Study On The Effects Of No-till Wheat Rotated With Previous Maize Under Plastic Film Mulching On Water Saving And GHG Emission Reduction

In oasis irrigation agricultural region,the insufficient academic and technical support for study on water use and greenhouse gas?GHG?emissions in field has led to a great short slab on saving water and reducing GHG emissions simultaneously through the integrated application of crop rotation,no-tillage and film mulching by years in practices.A field experiment was carried out in 2015-2016 in order to investigate the water consumption and GHG emission during wheat whole growth period under two kinds of maize stubble management modes?NT: no tillage and plastic film mulching of previous stubble;CT: conventional tillage?,two irrigation levels?I2: conventional irrigation;I2: reduced 20% irrigation?and three nitrogen levels?N3:225kg ha-1;N₂:180kg ha-1;N1:135kg ha-1?.The purpose of the study focused on providing academic and practical evidence for saving water and reducing GHG emissions through optimizing managements of previous stubble.The main results are as follows:1.No tillage and plastic film mulching of previous stubble?NT?significantly increased the total water consumption?ET?,but the soil evaporation?E?and E/ET were significantly decreased.Similarly,reducing irrigation and nitrogen significantly decreased the ET,E and E/ET.As compared to conventional tillage treatment?CT?,the ET in NT treatment was increased by 3.8%,but both of E and E/ET were reduced by 17.6%and 27.4%.While as compared to traditional irrigation and nitrogen application treatment,the ET,E and E/ET under the low nitrogen treatment of reduced 20% irrigation level in NT were greatly reduced by 14.3%,13.7%and 17.7%.2.As compared to the CT treatment,the NT treatment significantly decreased the total CO₂ emission,but increased the total N₂ O emission.And the NT treatment further reduced the global warming potential?GWP?and the GHG emission of per unit water consumption,but improved the GHG emission efficiency.The GWP and the GHG emission of per unit water consumption in NT treatment were decreased by 12.1% and 17.7%,and the GHG emission efficiency was improved by 20.1%.In addition,As compared to traditional irrigation and nitrogen application treatment,reducing irrigation and nitrogen application treatment significantly decreased the CO₂ and N₂ O emissions in farmland with no tillage and plastic film mulching of previous stubble.the total CO₂ emissions of the NTI1N1 treatment was minimum,up to 3495.2kg ha-1,but the biggest decline of the total N₂ O emissions was 42.7% compared with the traditional irrigation and nitrogen levels.Similarly,reducing irrigation and nitrogen application treatment significantly decreased the GWP and the GHG emission of per unit water consumption in farmland with no tillage and plastic film mulching of previous stubble,but improved the GHG emission efficiency,and especially the GWP and per unit water consumption of GHG emissions of the NTI1N1 treatment were least among all treatments,which were 15637 kg CO₂eq and35.5 kg CO₂ eq mm-1,and the maximum of the GHG emission efficiency was 0.547 kg kg CO₂eq-1.3.The soil water content,inorganic nitrogen content and the dry matter accumulation in wheat field were significantly increased,and the soil temperature was decreased by the NT treatment.Similarly,soil moisture and soil temperature from seedling to grain filling stage in farmland with no tillage and plastic film mulching of previous stubble were significantly decreased by reducing irrigation amount.And both the inorganic nitrogen contetn and dry matter accumulation from seedling to booting stage were increased by reducing irrigation application,but it from booting to maturity stage was decreased by reducing nitrogen application.In addition,the correlation analysis showed that the GWP was positively related with soil respiration,soil temperature also was positively correlated with soil respiration rate,while soil moisture and inorganic nitrogen content also were positively correlated with the N₂ O emission rate.So reducing greenhouse gas emission rate by lower soil temperature,soil water content and the content of inorganic nitrogen is the basis of decreasing carbon emission in farmland.4.The NT treatment had no significant effect on yield and resource utilization efficiency,compared with the CT treatment.Similarly,decreasing irrigation and nitrogen amount significantly increased wheat yield,WUE,IWUE,NUR and PPNR in farmland with no tillage and plastic film mulching of previous stubble.In addition,the grain yield and its corresponding GWP is not significant correlation?p=0.271?,the variance calculation proved that it is possible to achieve stable yield on the premise of reducing GHG emission in wheat production.The new production pattern that combined no tillage and plastic film mulching of previous stubble with reduced 20% conventional irrigation?seedling,booting and filling stage respectively,60 mm,70mm,60 mm irrigation?and low nitrogen level?135kg ha-1?significantly increased wheat yield,WUE and NUR,by8%,8.9%,20.7%,and GWP decreased by 20.9%,compared with traditional production pattern.It is showed that the technology combination is one of the efficient production mode of saving water and reducing emission wheat in Oasis Irrigation district.