Summary of research project: |
Objective and technical fields:
To select effective irrigation methods through rationalization of irrigation technique’s elements. Determination of the optimal parameters of furrow irrigation elements, control of soil’s water regime as well as beneficial water use in a field.
Scientific and technical approach:
To carry out established irrigation schedule, provide high quality of watering, reduce water losses from releases and percolation, determine parameters of furrow irrigation elements. Development of recommendations on a value of elements of furrow irrigation in the Arys-Turkestan canal’s command zone.
Environment characteristics:
Climate is sharply continental. Average annual air temperature is 11,8-12,1oC, in July - +26,3oC. Duration of a warm period (t >10oC) varies from 175 to 190 days. Total sum of positive temperatures (more than 10oC) varies from 4350 to 4400. Average annual precipitation is 160-180 mm. Evaporativity is 1100-1300 mm. Coefficient of moistening is 0,08-0,10. The state farm is located in a mountain adjacent plain of the southern-west slope of Karatou mountain range. Relief is slightly corrugated with 0,003-0,005 slope. Slope of the pilot plot is 0,0035. Diapason of the plot level deviations from a plane with middle slope is +3 cm. Lithology: up to depth of 15 m loam, below - gravel and pebble deposits (10-15 m); PC is 0,3-0,5 m/day. Under conditions of poor natural drainability ground waters level is 2,5-3,5 m; salinity of ground waters is 6-8 g/l. Type of ground waters salinity is chloride-sulphate and sulphate-chloride. There are light gray and heavy loamy soils. Coefficient of absorption is 9-12 mm/minute. Up to depth of 0,5-0,7 m soils are non-salinized, below there are 0,8-1,5% salinized by solid residue. Specific mass of 1 m layer is 2,73 g/cm3, volume mass is 1,44 g/cm3; minimum moisture capacity is 2,17%. Content of soil particles more than 0,01 mm in diameter is 47,12%, physical clay - 52,88%. The state farm was established in 1972. Irrigated area is 5000 ha (gross), 4000 ha (net), land use efficiency is 0,8. Orientation of the farm is cotton-growing. Water supply is done by ditches. Length of canals is 200 km. Head intake is 4,8-5,0 m3/sec. Length of drainage network is 40-45 m/ha.
Parameters of Pilot Projects and Technical Solutions:
The pilot plot is located in a field, the total area of which is 40 ha. Slope is 0,0035. Diapason of the plot levels deviations from a plane with middle slope is +3 cm. Cultivated crop is maize. Water supply of the pilot plot from ditches is done by temporary irrigation network. Water is distributed among furrows from irrigation metallic shields with triangular cut. Depth of furrows is 0,18-0,2 m; length of furrows is 250 m, quantity of furrows irrigated simultaneously is 27; width of a front of one watering is 19,0 m.
Methodology:
Field research for studying the elements of furrow irrigation technique. There were studies of three following alternatives of water discharges in the head of furrows: 1) q1 = 0,25 l/sec (control); 2) q2 = 0,5 l/sec; 3) q3 = 0,75 l/sec. Each alternative was divided into 9 furrows, heads of which were reinforced with metallic watering shields. Discharge in control points and in the end of furrows (for releases) were measured by triangular Tompson weirs. In order to assess experiment results the following indicators were considered: uniformity of soil moistening within the irrigated furrow, value of water losses from releases and percolation, efficiency of irrigation technique.
Results:
Studies (1963-1966) of the elements of furrow irrigation were conducted on maize crops. Distance between rows was 0,7 m. Moisture of soil under maize was more than 70% normal moisture. 5-6 waterings with irrigation norm (net) of 3900-4600 m3/ha were done to keep this moisture level. First watering was done during the phase of 7-8 leaves. There were 2-3 waterings from the period of young-panicle formation till the milk stage of maize grain maturity and 1-2 waterings during the milk stage of maturity and milk-wax one. Root zone of maize till the phase of young-panicle formation was spread mainly in 0-70 cm. During the milk stage of maturity 90% of roots were expanded to 0,90 cm. Irrigation depth at the beginning of growing period was 650 m3/ha, in the middle and in the end of growing period - 850 m3/ha. In 1st alternative water supply during growing period was 6230 m3/ha, in 2nd one - on 970 m3/ha less and in 3rd one - on 445 m3/ha less than in control alternative. Amount of releases and percolation accounted for: 1st - 1308 and 847 m3/ha, 2nd - 1300 and 760 m3/ha, 3rd - 300 and 347 m3/ha respectively. Total water discharge in control alternative was 8020 m3/ha, in 2nd one - 7100 m3/ha, 3rd one - 7600 m3/ha. Total duration of water supply for one watering at q1 = 0,25 l/sec was 25,3 hours, at q2 = 0,5 l/sec - 10,8 hours, at q3 = 0,75 l/sec - 7,8 hours. Duration of the flow running up to the end of furrow at q1 = 0,25 l/sec was 10,1 hours, at q2 = 0,5 l/sec - 4,3 hours, at q3 = 0,75 l/sec - 3,7 hours. The norm of water achieved the end of furrow was 519, 442 and 570 m3/ha respectively. Field water distribution efficiency within the watering front was 0,82. Coefficient of moistening uniformity within the furrow in 2nd alternative was 0,73. Efficiency of irrigation technique in this alternative (EIT= 0,77) as well as in 3rd one (EIT=0,70) is higher than in control (EIT=0,65). Achieved irrigation water saving as compared with 0,25 l/sec flow (control) accounted for 97 m.
The main output of the study is determination of the rational values of furrow irrigation’s elements for middle by field slope and water permeability soils. They are the following: lfur = 250 m; qfur = 0,5 l/sec; t1 = 4,3 hours; t2 = 6,5 hours; t tot = 10,8 hours. These values provide irrigation water saving on 19% and maize yield at 5,3 t/ha.
|
