Distribution Of Soil Water And Heat On Subsurface Irrigation With Stalk Composite Pipe

Stalk subsurface irrigation is a new technology of subsurface irrigation using the developed stalk composite pipe.In order to clarify the soil moisture and temperature distribution of the stalk subsurface irrigation technology,a field experiment was carried out,and the location and observation of different positions from the stalk composite pipe during the growth period of winter wheat were carried out.The change process of soil moisture,soil temperature and air temperature was analyzed,and the water movement and temperature changes of the soil irrigated with stalk in different periods were analyzed.The main conclusions reached are as follows:（1）Under the conditions of a working pressure of 0.5 m and a buried pipe length of 80 m,the water flow of straw subsurface irrigation can reach the end of the straw-pipe composite pipe within 1 h of water supply,and the stalk-pipe composite pipe can be used as a field capillary for subsurface irrigation.During the irrigation process,the soil moisture moved outwards with the stalk composite pipe as the center,in an ellipse shape with a narrow upper and a wide lower bottom;when the composite burial depth of the stalk pipe was 0.2 m,the main influence range of irrigation water was 0.5 m below the surface and the distance from the stalk composite pipe.Within a horizontal distance of 0.3 m,the soil moisture content in this area was negatively correlated with the distance of the stalk composite pipe,and the difference reached a significant level;6-24 h after irrigation,the distribution of soil moisture on the profile reached a relatively stable state,and the amount of irrigation The larger the value and the longer the irrigation time,the longer it takes for the soil moisture content to stabilize.（2）Soil temperature is mainly affected by air temperature,irrigation amount and irrigation water temperature.Under the conditions of stalk subsurface irrigation,the effect of air temperature on soil temperature decreased with the increase of depth,and its influence range was about 0.3 m below the surface;Irrigation volume has obvious influence on soil temperature distribution,while irrigation water temperature mainly affects the average soil temperature after irrigation;in the horizontal direction,the change of soil temperature decreases with the increase of depth at the same position from the stalk composite pipe.（3）When the stalk composite pipe is used for subsurface irrigation,the amount of water in winter irrigation is between 150 and 250 m³·hm^-2,which can meet the water demand of winter wheat without causing a significant decrease in soil temperature;the amount of water in spring irrigation is about 250 m³·hm^-2,which can create better soil water and heat conditions for the growth of winter wheat.（4）Under the experimental conditions,the relationship between soil temperature and soil moisture content varies with seasons.There was a significant quadratic curve relationship between the two in winter（R²=0.785）,and a significant linear relationship between the two in spring（R²=0.785）,and soil water content inhibited soil temperature changes within a certain range.The research results preliminarily show that the stalk composite pipe subsurface irrigation is a feasible irrigation technology,which can achieve the same effect as the subsurface drip irrigation in the production of winter wheat.Limited by the experimental conditions（field test,no rainproof facilities）,only three irrigation experiments were carried out during the growth period of winter wheat,and no irrigation was carried out during the subsequent growth of summer maize due to the influence of rainy weather.Therefore,whether the straw can be used for subsurface irrigation during the growth period of summer maize,and whether the stalk composite pipe can be used for field drainage when there is too much water in the field,still needs to be further studied.During the experiment,it was also found that the decomposition of the stalk composite pipe had a certain influence on the water and heat distribution of the stalk subsurface irrigation technology.However,due to the limitation of time,the influence of the decomposition of the stalk composite pipe on the soil water and heat distribution was not discussed in detail.analyze.The above conclusions have certain reference value for the application and promotion of stalk composite pipe subsurface irrigation technology.The stalk subsurface irrigation technology is still in its infancy,and there are still many subjects that need to be tested and explored,and the related research needs to be further deepened and refined.