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# 1-35 - BIE 5110/6110 Sprinkle Trickle Irrigation Fall...

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BIE 5110/6110 Sprinkle & Trickle Irrigation Fall Semester 2004 – Final Exam Include units in all results. Indicate any assumptions that you might make. Don’t show more than three significant digits in any of the results. Name__________________________________ 1. (35 pts) A mature citrus orchard will be drip-irrigated (drip emitters) using a single lateral per row of trees in a 132-ha field area. Other information: Tree spacing is 6.0 x 6.0 m. Peak daily ET is U d = 5.1 mm/day. Seasonal water requirement: U = 660 mm. Effective rain, peak-use period: 1.5 mm/day (average, w/ 90% probability) Residual soil water in the spring: assume zero. Soil water holding capacity is 175 mm/m (medium texture). Irrigation water quality: EC w = 0.89 dS/m. Root zone depth is 1.5 m. Shaded area is 78%. Emitter equation: 0.481 q 0.28P = for q in lph; and P in kPa. Nominal emitter flow rate: q a = 3.85 lph. Manufacturer’s emitter coefficient of variation: 0.0487. Average wetted width at 3.85 lph: w = 2.01 m. Outlets per emitter: one. Use an MAD of 20%. What you need to do: 1. Select an appropriate emitter spacing, S e . 2. Determine the number of emitters per tree, N p . 3. Calculate percent wetted area, P w . 4. Calculate maximum net depth to apply per irrigation, d x . 5. Calculate the average peak daily “transpiration” rate, T d . 6. Calculate the maximum irrigation interval, f x . If f x 1 day, use f’ = 1day. 7. Calculate the net depth per irrigation, d n . 8. Select a reasonable target EU value. 9. Determine (EC e ) max . 10. Determine the transmission ratio, T r . 1 of 10

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