| Object: In order to ensure the sustainable development of agricultural ecology and economy in Oasis Irrigation area,drip irrigation technology under mulch should continue to play an effective role in reducing the harm of plastic film residue to farmland from the source.In this study,the effects of three types of degradable plastic film on the salt temperature of one-dimensional soil evaporation effluent and its degradability in arid area were studied,and the mechanism of the effect of degradable plastic film mulching on farmland irrigation was explored.The theoretical basis for degradable plastic film mulching drip irrigation was provided,and the types of degradable plastic film suitable for the application of Oasis Irrigation Area in arid area were screened,so as to further promote the application of degradable plastic film.The purpose of this study is to provide references for solving the problem of residual membrane pollution.Methods: This study was conducted in the Key Laboratory of Modern Water-saving Irrigation Corps and the Water-saving Irrigation Test Station of Shihezi University from August to October 2017.The biodegradable film used in the test is complete biodegradable film(PBAT)and biodegradable film(starch),which are sold in Xinjiang market.The test was carried out for 3 rounds,5 treatments per round,3 replicates,and a total of 45 treatments.The soil moisture infiltration was first carried out and then the evaporation test was carried out.In the evaporation test,the distance between the bottom of the enhanced light source and the topsoil of the soil column was respectively 20,40,60 cm,day and night illumination.Results:(1)The water and salt transport of different mulching treatments were analyzed,and the changes of soil moisture and salinity were interacted.The effect of different degradable film mulching on soil water and salt transport varies with the different light intensity.The effect of film mulching on soil moisture retention is more obvious,and the effect of BD2 treatment in three kinds of degradable film is better.With the decrease of light intensity,the light source heat received by each soil column decreases,and the change of salinity in soil decreases.The three degradable plastic mulches and ordinary plastic mulches have less regularity on soil salinity,and BD2 has better salt inhibition effect.The soil water content of BD1,BD2 and BD3 treated with biodegradable film in 0-20 cm soil layer was not significantly different from that of P E treated group(P > 0.05).In the treatments of BD1,BD2 and BD3,the changes of soil salinity after redistribution were similar,but the regularity of soil salinity under BD2 treatment was more obvious than that under PE treatment(P < 0.05).(2)Film mulching can effectively increase and maintain soil temperature,but different film mulching has different effects.When the light intensity is the same,soil temperature gradually increases with time,and gradually decreases when it reaches the maximum.The soil temperature of degradable membrane treatment is similar to that of PE treatment,which can effectively increase the temperature of deep soil.(3)The evaporation intensity of CK group was higher than that of other treatments under constant indoor evaporation environment,soil quality and infiltration form.The water retention of BD2 treatment was better than that of the other two treatments under high and medium light intensities.Under low light intensity,the water retention of BD1 treatment was better than that of the other two degradable film treatments.Over time,the cumulative evaporation of different treatments showed significant regularity.The cumulative evaporation of CK group increased in a positive proportion function,while that of mulched soil increased exponentially with time.Under high light intensity,the cumulative evaporation of each treatment increased in a positive proportion function with time,and under medium light intensity,the cumulative evaporation of film-mulched soil(BD)increased in a positive proportion function with time.1.The cumulative evaporation of BD2,BD3 and PE increased exponentially with time.(4)Three kinds of degradable plastic films studied in this experiment did not reach the ideal degradable level under the condition of continuous light radiation.From the three-round test results,it can be seen that with the decrease of light intensity,the degradation degree of the three biodegradable films decreases in turn,and the time for the earliest cracks to appear is delayed,and the number of cracks is also greatly reduced.Conclusion: Degradable plastic film mulching has a significant effect on soil water,salt and temperature,and light intensity also has an impact on its degradation degree.Under the experimental conditions,considering that all three types of degradable plastic film can keep water,keep heat and inhibit salinity,considering the degradability of degradable plastic film and the influence mechanism of degradable plastic film mulching on farmland irrigation,B-type fully biodegradable film(PBAT,the main component,0.010 mm thick,60 days design degradation induction period)has more promotional value. |
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