Abstract:
This study discussed the effect of different sugarcane intercropping patterns and nitrogen dosages on soils greenhouse gas emission and the related impact on crops yield. The study further strengthened the theoretical basis for measuring agriculture-based greenhouse gas emission. It analyzed emission fluxes of greenhouse gases (CO
2, N
2O and CH
4) in sugarcane//soybean intercropping systems with crops line ratios of 1∶1 (SB1) and 1∶2 (SB2), monocropped sole sugarcane(MS)under two nitrogen levels (N2, 525 kg·hm
-2 and N1, 300 kg·hm
-2) and monocropped soybean under zero nitrogen supply using the static chamber/gas chromatographic technique during the crop growth season. Results showed that compared to the sugarcane monoculture, cumulative emissions of CO
2 and N
2O in SB2 under low nitrogen dose (SB2-N1) respectively decreased by 35.58% and 56.36%. Also cumulative CH
4 emission increased by 7.02%. Soils in different cropping patterns and nitrogen dosages served as sources of CO
2 and N
2O, sink of CH
4 during crop growth season. After nitrogen application, CH
4 absorption rate decreased while CO
2 and N
2O flux rates increased. CO
2 emissions (kg·hm
-2·a
-1) under MS-N1, SB1-N1, SB2-N1, MS-N2, SB1-N2, SB2-N2 and MB treatments were 5 096.89, 6 422.69, 3 283.20, 4 103.29, 4 475.84, 4 775.31 and 4 780.35, respectively. Cumulative N
2O emissions (kg·hm
-2·a
-1) under MS-N1, SB1-N1, SB2-N1, MS-N2, SB1-N2, SB2-N2 and MB treatments were 4.61, 5.11, 2.15, 3.13, 3.72, 5.60 and 3.11, respectively. Also cumulative CH
4 emissions (kg·hm
-2·a
-1) under MS-N1, SB1-N1, SB2-N1, MS-N2, SB1-N2, SB2-N2 and MB treatments were 13.68, 21.78, 12.72, 5.53, 11.36, 4.77 and 9.97, respectively. Land equivalent ratio (
LER) values in sugarcane//soybean intercropping systems exceeded 1.0 during 2009 and 2012. The study showed that SB2 cropping system was the best one under low nitrogen conditions.