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Joint International Conference on Long-term Experiments ...

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Nitrous-oxide emissi<strong>on</strong><br />

Nitrous-oxide emissi<strong>on</strong> was influenced significantly (P=0,05) by soil temperature and<br />

soil moisture c<strong>on</strong>tent. Am<strong>on</strong>g the three tillage treatments chisel plowing resulted in the<br />

highest nitrous-oxide emissi<strong>on</strong>, and there was no significant difference between<br />

moldboard plowing and no-till, so these latter treatments were c<strong>on</strong>sidered as <strong>on</strong>e group<br />

<strong>on</strong> the figures. Am<strong>on</strong>g crop rotati<strong>on</strong>s, corn m<strong>on</strong>oculture had higher values than<br />

soybean-corn rotati<strong>on</strong>, however these differences were not significant. Figure 2 shows<br />

the predicted and actual values of N2O emissi<strong>on</strong> influenced by soil temperature and soil<br />

moisture c<strong>on</strong>tent in soybean-corn rotati<strong>on</strong> and in corn m<strong>on</strong>oculture.<br />

N 2 O flux (mg/m 2 /hr)<br />

70<br />

60<br />

50<br />

40<br />

30<br />

20<br />

10<br />

0<br />

-10<br />

20<br />

22<br />

24<br />

26<br />

28<br />

30<br />

Soil temperature ( o C)<br />

N 2 O emissi<strong>on</strong> (mg/m 2 /hr) CH vs PL+NT<br />

80<br />

70<br />

60<br />

50<br />

Soil moisture (%)<br />

40<br />

30<br />

20<br />

Pred Moist vs Pred Temp vs CH Pred<br />

Pred Moist vs Pred Temp vs PL-NT Pred<br />

CH Moist vs CH Temp vs CH N2O<br />

PL-NT Moist vs PL-NT Temp vs PL-NT N2O<br />

Figure 2. Actual and predicted values of N2O emissi<strong>on</strong> in soybean-corn rotati<strong>on</strong> and<br />

in corn m<strong>on</strong>oculture (effect of tillage treatments)<br />

Regressi<strong>on</strong> equati<strong>on</strong>s (R 2 = 0,282134):<br />

79

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