| Maize straw is an important agricultural resource that can be recycled because it is rich in a lot of carbon and nitrogen elements and other trace elements.Reasonably returning straw to the field can increase soil organic matter and provide necessary nutrient elements for the growth and development of crops.Studies have confirmed that straw returning to the field can not only improve crop yield,but also increase soil organic carbon,which is an important means to improve soil fertility.Plastic mulching is widely used in arid-semi-arid rain-fed agricultural areas because it can meet the demand of soil temperature and moisture for crop growth due to its good effect of increasing temperature and preserving soil moisture.However,the long-term use of plastic mulching film is likely to lead to the decline of soil quality,the reduction of organic carbon,and then cause crop production,which has become an urgent problem to solve in the long-term development of plastic mulching agriculture.Biodegradable mulching film,as a kind of non-polluting and easily degradable agricultural material,has received continuous attention in recent years.In the semi-arid rain-fed agricultural area,can we realize the transformation of plastic mulch agriculture from common plastic mulch to biodegradable plastic mulch? How to judge the strength and weakness of the transformation? There are few relevant studies at present.Can straw returning combined with biodegradable film mulching achieve the coupling of the two advantages,and achieve the effect of increasing crop yield,carbon fixation and emission reduction in semi-arid regions? It needs research to confirm.In view of the above problems,this study adopted the method of biodegradable plastic film combined with straw returning in the semi-arid spring corn field,and judged the feasibility of biodegradable plastic film combined with straw returning in the semi-arid region through crop yield,soil organic carbon content and changes,farmland greenhouse gas emissions and other agricultural economic and environmental benefit indicators.This research in 2019-2020 in Ningxia Peng Yang experimental station in northwest agriculture and forestry university of science and technology,test sets of four processing,returning for the culture(CK)respectively,and the culture of straw counters-field set(S),biodegradable film not double corrugation on the straw countersfield set(D),biodegradable film covering double corrugation on straw returned(DS),returning the main research content includes different coating line,spring maize yield,soil water heating,soil organic carbon content and reserves,agricultural greenhouse gas emissions and so on,the main results are as follows:(1)The plastic film mulching treatment effectively stored the natural precipitation in the fallow period,the soil water storage capacity before 0-200 cm sowing was significantly higher than that without plastic film mulching treatment,and the straw returning significantly improved the soil water storage and soil moisture conservation capacity.The soil water storage capacity before DS mulching was significantly 4%higher than that of D,while the situation of S and CK was the opposite.Straw returning significantly improved soil physical and chemical properties and increased soil moisture content in deep layers(especially 60-100 cm).To harvest,the soil water storage of 0-200 cm in each treatment increased to different degrees compared with that before sowing,with the size of CK>S>D>DS,the increase was 54.36-100.03 mm,and the water content of deep soil(60-200 cm)was mainly increased.(2)The trends of 0-20 cm hourly temperature change were consistent among different planting methods.Delayed the soil response to the temperature of plastic film mulching,prolong the time of warming,alleviate the cool night,reduces the temperature difference between day and night,straw returned to further optimize the effect,different treatment effect of warming,according to the soil deepen with DS processing temperature effect was most pronounced in the 0 to 10 cm,T average increase the daily average temperature 3.3 ℃,the DS,D and S in the night average temperature 1.4 ℃,1.7 ℃,0.46 ℃ and 3.7 ℃,3.5 ℃ and 0.5 ℃.(3)0-1 m,the soil organic carbon content of each treatment increased first and then decreased with the soil depth deepening,and the range of organic carbon content was 10.61-8.12 g kg-1(DS),10.34-7.44 g kg-1(D),10.24-8.6 g kg-1(S)and 10.47-8.69 g kg-1(CK),respectively.The highest values of organic carbon of DS and D,S and CK appeared at 60-80 cm and 40-60 cm,respectively.Straw returning treatment significantly increased the content of organic carbon,the size of which showed as DS>S>CK>D,where DS was significantly higher than other treatments(P>0.05).The total organic carbon storage within 0-1 m,DS,D,S,CK(P>0.05),130.99,123.49,131.89 and 124.09 Mg C ha-1,respectively.DS and S were significantly higher than D and CK.Under the same straw returning condition,biodegradable film mulching had no significant difference in total organic carbon storage.(4)In 2019,the yield of DS was only 1.76% higher than that of D,and straw returning had no significant effect on the yield difference between treatments under the same film mulching condition.In2020,DS significantly increased maize yield by 10.9%compared with D,and S significantly increased by 15.8% compared with CK(P<0.05).Abundant rainfall during the growth period is another important factor to promote the increase of maize yield.In 2020,biodegradable film mulching combined with straw returning can further improve maize yield on the basis of single film mulching or straw returning,DS will increase by 7.5% on average compared with D,S and CK,respectively(P<0.05),40.2%(P<0.05)and 58.6%(P<0.05),straw returning had obvious effect on yield increase(5)Biodegradable film mulching and straw returning significantly increased the CO2 emission fluxes of maize in the growth period of the two seasons,and the differences between treatments were significant.The average emission fluxes of DS,D and S increased by 55.84%,40.75% and 50.43% compared with CK,respectively(P<0.05).Compared with CK,the average annual N2 O cumulative emission fluxes of DS,D and S were 1.19 kg ha-1,0.9 kg ha-1 and 0.73 kg ha-1,respectively,significantly increased by 52.12%,15.48% and decreased by 6.82%.In 2019 and 2020,CH4 absorption was observed in most of the growth period of each treatment,with an average absorption range of 0.06 to 0.09 kg m-2 h-1 and 0.1-0.14 kg m-2 h-1(6)In 2020,the net income of each treatment shall be D>DS>S>CK,covered with biodegradable membrane,can significantly improve the net benefit of treatment.Straw returning could effectively reduce the global warming potential,and DS had the best effect.The size of NGWP in each treatment was similar in two successive growth seasons.D>CK>S>DS.Under the influence of NGWP and grain yield,the carbon footprint of each treatment during growth period was consistent with that of NGWP,and the carbon footprint of DS was significantly lower than that of other treatments.In conclusion,straw returned with biodegradable film(DS),through the optimization of the soil water thermal environment,has realized the spring maize yield increase and the increase of soil organic carbon content,while promoting the farmland greenhouse gas emissions,but through the soil organic carbon sequestration and higher grain yield,reduce the global warming potential,reduce the carbon footprint,farmland has high environmental benefit and economic benefit,can be replicated in arid and semi-arid rainfed agricultural areas. |
