Yuchun Ma Jinyang Wang Wei Zhou Xiaoyuan Yan Zhengqin Xiong. Greenhouse gas emissions during the seedling stage of rice agriculture as affected by cultivar type and crop density. Biol Fertil Soils 2012 48:589–595.
Abstract
Methane (CH4) and nitrous oxide (N2O) emissions from a paddy nursery at the rice seedling stage were measured on a daily basis by using the conventional rice cultivar Nangeng 56 under both conventional (NG-C) and reduced (NG-R) sowing density and the hybrid rice Changyou 3 under both conventional (CY-C) and reduced (CY-R) sowing density. High N2O and CH4 emissions were observed
during the first and last 2 weeks respectively. Cumulative CH4 emissions were significantly (P<0.001) affected by sowing density rather than by the rice cultivar. Cumulative CH4 emissions reached 68.2 kg C ha−1 in the CY-C treatment and 121.6 kg C ha−1 in the NG-C treatment which were significantly (P<0.001) higher than the emissions at reduced sowing densities (15.9 kg C ha−1 in the CY-R treatment and 20.9 kg C ha−1 in the NG-R treatment). Under the conventional sowing density cumulative CH4 emissions during the seedling stage were comparable to data of ricegrowing season. Both the rice cultivar and the sowing density significantly (P<0.05–0.01) affected cumulative N2O emissions. Relative to the CY cultivar the NG cultivar increased global warming potential (GWP) over a 100-year horizon by 62.1% and 70.7% under the reduced and conventional sowing densities respectively. The GWP of N2O and CH4 during the seedling stage was equivalent to the GWP of the entire ricegrowing season in this region indicating that the seedling stage is an important greenhouse gas emission source of rice agriculture.
