| The climate change caused by GHG is concern about the environment problems in the world today. GHG emissions has received extensive attention all over the world and further study. The sand covered as a local mulching measures, played a huge role in the Guanzhong area, get a lot of application in agricultural production.The paper mainly researches and analyzes the corresponding change rule of soil GHG based on field experiment of different sand coverage and different thickness of sand covered in winter wheat and summer maize in continuous cropping systems. The field experiment of winter wheat during 2013 to 2014 had three coverage levels as 0, 0.5, 1.0 and two irrigation levels 0, 50 mm, which resulted in six treatments(S0, S0.5, S1.0, WS0, WS0.5, WS1.0),while the field experiment of winter wheat during 2014 to 2015 had three levels of cover thickness as 0, 1, 4 cm and two irrigation levels 0, 50 mm, which resulted in six treatments(S0, S1, S4,WS0, WS1, WS4). The field experiment of summer maize in 2014 and 2015 had two levels of cover thickness as 0 and 4 cm, two irrigation levels 0, 50 mm, which consequently resulted in four treatments(S0, S1, WS0, WS1).The thesis analyzed the differences between different treatments and farmland GHG emissions under the influence of the main factors of GHG emissions. Some main conclusions have been drawn as follows:(1) Gravel cover played a significant role in promoting on CO2 emissions in the growth period of winter wheat. But with the increases of coverage and the thickness of the sand covered the total amount of CO2 emissions didn’t increase. The total amount of CO2 emissions of coverage 100% condition was smaller than coverage 50%, and the total amount of CO2 emissions of sand covering thickness 4 cm was less than 1 cm cover thickness while it was less than the total amount of CO2 emissions of 2 cm cover thickness. Under the condition of irrigation, Gravel cover played an important role in promoting on CH4 emissions, while with not irrigation Gravel cover played an important role in promoting on CH4 absorptions in the growth period of winter wheat. With the increases of coverage and the thickness of the sand covered the total amount of CH4 emissions or absorptions increase. Gravel cover played a significant role in promoting on N2 O emissions in the growth period of winter wheat. With the increases of coverage and the thickness of the sand covered the total amount of N2 O emissions increase. With the same Sand coverage and thickness of sand covering irrigation treatmentplayed a significant role in promoting on CO2 emissions, but didn’t play significant impact on the total amount of N2 O emissions.(2) Sand covered had the effect of the inhibition for CO2 and N2 O emissions but played an important role in promoting on CH4 absorptions in the growth period of summer maize in2014. Sand covered played an important role in promoting on CO2 and N2 O emissions in the growth period of summer maize in 2015. Under the condition of irrigation sand covered played an important role in promoting on CH4 emissions, while under the condition of no irrigation sand covered played an important role in promoting on CH4 absorptions in the growth period of summer maize in 2015. Irrigation had the effect of the inhibition for CO2 and N2 O emissions and CH4 absorptions.(3) The emissions of irrigation and sand coverage 50% characterized by sources of GHG,and other treatments characterized by of GHG in the growth period of winter wheat. Under the condition of irrigation the NGWP value of coverage 100% was more than no sand covered which was more than coverage 50%, while the NGWP value of sand covering thickness 4 cm was more than no sand covered which was more than sand covering thickness 1 cm. Under the condition of no irrigation the NGWP value of coverage 50% was less than coverage 100%which was less than no sand covered, while the NGWP value of sand covering thickness 1 cm was less than sand covering thickness 4 cm which was less than no sand covered. The influence of irrigation on NGWP value were not the same. Sand covered played an important role in increasing NGWP value. Under the condition of sand covered irrigation played an important role in increasing NGWP value, while it played an important role in decreasing NGWP value under the condition of no sand covered.(4) Soil temperature and air temperature had a significant positive correlation in the growth period of winter wheat and summer maize. With or not with wheat and maize the correlation among CO2 and CH4 and N2 O emission fluxes and soil temperature and air temperature and water content were not the same, respectively. The influence of soil temperature and air temperature and water content on CO2 and CH4 and N2 O emission fluxes were not the same, respectively. The temperature coefficient Q10 with or not with wheat of CO2 emission with soil temperature and air temperature were 2.43 and 2.78 respectively in the growth period of winter wheat during 2013 to 2014. The temperature coefficient Q10 with or not with wheat of CO2 emission with soil temperature and air temperature were 2.35 and 3.23 respectively in the growth period of winter wheat during 2014 to 2015.The temperature coefficient Q10 of soil respiration with soil temperature were 1.09 and 1.97 in the growth period of summer maize in 2014 and 2015, respectively.(5) It was increased the total amount of CO2 emissions while decreased the total amount of CH4 absorptions and increased the total amount of N2 O emissions with wheat in the growth period of winter wheat. Participating in maize lead to decreasing the total amount of CO2 emissions with or not with wheat. It resulted in increasing the total amount of CH4 absorptions with wheat, while it resulted in decreasing the total amount of CH4 absorptions not with wheat.Participating in maize lead to increasing the total amount of N2 O emissions with or not with wheat. |
PDF Full Text Request