Greenhouse Production Systems
Substrate Culture Systems
Flooded Floor System
Flooded floors work on the same principle and with the same equipment as ebb-and-flow benches. The greenhouse floor is poured concrete with raised edges or curbs that allow the floor to be flooded and drained (See Figure 14.9). Fill time is typically five to 10 minutes, and drain time is slightly longer. The depth of the irrigation head and the fill time are linked and depend on the rate that water can be pumped onto the floor. The greater the depth, the longer it takes to drain as well. Containers in the center of the floor have both a longer contact time and a slightly higher head than those at the edge. The floors are pitched from the edge to the center at approximately 0.5 percent slope.
Advantages and Disadvantages
One big advantage with flood floors is the labor, saving possibilities. From rolling shipping carts right out to the where the product is being grown, to portable or stationary conveyor belts, to custom forklift systems for spacing and transportation, the wide-open growing area is perfect for automation and product movement. For seasonal crops, cleared floors can serve double duty as storage and staging areas for shipping. In the flooded floor system, there are no aisles, and all the area can be used for plants with a space efficiency is about 85 to 90 percent.
Flood Floor Designs
“V” Design. There are two basic flood floor designs. The first is known as a traditional flood floor. In this type of flood floor, the concrete is poured and a laser is used to level the floor with a slight grade from the sides towards the center (creating a very shallow “V”). The center is usually 1 to 1 ½ inches (2.5 to 3.75 cm) lower than the high points along the curbs or edges. Water or fertilizer solution is pumped into the flood floor until the depth at the top of the “V” has been achieved. In most cases, the inlets are located in the low center portion of the floor.
"W" Design. A recent innovation is the development of "W" flood floordesign that fills and drains more rapidly. The "W" flood floor design has a wide, shallow "W" shaped profile instead of the "V" shape as in traditional flood floors.
Cascading Design. Another basic type of flood floor is referred to as a cascading flood floor. This type of production surface combines the concept of food floors with troughs, and they are best suited for small containers (less than 6-inch containers). Cascading flood floors are concrete flood floors that are sloped from one side to the other with a drop of approximately ¼ to ? inch (6 to 10 mm) from the high side to the low side. The water or fertilizer solution is pumped into the flood floor on the high side, flows down the slope and is recollected on the low side of the floor.
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