4. Conclusions
This study intended to evaluate the impact of biochar
amendment on some of the physical and hydraulic properties of
a clay soil. Equivalent hydraulic conductivity values were obtained
for unamended and amended soils for both saturated and
unsaturated hydraulic conductivity at the same pressure head.
Independent of the values of initial soil wa te r content, higher K
fs
values were always detected for the highest biochar concentration,
following the sequence C30 > C5 > C0 > C20 > C10. The relative
changes to the control between amended and unamended soils
ranged between 8%/+18% and 7%/+32%, respectively for low and
high u
i
values. Relatively similar results were obtained under
unsaturated conditions, although the higher K(h ) values were
detected for the unamended soil (C0 > C30 > C10, and max
RC = 61%). Significant increases of soil water retention were
observed only close to water saturation (i.e., 0 < h < 10 cm) for the
highest biochar concentration, C30. For the latter, the RC value of
saturated water content wa s equal to +11%. Soil amendments also
appreciably modified the capacitive indicators. The highest biochar
concentration significantly increased macroporosity and air
capacity, as well as significantly decreased available water and
relative fi eld capacity. Similar findings were obtained for C10, but
only for P
mac
. In line with the reference values in the literature and
for the studied clay soil, our results show that an excessive
concentration of biochar may cause an imbalance between the
liquid and gaseous phases. This can be clearly seen from relative
fi eld capacity results, since detected RFC values were lower than
4. ConclusionsThis study intended to evaluate the impact of biocharamendment on some of the physical and hydraulic properties ofa clay soil. Equivalent hydraulic conductivity values were obtainedfor unamended and amended soils for both saturated andunsaturated hydraulic conductivity at the same pressure head.Independent of the values of initial soil wa te r content, higher Kfsvalues were always detected for the highest biochar concentration,following the sequence C30 > C5 > C0 > C20 > C10. The relativechanges to the control between amended and unamended soilsranged between 8%/+18% and 7%/+32%, respectively for low andhigh uivalues. Relatively similar results were obtained underunsaturated conditions, although the higher K(h ) values weredetected for the unamended soil (C0 > C30 > C10, and maxRC = 61%). Significant increases of soil water retention wereobserved only close to water saturation (i.e., 0 < h < 10 cm) for thehighest biochar concentration, C30. For the latter, the RC value ofsaturated water content wa s equal to +11%. Soil amendments alsoappreciably modified the capacitive indicators. The highest biocharconcentration significantly increased macroporosity and aircapacity, as well as significantly decreased available water andrelative fi eld capacity. Similar findings were obtained for C10, butonly for Pmac. In line with the reference values in the literature andfor the studied clay soil, our results show that an excessiveconcentration of biochar may cause an imbalance between theliquid and gaseous phases. This can be clearly seen from relativefi eld capacity results, since detected RFC values were lower than
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