR and only a combination of several practices that lead to better soil structure, such as reduced soil disturbances combined with increased SOM inputs can lead to better water holding capacity of the soil.

The content of nitrate or mineral nitrogen (N_min = N-NO^-₃ + N-NH ⁺₄) in soil in autumn is recognized as the indicator of potential risk of N leaching during winter. In this contribution, the apparent changes of N_min in the 0–60 cm soil layer, during winter, on farm fields in the Czech Republic were calculated. A significant positive relationship between N_min in autumn and the change during winter was observed in eight out of the nine farms. Nitrate N data produced similar relationships as N_min. The regression analysis suggested that 40–90% of N_min above a specific amount, 14–35 kg N/ha (interception of regression line, I1), on farms was apparently lost from the soil zone. Corresponding results for pooled data (n = 187) were 74% and 25 kg N/ha (r = 0.90, P < 0.001). The proportion of N leached from the 0–60 cm layer, calculated with a simple leaching equation was significantly correlated (n = 187, r = 0.92, P < 0.001) with observed N_minchange during winter, with the intercept (I2) significantly different from zero (–30.9 kg/ha). When the average value of regression intercept I1 of farms, or of pooled data, were introduced to the leaching equation as a constant correction parameter, the fit was satisfactory (r = 0.93 and 0.92, resp.) and the intercepts (–3.1 kg and –5.4 kg N/ha, resp.) were not significantly different from zero (at P < 0.01). The results of the study support the use of autumn N_min within the leaching equation as a robust indicator of the risk of N leaching.

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The field experiment with different soil tillage treatments has been carried out in Prague-Ruzyně locality (Czech Republic) since 1995. Data of two growing cycles in the years 2007-2010 and 2011-2014 were evaluated. Tillage technique was decisive for changes in soil characteristics and crop yields. Bulk density, organic carbon (C org ) and microbial biomass C (C mic ) were more equilibrated throughout all tested soil layers (0-0.1; 0.1-0.2 and 0.2-0.3 m) in conventional tillage (CT). In reduced tillage (RT) and no-tillage (NT) treatments significant accumulation of C org and increase of C mic in the surface layer were found, compared to CT. No significant differences in C org and C mic between two growing cycles were determined; however, mostly higher values were obtained in the top layer of NT during the second growing period. Higher bulk density under conservation tillage techniques did not negatively affect soil characteristics and should be taken in consideration for data evaluation as it can alter interpretation of their changes in the soil profile. Crop yields were comparable in CT and RT. Yield decrease in NT was mostly observed for winter wheat and pea. Beneficial effects of RT and NT conserving soil moisture on crop yield were not observed in dry years.