| The Hetao Irrigation District in Inner Mongolia is a typical arid and semi-arid area,with high soil salinization and serious waste of farmland water resources.The problem of soil salinization has become a major issue affecting the sustainable development of agriculture in Hetao irrigation area.Optimizing irrigation measures and agronomic measures is of great significance to the sustainable development of agriculture in the region.As a new type of soil improver,straw biochar has a good improvement effect in improving soil structure,increasing crop yield,increasing water use efficiency,etc.However,biochar has relatively little research on saline soil improvement.Different irrigation conditions have different effects on soil water,heat,salt transport and crop yield.In order to explore the effect of applying biochar on soil water,heat,salt transport and crop yield under different irrigation methods,this article is based on three consecutive years of field positioning experiments,using three different irrigation methods(groundwater drip irrigation,groundwater border irrigation,Yellow River water border irrigation)Coupling with biochar(30 t/hm2)to study the medium-and long-term comprehensive effects of soil water and heat salt transport characteristics,crop growth and water use efficiency,and provide technical reference and guarantee for soil water and salt regulation under different irrigation methods in Hetao irrigation area Local agricultural production and sustainable use of salinized soil.This study mainly draws the following conclusions:1)By comparing the dynamic changes of soil water storage and soil moisture content at different depths under different irrigation methods without biochar,it can be found that applying biochar under the same irrigation method can find that applying biochar under drip irrigation can improve soil storage.Water volume(-6.8-3 mm),the application of biochar under border irrigation has little effect on soil water storage(-4.4-7.7 mm).Through the change of soil water content in the third year after a single application of biochar,it was found that under the same irrigation conditions,the impact of biochar on soil water storage and water content was weakened.2)The coupling of different irrigation conditions and biochar has a significant effect on soil temperature changes.Under the same irrigation conditions,the application of biochar can effectively promote the accumulation of soil temperature.The application of biochar in the Yellow River water border irrigation is most conducive to the accumulation of soil temperature.The average accumulated temperature during each growth period is 140?more than that without biochar treatment.Compared with no biochar treatment,the accumulated temperature in each growing period was 119.80?.3)Different irrigation conditions and biochar coupling have a significant effect on the reduction of soil salinity.In drip irrigation,the salt concentration is mainly concentrated outside the membrane and at 60 cm below the membrane.Under evaporation,the soil moisture moves upward,and the salt moves upward with the water.Finally,the soil salt accumulates in the 30-60 cm soil layer.Under the same irrigation method,the application of biochar has a significant effect on soil salt changes,and the application of biochar to drip irrigation has the best salt suppression effect.Under drip irrigation,the application of biochar in the 0-40cm soil layer reduced the average salt accumulation by 102.7 kg/hm2,and the 0-100cm soil layer reduced the average salt accumulation by 168.0 kg/hm2.In the third year after biochar application,the soil salinity was significantly reduced.The relative desalination rate of biochar applied by drip irrigation reached 13.3%.The relative desalination rates of biochar applied by groundwater and border irrigation of the Yellow River were 5.9%and 3.1%respectively.4)Coupling of drip irrigation and biochar can significantly reduce crop water consumption.Under different irrigation conditions,drip irrigation reduces the average annual water consumption of crops by 28.5mm compared to border irrigation,of which it increased by 39.9mm in 2017.Under the same irrigation conditions,the application of biochar can reduce crop water consumption.The application of biochar in drip irrigation reduces the average annual water consumption of crops by 42.6 mm,and the difference in water consumption of biochar crops in border irrigation is small.Among them,groundwater border irrigation reduces by 29.4 mm;and Yellow River water border irrigation reduces by 22.1 mm.Drip irrigation has the best water saving effect with biochar,and the most significant reduction in crop water consumption.The average annual reduction of different treatments is 37.1mm.In the third growing period,under different irrigation conditions,the effect of applying biochar on crop water consumption was weakened.5)Coupling of drip irrigation and biochar has the best effect on the increase of crop dry matter accumulation and yield.Under different irrigation conditions,drip irrigation significantly increased plant height and dry matter accumulation.Compared with border irrigation,drip irrigation increased plant height and dry matter accumulation by 0.05-0.29 m and 612.3-10164.1 kg/hm2,respectively.Less affected.Compared with border irrigation,the output of drip irrigation strips increased by 1129.6-2434.3 kg/hm2(p<0.05);the water use efficiency increased by 1.9-5.7 kg/m3(p<0.05).Under the same irrigation conditions,the application of biochar significantly increased crop height,stem thickness,leaf area,and dry matter accumulation.The application of biochar to drip irrigation has the most significant increase in plant height and crop dry matter,with an average annual increase of 0.09m and 4105.3 kg/hm2;the application of biochar to the Yellow River water border irrigation has the most significant increase in yield,with an average annual increase of 1252.4 kg/hm2;Charcoal has the largest increase in water use efficiency,with an average annual increase of 4.6 kg/m3(p<0.05). |
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