Germination; Cooling - Netafim SPINNET Handbook

MICRO-SPRINKLER/EMITTER SELECTION
Strip coverage
There are individual
cases, especially when
the crop is grown in
a tunnel or when the
grower wants to divide
one greenhouse span
into two separate
irrigation strips. In
such cases, only one
distribution pipe is
placed above the crop
and is not "assisted" by
micro-sprinklers on an
adjacent distribution
pipe.
For this purpose,
Netafim™ has developed
a dedicated solution:
the SpinNet™ SD (shoulder distribution) micro-sprinkler (see
excellent distribution uniformity with a very high wetting accuracy (i.e. a very high percentage of the water
actually falls within the strip under irrigation), thus increasing water use efficiency.

Germination

Germination is the process in which a seed is planted shallowly (only a few millimeters deep) and the
substrate (soil, substrate or a mix of both) is irrigated so that the seed germinates and becomes a young
plant.
For germination the irrigation must:
• Be very gentle, so that the water droplets will not move small clods of the soil/substrate and leave the
seed exposed, thereby possibly inhibiting proper germination.
• Provide perfect distribution uniformity. Germination is usually carried out on tables/trays divided into
individual cells (the water cannot pass through the boundary between substrate zones). Thus, although
very gentle, the water droplets must be able to provide perfect distribution uniformity.
For this purpose, Netafim™ proposes the VibroNet™ bridgeless micro emitter with vibrating action (see
page 29).

Cooling

Evaporative cooling (i.e. without contact between the water and the plants): a volume of air is cooled
by spraying very small droplets of water into the air. These droplets evaporate (thanks to the physical
attributes of condition equalization of objects when contacting each other). The droplets are at 100%
relative humidity (saturation) and the air inside the structure is at a lower relative humidity (the lower the
relative humidity of the air inside the structure, the more efficient the cooling action). The droplets turn
from liquid to gas (evaporation). Here another physical property enters in action: For every gram of water
evaporating, 560 calories are consumed from the air, as a result the air is cooled (The smaller the droplets,
the more efficient the evaporation resulting in a better cooling action).
For this purpose, Netafim™ proposes the CoolNet Pro™ super-fine mister (see
page 23) that allows farmers to achieve
UPSIDE-DOWN MICRO-EMITTERS HANDBOOK 7
page 31).