Irrigation Water Management Training Irrigation Water Requirements for

Irrigation Water Management Training Irrigation Water Requirements for Planning

Kaldi the Goat Herder • c. 850 A. D.

Write down your answers • Assume 2. 0 inch/foot AWHC and a 12” spate irrigation • Q: After 2 weeks, what is the available soil water in the top foot? In the next 9 feet?

Evaporation from Wet Soil Surfaces Wet soil excel chart here

Evaporation from Wet Soil Surfaces Method Rain Above canopy sprinklers Furrow Irrigation Large application depth Small application depth Every other row irrigated Trickle Irrigation Fw 1. 0 0. 5 0. 25

Write down your answers • What can the farmer do to get a crop?

Irrigation Water Requirements • • Monthly and Seasonal Water Use Peak ET Leaching Requirement Other Beneficial Uses

Look at Willamette Valley IWR Sheet • Q: What column (e. g. 5 out of 10 years) do you use for planning? • Q: What information do you still need?

Look at Willamette Valley IWR Sheet • Q: Look at June for cherries and field corn. What can you say about the crop coefficient for each?

Peak ET • What was the highest one day ET for Baker Valley, OR in 2004? • 2 day? • 7 day? • Is this data valid for your crop (field corn, for example)?

Define Irrigation Efficiency • Write down your definition of irrigation efficiency.

Define Irrigation Efficiency • Define your boundaries • Keywords – Percent – Irrigation Water – Applied – Beneficial Use

Assume no rain • • 30 inch ET requirement Scheduling is Good Farmer applies 30 inches What is the irrigation efficiency?

How are the Irrigation Water Requirements determined? • Irrigation Water Requirements (NRCS) – Penman-Monteith – Radiation – Temperature – Evaporation Pan

It depends on the crop • Crop Coefficient

It depends on the weather • Reference ET

To a small extent, it depends on the type of irrigation system • How much of the soil surface is wetted, and how often.

It depends on the soil type • How much water can evaporate from the soil surface

It depends on the rainfall • How much of the rainfall is effective.

True Water Conservation • Less ET – Land Fallowing – Shift Crops – Less Evaporation – Shorter Growing Season (new varieties)