Study On The Rule Of Soil Water Migration Under Different Irrigation Patterns

The study of soil water movement law under different irrigation conditions is the premise of agricultural irrigation design and has practical guiding significance for accurate management of irrigation.In this paper,the experimental field that has been cultivated for many years is selected,and the experimental area is divided into three zones.On the premise of not changing the original soil environment,relevant experiments are carried out by three irrigation methods,including furrow irrigation,drip irrigation and small pipe discharge.The effects of irrigation time,flow rate per unit time,transition of wetting front,average water content,water content distribution of wetting body and water redistribution after irrigation were studied.Soil moisture content was measured using a soil drying method and portable soil moisture meter.T he purpose of t his study is to explore the characteristics of soil water transport in different irrigation methods,so as to carry out agricultural production in the most efficient and water-saving irrigation methods according to different conditions.Through the research in this paper,the migration law of soil moisture under different irrigation methods can be obtained,which provides necessary theoretical basis and scientific support for promoting the integration of water-saving irrigation and fertilizer and water in large areas in China.The following conclusions can be drawn from the study:In the furrow irrigation mode,the mean water content of soil increased first and then decreased with the extension of irrigation time.When the soil depth was 20 cm,the mean water content of soil increased gradually with the extension of irrigation time.After more than 2 hours irrigation,the increase of mean water content of soil slowed down,and the curve gradually tended to be stable.When the soil depth is 40 cm and 60 l cm,with the extension of the irrigation time,the flow 4 L and 20 L have the same trend of change.The mean water content of soil increases first and then decreases then,and the change trend of the mean water content of the soil of the flow 8 L increases first and then decreases.Under the drip irrigation mode,with the extension of irrigation time,the irrigation amount 2 L,4 L,5 L,6 L and 10 L have the same trend of change.The mean water content of the soil increases first and then decreases.When the soil depth is 20 cm,40 cm,60 cm,with the extension of the irrigation time,the irrigation amount 2 L,4 L,6 L,8 L,etc.In the same trend,soil mean water content increased first and then decreased,and finally stabilized.In the tubular outflow mode,the shape of the wetting body is similar to that of the ellipse.The distance of the wetting front running at each location depends on the water discharge of a single tubule.In a small pipe flow,both horizontal and vertical direction,the soil moisture content value will be increased with the increase of infiltration distance reduced,the closer distance pipe head part,the higher water content,at the end of the irrigation,soil moisture did not stop the migration,but with the advancement of time,present state of vertical and horizontal distribution.Under different time consuming irrigation conditions,the change of water content in horizontal and vertical soil is basically the same.On the same horizontal section,the greater the amount of irrigation,the farther horizontal distance of the same water content is reached;the greater amount of water in the vertical section,the fart her vertical distance of the same water content reaches,the greater irrigation amount,the greater wetting distance between the horizontal and vertical directions.In the actual implementation process,different flow pipe heads can be replaced according to the requirements.The HYDRUS model is used to simulate the distribution of water and salt in soil profile and the temporal and spatial variation of soil water and salt in different irrigation modes.The results show that the model can better simulate the distribution of water and salt in the soil and the trend of change with time.The model has a better simulation degree and can be used to simulate the water and salt migration rules in the irrigation area.Different irrigation patterns showed that soil water content of drip irrigation treatments was generally higher than that of double furrow irrigation and furrow irrigation.