| Drip irrigation technology is an efficient water-saving irrigation method,with the characteristics of water-saving and fertilizer-saving,etc.Drip irrigation technology has been widely used in order to alleviate the contradiction between supply and demand of agricultural water and to improve the efficiency of water and fertilizer utilization.In recent years,the application of drip irrigation in Yellow River irrigation areas has also become more popular,while the high turbidity of the Yellow River water can easily lead to clogging of drip irrigation drippers.In this study,three kinds of fertilizers were experimented through an indoor short-period intermittent irrigation test method.Three kinds of sediment concentration(1.0,1.5and 2.0 g/L)and three fertilizer concentrations(1%,2% and 3%)were set to study the effects of different fertilizer types and concentrations on sediment output amount,sediment particle size and sediment transport capacity,which provides guidance for drip irrigation of high-concentration source water and fertilizer in the Yellow River irrigation area and for the study on effects of drip irrigation and fertilization in muddy water on clogging law and mechanism of dripper.The main conclusions of this paper are as follows:(1)After applying fertilizer in muddy water,the sediment transport capacity of dripper applying urea reached the largest,followed respectively by compound fertilizer and potassium sulfate.After urea was applied,the average output sediment amount of the dripper was not larger than that with no fertilizer and increased with the rising fertilizer concentration;the distribution range of sediment output increased after application of urea.When potassium sulfate was applied in muddy water,the average output sediment amount of the dripper was larger than that of unfertilized as the sediment content was 1.0 and 1.5 g/L.However,when the sediment concentration was 2.0 g/L,the average output sediment amount of the dripper was comparatively smaller than that of non-fertilizer.(2)There was a significant positive linear correlation between cumulative sediment output and accumulated irrigation volume.The fitted linear slope of the accumulated sediment output and accumulated irrigation volume of the urea treatment was greater than that of the unfertilized treatment.When the sediment concentration was 1.0 and 1.5 g/L,the fitting slope of the potassium sulfate treatment was larger than that of unfertilized application;when the sediment concentration was 2.0 g/L,the fitting linear slope of the potassium sulfate treatment was larger than that without fertilizer;when the sediment concentration was greater than 2.0 g/L,the slope was just in the opposite.There was a significant negative linear correlation between the accumulated sediment output and the average relative flow,and the average relative flow decreases with the rising accumulated sediment output.The reduction rate of the application of urea treatment was slower than that of the non-fertilizer treatment,and the reduction rate of the application of potassium sulfate and compound fertilizer treatment was faster than that of the non-fertilizer treatment.(3)With the increase of irrigation times,the sediments output rate of dripper gradually decreased,and the sediment output rate of drippers was less than 100%.After using urea,the sediment output rate of drippers was larger than that of unfertilized treatments,and it increased with the rising fertilizer concentration.When the sediment concentration was 1.0 and 1.5 g/L,the sediment output rate of potassium sulfate treatment was greater than that of unfertilized treatment.After urea was applied,the degree of declining of sediment output rate was smaller than that of unfertilized treatment with irrigation times increased.The degree of declining of sediment output rate treated with potassium sulphate and compound fertilizers was larger than that from unfertilized treatments with increasing irrigation times.(4)Compared with non-fertilizer,application of urea in muddy water mainly changed the ratio of silt and sand in the output sediment,thereby affecting the sediment transport capacity,increasing the proportion of silt,and decreasing the proportion of sand;applying urea had the greatest impact on the proportion of sand in the output sediment.Applying potassium sulfate and compound fertilizer had the greatest influence on the proportion of clay and sand in the output sediment of the dripper,and had the smallest impact on the ratio of silt and sand.The fractal dimension of the sediment output was positively correlated with the proportion of clay and silt,and was significantly negatively correlated with sand ratio.The fractal dimension of the output sediment was mainly determined by the proportion of clay,and fractal dimensions can be used to characterize the changes in the proportion of sediment particles.(5)After the application of urea,the single output sedimentation capacity and integrated sediment transport capacity of the dripper increased.After potassium sulfate was applied in muddy water and sediment content in muddy water was 1.0 g/L,the integrated sedimentation ability of the drippers after fertilization was greater than that without fertilization.When the sediment concentration was 1.5 and 2.0 g/L,the integrated sediment output capacity with fertilizer was smaller than that without fertilizer.In the comparative study of three kinds of fertilizers,after applying potassium sulfate and compound fertilizer,single sand transport capacity and integrated sediment transport capacity were smaller than that without fertilizer when the irrigation ended. |
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