ADVERTISEMENTS:
This article throws light upon the top four new cropping systems of green house crops. The cropping systems are: 1. NFT System (Nutrient Film Technique System) 2. Floor Ebb and Flow System 3. Trough Culture 4. Rock Wool Culture.
Cropping System # 1. NFT System (Nutrient Film Technique System):
It is a specialized form of hydroponics. In this system, the growing of plants in a system where thin film (Few millimeters) of nutrient solution is circulated through a trough that contains the plant roots. This system was outlined in detail by Cooper (1979). This system has a channel laid out on 1% slope. The channel must be level across its width to ensure that the whole floor will be covered with nutrient solution.
Such channels may be situated on raised platforms. The width of channel is 23 cm and depth is 5 cm. It may be from concrete, metal or wood. The channel should be water tight. Channels lined with a plastic film sufficiently large to cover the top of channel including propagating blocks. This film should be of 5 mil thickness which will not adhere with the roots and will force nutrient solution to move along with the slope.
ADVERTISEMENTS:
Covering of channel will check the evaporation, restrict light entry to prevent algal growth and help in controlling room temperature. Nutrient solution is circulated in a closed recirculating system from tank. The flow rate of solution should be sufficient to maintain a film of 3 mm thickness. Cooper used following nutrient solution successfully for more than 50 of species.
Plants for NFT system are propagated in containers such as blocks of rock wool, foam cubes, netlike pots containing soil less media. The main advantages of this system are: It eliminates the labour of sterilization. It has tremendous potential of water and nutrient conservation. Whole system is automated so it saves labour.
Cropping System # 2. Floor Ebb and Flow System:
Potted and bedding plants are grown on the floors. The floor is raised around and drained in the center so that is can be flooded and drained in the fashion as an ebb and flow bench system. The advantage of floor recirculating system is considerable cheaper, labour cost and expensive benches are not needed.
ADVERTISEMENTS:
However, floor must be leveled with laser beam. Some difficulty may felt about labour as they have to bend during the cultural operation.
Cropping System # 3. Trough Culture:
It is modification of ebb and flow culture. In this system, single rows of plants are grown in water tight trough. Troughs are sloped from one end to another with a decline of 2.5 cm per 10 m. Nutrient solution is pumped from high end where it slowly trickled down by gravity to supply to each pot on the way. At the low end solution is collected through connected gutters and recalculated again and again.
Cropping System # 4. Rock Wool Culture:
In this system rock wool slabs are covered with polythene used on a floor. Each slab is used for a single plant and is placed on top of slabs at the desired spacing for the crop involved. Root penetrates into the slabs below the cubes in two or four days. Each slab is connected with water tube. Nutrient solution is applied with each watering. Crops can require 3-10 applications per day.
This application will vary with plant size and weather conditions. This method has certain advantages as it does not need pasteurization. Rock wool is an excellent inert substrate for open system. Rock wool is light in weight and self-contained. The light weight permits growth of crop on benches. This reduces the cost of production as there is reduction in average growing space.
