Agriculture Reference
In-Depth Information
FIGURE 3.7
Multiwattage ballasts for 400-, 600-, or 1000-watt lamps.
(Courtesy of Sunlight Supply, Inc., Vancouver, Washington.)
leaves and plants tending to grow toward the lights. Fewer lights can be
used to cover the same distance while still keeping the correct intensity by
positioning the light closer to the crop canopy without causing burn. Light
movers include a drive motor and a rail on which the light travels, or in the
case of circular movers the light will rotate around the fixed position of the
arms. A linear mover will move the light back and forth on a track. Tracks
may be 2 to 6 feet long. The lights travel about 2 feet per minute, but some
are available in variable speeds from 2 to 4 feet per minute. They usually
have a 0- to 60-second adjustable time delay for pausing the lamp at the
ends of its travel to promote even plant growth from end to end. Prices vary
from $250 to $300 per unit and to more than $500 for more commercial
units that are capable of moving two or three lights side by side as manu-
factured by Gualala Robotics with its LightRail 5.0 system.
Linear movers are best suited for long, narrow growing areas, whereas
circular movers are better for more square growing areas. Revolving
360-degree units may support from one to five lights (Figure 3.8). A three-
arm mover with three lights can cover an area of 10 × 10 feet. They revolve
at 16 revolutions per hour. These units cost from $350 to $450.
Do not be fooled by claims made that light movers allow you to plant
more plants at a higher density than we already discussed. The light mov-
ers help to distribute the light more efficiently over the crop, but they do
not increase the energy given to the plants; that is, fixed by the wattage
and number of lights. However, they can increase production by reduc-
ing mutual shading among leaves of the plants, which may result in more
even growth.
