Study on the effect of dry seeding and wet emergence on the distribution of water and salt in cotton field and the emergence rate of cotton under the control of drip irrigation in winter
[Objective]To find a more reasonable irrigation system in the dry cotton field area.[Meth-ods]Field experiments were carried out to study and analyze the dynamics of soil water,heat and salt and the emergence of cotton seedlings after drip irrigation in winter under different irrigation quotas and on the basis of different treatments in the next year.With the flood irrigation quota of 2,250 m3/hm2 as the control(CK),four gradient irrigation quotas were designed under the two irrigation modes of drip irrigation(D)and drip irri-gation under the control of dry seeding and wet discharge(DG),4 drip irrigation quotais 600,900,1,200,1,500 m3/hm2(D1,D2,D3,D4);Under the control of drip irrigation in winter,two irrigation quotas of dry seeding(D1G1,D2G2,D3G3,D4G4;The Errigation quota of G1,G2,G3 and G4 is 225(45+180)m3/hm2)and wet production were 0 and 225(45+180)m3/hm2,a total of 9 treatments.[Results]The results showed that dry-sowing and wet-out could alleviate the sudden change of temperature and soil surface temperature in early spring,and the canal water in early spring would reduce the soil surface temperature by 1-2℃.The dry-sowing and wet-out had a significant impact on the temperature of 10 and 20 cm soil layers.Compared with CK treatment,the temperature of 10-20 cm soil layer after dry-sowing and wet-out treatment increased more gently.Compared with flood irrigation,drip irrigation was more uniform in water infiltration.The larger the irrigation quota of drip irrigation in winter,the more stable the soil temperature would be,the higher the average soil surface moisture content was,and the higher the surface moisture content would be after dry see-ding and wetting.After 10 days of treatment,the volume water content of the surface layer with the irrigation quota of D4G4(1,500+225)m3/hm2 was still higher than that of other treatments.The average water content of the surface layer with the total irrigation amount of D3G3(1,200+225)m3/hm2 was higher than that of the CK treatment,and the total irrigation amount was 825 m3/hm2 less than that of the CK treatment.After dry-sowing and wet-out,the salt leaching effect of the narrow row surface layer was significant.The water infiltra-tion and salt migration areas were concentrated in the 0-30 cm soil layer,and the root system of cotton was mainly distributed in the 0-30 cm soil layer at the germination stage.The larger the winter irrigation quota of drip irrigation,the more obvious the vertical leaching and movement of salt on the soil surface,and the more uniform the soil moisture content,the more likely the salt return phenomenon would be likely to occur.Adding dry seeding and wetting could timely supplement the moisture and suppress the salt return phenomenon.[Conclusion]The seedling emergence rate and seedling preservation rate of drip irrigation winter irrigation plus dry seeding are higher than that of drip irrigation winter irrigation only.The seedling emergence rate and seedling preservation rate of irrigation quota of D3G3(1,200+225)m3/hm2 are higher than that of ordinary flood irrigation.
cottondrip irrigation under filmwinter irrigationirrigation quotadry sowing and wet out
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