Joint International Conference on Long-term Experiments ...

CH BC N2O = - 8,839 + 0,6904 * Moist – 0,0125 Moist * Temp
CH CC N2O = - 8,839 + 0,6904 * Moist – 0,0114 Moist * Temp
PL + NT BC N2O = - 8,839 + 0,5961 * Moist – 0,0125 Moist * Temp
PL + NT CC N2O = - 8,839 + 0,5961 * Moist – 0,0114 Moist * Temp
Carbon-dioxide and nitrous-oxide emission declined further in the growing season,
mainly, because the amount of nutrients necessary for microbial activity
(undecomposed crop residues and nitrogen fertilizer) has declined in the soil with time.
Nitrous-oxide emission increased after application of nitrogen fertilizer and after heavy
rain events (approximately 30-40 mm). Corn monoculture seems to give the highest
emission of carbon-dioxide, and also for nitrous-oxide, rotations including corn or corn
monoculture have the highest emission. As for tillage treatments, chisel plowing results
in the highest emission of nitrous-oxide.
Based on the results of our study from 2002-2004 we concluded that tillage effects
are more important in organic carbon and nitrogen storage than crop rotation effects.
We have found, that despite the 30 % higher total crop residue returned in continuous
corn, the soybean-corn and continuous corn rotations resulted in similar organic carbon
and nitrogen levels. The greater CO2 and N2O emission in continuous corn relative to
soybean-corn rotation explains the similar organic carbon and nitrogen storage under
the two crop sequences.
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