Untitled - MendelNet 2013 - Mendelova zemědělská a lesnická ...

MENDELNET 2013The maximum capillary capacity (MCC):Another indicator of soil compaction is MCC (Fig. 4) .Fig. 4, The maximum capillary capacityIt has a critical threshold of 36%,values above this thresholdindicate a failure in the soilstructure (Pokorny, Střelková et al.1996). The greatest frequency ofexceedance of the critical value isin the topsoil and loess cover,where, on the second plot, thevalues were significantly high.40,0038,0036,00%34,0032,00The maximum capillary capacityDambořice 1Dambořice 2Klobouky u B.1Domanín30,00arable layer Aarable layer Barable layer Csubsoil Asubsoil Bsubsoil Cloess1-10 Aloess 1-10 BMinimum air capacity:Fig. 5, Minimum air capacityIf the minimum air capacity is lessthan 10 %, the subsoil or theMinimum air capacitytopsoil is in a critical condition(Pokorny, Šarapatka et al. 2007).20,00The graph (Fig. 5) implies that all18,00values of the topsoil on the top of16,0014,00Dambořice 1the slope are below the critical12,00Dambořice 2value, there is an improvement in % 10,00Klobouky u B.1the centre area of the plot, and at8,00Domanínthe foot area, it deteriorates again6,00on all but one plots. The subsoil is4,00mostly below the critical value.2,000,00The compaction means a severearable arable arablelayer A layer B layer CsubsoilAsubsoilBsubsoilCloess1-10 Aloess 1-10 Bdamage to the soil, in which itsvolume decreases, porosity is reduced and so is the space for water and air. According to Sommer(1990), the critical value of porosity for loamy soils is 45% , for bulk density it is 1.41 to 1.46 g.cm -3 and for minimum airiness it is 12% (Šarapatka, 2002).CONCLUSIONSFor the survey, plots with soil type chernozem on loess were selected,which were threatened by water erosion. On all the plots, impact of watererosion was evident, indicating very clearly a shift of soil particles intolocation below the slope. The topsoil on these plots is washed away insuch an extent, that there is an occurence of the loess in the upper part ofthe slope (Fig. 6).On these plots there is a wash-off of the topsoil in such an extent that inthe upper part of the slope the loess gets mixed with the topsoil during theplowing and sometimes the loess cover is completely exposed andgradually reclaimed. With continued erosion in the accumulative part ofthe slope, the dark topsoil is further overlaid with less fertile soil from theFig. 6299 | P age