soil - Lublin

ture (Ball et al., 1999) and soil wetness and crop type (Franzluebbers et al., 1995).
CO 2 emissions after plowing were substantially higher from an established bermudagrass
pasture compared with a no-till sorghum field or a continuously cultivated
sorghum field (Reicosky et al., 1997). In addition minimum and no-till contributed
to lower CO 2 compared to CT fluxes due to reduced fossil-fuel consumption C
emissions associated with reduced number of farming operations (Sánchez et al.,
2002; West and Marland, 2002).
The effect of tillage on CO 2 emissions is associated with depth of soil disturbance
and equipment used. The data in Table 1 indicate that CO 2 fluxes immediately
after tillage (30-60 s) to 5-8, 10 and 45 cm depths were respectively 1.3, 4
and 7 times greater than that from non disturbed control plot (0.079 CO 2 -C m -2 h -1 ).
However, in study comparing various tillage implements (rotary tiller, chisel
plough, disk plow and disk harrow) with the same working depth (20 cm) the
fluxes were highest after applying disk harrow and in general increased with degree
of soil disturbance. Response of CO 2 emissions to tillage is more pronounced in
organic than mineral soils (Maljanen et al., 2001). The results stress the importance
of no disturbing practices in order to reduce soil carbon loss induced by tillage
treatments
Mechanisms
Greater flux from the soil during and shortly after tillage is often ascribed to
lower resistance to gas transfer and related physical CO 2 release from soil pores
and solution (Reicosky et al., 1997; Wuest et al., 2003). Other studies (Calderón et
al. (2001) and Jackson et al. (2003) reporting greater CO 2 emissions from disturbed
than non-disturbed in spite of lower respiration sustain this explanation. The CO 2
degassing from soil profile immediately after tillage can be pursued by increased
soil respiration when temperatures are warm and eagerly decomposable organic
matter or crop residue are available (Rochtte and Angers, 1999). When intense
rainfall occurred immediately after tillage and reduced greatly soil roughness, significantly
greater CO 2 -C emission in plowed compared to unplowed soil appeared
only few days later (Alvarez et al., 2001).
In some other studies, however, a diminishing effect of soil disturbance on CO 2
emission was also observed (Franzluebbers et al., 1995; Calderón et al., 2000) and
was attributed to the effects of different soil temperature and soil water content on
soil CO 2 evolution (Franzluebbers et al., 1995). In study of Kiese and Butterbach-
Bahl (2002) CO 2 emission was positively related to water filled pore space at dry to
moderate soil wetness during the dry season and negatively to the wetness changes
in the wet season. In sandy soils lower CO 2 emission from tilled vs. untilled plots
was attributed to low concentration of C and N and microbial activity (Calderón et
al., 2000).
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