Study On Characteristics Of Soil Oxygen Distribution And Growth Dynamics Of Fine Roots Of Apple Trees Under Water Storage Pit Irrigation

The water storage pit irrigation method is a water-saving irrigation method suitable for fruit and forest irrigation in the northern hilly areas of China.In recent years,a large amount of researches have been carried out on soil water,fertilizer and heat for water storage pit irrigation,and fruitful results have been obtained.However,there is almost no research on soil fertility factor-gas,and research is urgently needed.The paper uses the combination of field experiment and theoretical analysis to analyze the oxygen distribution characteristics of orchard under different irrigation methods(ground irrigation,water storage pit(40 cm deep),water storage pit(60 cm deep)).The paper also analyzes the effects of soil moisture,soil oxygen and soil temperature on fine root growth dynamics of apple trees.The main conclusions are as follows:(1)The characteristics of soil oxygen distribution in the root zone of orchard under water storage pit irrigation have been studied.The results show that the vertical distribution of soil oxygen is the same under different pit depths.The soil oxygen saturation decreases with the increase of soil depth.The distribution trend can be fitted by exponential function.The radial distribution law is also the same.The farther away from the trunk,the greater the soil oxygen saturation.The soil oxygen high value zone of pit depth 60 cm is larger than the pit depth 40 cm.The former is concentrated at a depth of 0-60 cm,and the latter is concentrated at a depth of 0-40 cm.The pit depth 60 cm is more conducive to improving the soil oxygen content in the root zone of the orchard.(2)The soil oxygen distributions in the root zone of the orchard under the condition of water storage pit irrigation and ground irrigation have been compared.The results show that the vertical distributions of soil oxygen under the two irrigation methods are the same,and the soil oxygen saturation decreases with the increase of soil depth.In the radial direction,there is no obvious law of oxygen distribution in the ground irrigation soil.Compared with the two irrigation methods,the soil oxygen high value zone under the condition of water storage pit irrigation is large,concentrated at a depth of 0-40 cm,and the oxygen high value zone under the ground irrigation condition is small,concentrated at a depth of 0-20 cm.The method of water storage pit irrigation is more conducive to improving the oxygen content of the orchard root zone.(3)The relationship between soil moisture and soil oxygen distribution in orchard has been studied.The results show that,the vertical distribution of soil moisture from 0 to 80 cm is different.The ground irrigation treatment shows that the soil water content increases first and then decreases with the depth of the soil layer,while the water storage pit irrigation treatments show the soil moisture content increases with the depth of the soil layer.Correlation analysis between soil oxygen and soil moisture shows that there is a negative correlation between soil oxygen and soil moisture at each depth,and the highest correlation is found at 20 cm from the surface.(4)The relationship between soil temperature and soil oxygen distribution in orchard has been studied.The results show that the vertical distribution of soil temperature of the water storage pit irrigation and ground irrigation is the same,the soil temperature decreases with the increase of soil depth in June,and the soil temperature increases with the increase of soil depth in September.The soil temperature in August is a transitional type.Correlation analysis between soil oxygen and soil temperature show that there is a negative correlation between the two in the early growth stage of apple trees;in the late growth stage,there is a positive correlation between the two;in the total growth period,the two is negatively correlated.(5)The relationship between soil water,oxygen and temperature in orchard has been studied.The results show that soil moisture and soil temperature have an interactive effect on soil oxygen,and the interaction between the two on soil oxygen is greater than the single impact of any one on soil oxygen.The interaction is most obvious at 20 cm from the surface.(6)The dynamic changes of fine roots of apple trees have been studied.The results show that with the advancement of the growth stage,the growth of fine roots first decrease,then increase rapidly to reach the peak,and then gradually decrease.In general,the growth of fine roots in the ground irrigation treatment at each growth stage is small,concentrated in the surface layer of the soil,and the fine root growth of the water storage pit irrigation is large,concentrated in the medium-deep layer of the soil.(7)The response of fine root dynamics of apple trees to soil moisture-oxygen-temperature is studied.The results show that the growth dynamics of fine roots of apple trees of different treatments are different from the single factor effect of soil moisture,soil oxygen and soil temperature,the two-factor effect and the three-factor effect.In general,the three-factor effect has the greatest impact on the growth of fine roots of apple trees.Compared with ground irrigation,the method of water storage pit irrigation creates good soil moisture-oxygen-temperature condition for medium-deep root,which is beneficial to deep rooting.Then the root system sufficiently absorbs water and nutrient from the middle and deep soil,and promotes the growth and function of root system.