1. Design of Irrigation Systems by László Ormos

2. Measurement Apparent specific gravity (bulk density) S
where mM means the weight of given volume of dry soil, air space
included, and VM is the volume of soil sample.
Real specific gravity S
where mM means the weight of given volume of dry soil, occupied by
the solid particles, and VM is the volume of soil sample.

3. Measurement
Porosity P is the ratio of the volume of voids (air and water-filled space)
to the total volume of soil plus water and air.
Moisturisation FS
where mD means the weight of dry soil sample.

4. Measurement Field capacity FC
Home-made measuring of field capacity is running as
follows:
Select 1-2m2 surface of field
Make a heavy irrigation on soil
Waiting for draining (sandy soil: 24 hrs, clay: 48hrs)
Take samples from the soil
Measure the weight of moisturized sample
Dry it in an oven at 105°C
Measure the weight of dry soil
Compute the water content FS
Repeat actions 2-8 till FS is changing
When FS is not changing then its value is the field capacity FS t FC

5. Measurement Simple method for measuring FC of sandy soil
Fill the sample of sandy soil into a can
Drip 5ml of water on the soil surface
After a minute, spill the soil from the can
and take the moisturized ball from the soil out
4. Clean the surface of soil ball from dry specks
5. Detremine the water content of soil ball
described previously (4.-7.)

6. Measurement Permanent wilting point PW (by sunflower method)
Seem sunflower seeds in a pot
Irrigate it to reach field capacity
When the plant has three pairs of leaves
stop the irrigation
4. When the plant is wilted, the soil moisture
content is the wilting point

7. Evapotranspiration
(evaporation + transpiration)
evaporation is running during night and day,
transpiration of most crops is in daytime, only.
Integrated effect of radiation, wind, temperature
and humidity.

8. Pan evaporation method
Class A evaporation pan
 46.5”(1210mm)
10”(~255mm)
6”(~150mm)
2”(~50mm)
3”(~75mm)
Galvanized iron plate
thickness 0.8mm
<2”(~50mm)

9. Pan evaporation method
2. Class B evaporation pan
36”(~920mm)
18”(~460mm)
2”(~50mm)
Galvanized iron plate
thickness 0.8mm

10. Pan evaporation method
Set of pan Case A
wind
50m, or more
varies
dry surface green crop
pan

11. Pan evaporation method
Set of pan Case B
wind
pan
50m, or more
varies
green crop dry surface

12. Pan evaporation method
Reference crop evapotranspiration
where
Epan means the evaporation in mm/day and represents the mean daily value of the period considered,
Kp is the pan coefficient.

13. Pan evaporation method
Crop coefficient
To account for the effect of the crop characteristics on crop water requirements, crop coefficients Kc are presented to relate ET0 to crop evapotranspiration.
1 initial stage (groundcover<10%)
2 crop development stage (ground cover ~70-80%)
3 mid-season stage (full ground cover)
4 late season stage
Maturity
Harvest Kc t
Planting date

14. References
Azenkot, A.(1998):”Design Irrigation System”. Ministry of Agricul-
ture Extension Service (Irrigation Field service), MASHAV Israel
Dr. Avidan, A.(1995):”Soil-Water-Plant Relationship”. Ministry of
Agriculture Extension Service (Irrigation Field service), CINADCO,
Ministry of Foreign Affairs, MASHAV, Israel
Sapir, E.-Dr. E. Yagev (1995):”Drip Irrigation”. Ministry of Agricul-
ture and Rural Development, CINADCO, Ministry of Foreign Affairs,
MASHAV, Israel
Sapir, E.-Dr. E. Yagev (2001):”Sprinkler Irrigation”. Ministry of -
culture and Rural Development, CINADCO,Ministry of Foreign
Affairs, MASHAV, Israel
Eng. Nathan, R. (2002):”Fertilization Combined with Irrigation (Fertigation)”. Ministry of Agriculture and Rural Development, CINADCO,Ministry of Foreign Affairs, MASHAV, Israel