Netafim SPINNET Handbook page 13

MICRO-SPRINKLER/EMITTER SELECTION
Scheduling Coefficient (SC)
The Scheduling Coefficient is a run-time multiplier. It represents the time needed to over-irrigate to achieve
the average application rate of the entire area in the driest part of the irrigated area.
SC = overall average net application / average net application in the driest parts of the irrigated area
Advantage of the SC method:
SC measurement takes into account the driest area (the part that receives the least water) while ensuring
that the entire area is irrigated with at least the minimum required quantity, according to the crop value.
NOTE
In protected crop applications, it is customary to consider 5% of the entire surveyed area as the
driest area..
NOTE
The SC method is applicable solely for testing purposes, to validate the %CU and %DU methods and
less recommended for irrigation planning.
A perfectly uniform application is represented by an SC of 1.0.
A less uniform application is represented by a higher SC value:
For micro-sprinkler/emitter irrigation of protected crops:
Up to 1.0 Excellent uniformity
1.1 - 1.2 Very good uniformity
1.3 Good uniformity
Higher than 1.3 Acceptable for certain low-value crops only
Calculating SC
1. Gather the water levels previously collected in each gauge or can (mm) [a].
2. Sum all the numbers in column [a].
3. The lowest 5% of the numbers in column [a] are summed up [only 1 number in this example].
4. The sum of all the numbers in the column [a] is divided by the number of gauges or cans placed. This
provides the average net application of the entire surveyed area [b].
5. The sum of the lowest 5% of the numbers in column [a] is divided by 5% of the number of gauges
or cans placed. This provides the average net application of the 5% lowest numbers in the surveyed
area [c].
6. The sum of all the numbers in column [a] is divided by the sum of the lowest 5% of the numbers in
column [a]. This provides the SC value [d].
UPSIDE-DOWN MICRO-EMITTERS HANDBOOK 13