| In arid and semi-arid regions,realizing the efficient use of water resources is an important way for sustainable agricultural development.Hetao Irrigation District is a super large-scale irrigation district in China.Affected by the water delivery and distribution system,the untimely characteristics of irrigation are outstanding.At the same time,due to limited groundwater resources,it is difficult to apply high-efficiency water-saving irrigation technologies（drip irrigation,sprinkler irrigation,etc.）in irrigation areas.Surface irrigation（border irrigation,furrow irrigation）will be the main method of irrigation in Hetao.Irrigation performance in border fields is an important factor affecting crop yield and water use efficiency.In view of the low irrigation efficiency caused by the large border blocks in the Hetao irrigation area,exploring suitable irrigation technical parameters under changing environments is the key to improving current surface irrigation technology.Studying the characterist ics of water and salt migration in furrow irrigation soil under the mulching film and straw mulching of saline soil in Hetao,and clarifying the change law of furrow irrigation crop yield and water use efficiency,can provide reference for the extension of furrow irrigation cultivation technology in irrigation area.This paper takes the upstream and middle reaches of the Hetao Irrigation District as the main research area.Starting from the actual needs of agricultural production in the irrigation area,experiments on border irrigation and furrow irrigation are carried out to analyze the impact of different irrigation technical elements on irrigation performance.WinSRFR model simulation,numerical calculation and other methods are used.Determine the optimal combination of irrigation technology parameters,and analyze the law of soil water and salt movement under different ridge back straw mulching amounts based on the measured data,and determine the appropriate straw mulching amount.The main findings are as follows:（1）Comparative analysis of the impact of different soil types on the irrigation performance and water production efficiency of the borders of different soil types through typical experiments.When the size of borders is increased from 1 mu to 3 mu,the irrigation time is prolonged and the leakage loss during the flow of water increases,resulting in irrigation efficiency and irrigation uniformity decreases.Although the output slightly increases（1.87%～5.81%）,the water production efficiency decreases by8.49%～21.05%.Combined with the simulation of WinSRFR model,the main technical parameters affecting border irrigation performance,such as border flow rate and irrigation time,were systematically studied,and the irrigation time and border flo w rate required for typical field specifications under different soil types to obtain the optimal irrigation effect were determined.Except for 1 mu of clay loam soil and 3 mu of sandy soil,the irrigation effect cannot be optimal,and the optimal irrigation management parameter combination can be obtained for other working conditions.（2）When the sand border field size（80m×25m）is large,the irrigation performance is poor.Using the WinSRFR model to simulate and analyze the impact of different variable parameters on the irrigation performance,it is found that the irrigation design scheme of"improved field specifications+controlled irrigation time"has significantly improved the irrigation effect compared with typical fields.It is recommended that lar ger sandy soil fields be reduced according to vertical division（80m×12.5m）.At this time,the irrigation efficiency of the field can be increased from 67%～80%to 97%～99%at a larger flow level（q=2.08～2.40L/（m·s））,irrigation uniformity is increased from 0.59 to 0.79 to0.84 to 0.95,and water storage efficiency is reduced from 1.17 to 0.76,which can save more than 20%of irrigation time.Under the condition of medium flow（q=1.60L/（m·s））,it can save 40%of irrigation time while obtaining better irrigation performance,and the water saving effect is significant.（3）Through field experiments,it was found that fertilizers,seeds,and mulching film accounted for a relatively large amount in agricultural production,accounting for more than 70%of the total cost.After the field was reduced,the mechanical cost increased by 0.3 to 4.6 times compared with the control,although the water fee was slightly reduced,but the total cost still increased by 2.72%～9.98%.Using WinSRFR model simulation,numerical calculation and other methods,the optimal single-width flow q=2.81L/（m·s）for fine border irrigation,irrigation time t=21.21min,and border widths are about 10.7～14.2m.It is also recommended that irrigation districts properly issue water-saving subsidies to farmers when promoting new water-saving technologies to increase farmers’enthusiasm.（4）By constructing a mathematical model of agricultural machinery fuel consumption,calculating the fuel consumption of agricultural machinery in different fields,and comparing it with the measured value,the determination coefficient R2 is0.9824,and RMSE is 0.32L,the result is reliable.Considering the efficiency of agricultural machinery,the suitable border length of sandy loam in the irrigation area is reduced from 90-100m to 80-100m,and the flow rate per width can be reduced from2.5-3.5L/（m·s）to 1.5-3.5L/（m·s）,the width is increased from 5.7-8.0m to 5.7-13.3m,which can enlarge the field appropriately.Although the irrigation efficiency and irrigation uniformity were reduced by 2.21%～6.07%and 6.82%～7.08%,respectively,compared with before considering the efficiency of agricultural machinery,there was no significant difference.（5）Through the method of combining model simulation and theoretical analysis,analyze the 3 kinds of irrigation depth control targets（that is,when the water flow just advances to the end of the pass（Zmin>0）,the average infiltration depth in the 1/4 field with the smallest amount of irrigation water infiltration is equal to the required water depth（Zlq=Dreq）,and the minimum irrigation depth is equal to the required water depth（Zmin=Dreq））.It is preliminarily determined that the 100m middle ditch with slope and small flow into the ditch（S0=1‰,Q=1,2L/s and S0=2‰,Q=1L/s）and the zero slope or when the slope is small（S0=0,1‰）The most suitable control target for the 150m long trench is Zmin=Dreq,and Zlq=Dreq is recommended for other working conditions.（6）Film mulching and straw mulching can effectively inhibit the accumulation of salt in furrow irrigation,and the soil salt content of each treatment at the end of growth period was reduced by 42.76%～52.30%compared with the control,with significant differences.When the amount of straw mulching reaches 1.2kg/m2,excessive straw mulching will cause low soil temperature during the sowing period and reduce the emergence of maize,resulting in a slight decrease in maize yield and water use efficiency compared with the mulching treatment,but the difference is not significant（P>0.05）.It is initially suggested to use 0.9～1.2kg/m2 of ridge back straw mulch instead of conventional mulching to reduce the environmental impact caused by mulching. |
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