looks like drip irrigation in bag culture. the water gets absorbed by the plants roots and the growing media.

cheaper than a lot of the other hydro setups on the same large scale

Hi Fred42,

It looks like a bag culture system. It is similar to sawdust culture where a bag of sawdust is laid on its side and one side slit for planting. A feed tube is inserted and nutrient metered in. It is a total loss system, i.e., no nutrient is recovered.

The bags are almost certainly woven, and can leak, but as the nutrient is metered in, there would not be much leakage as the feed rate would be tightly governed. The rice hulls would not hold much water, but the coco-peat would. It is possible that the feed rate is such that excess nutrient trying to leave the bag simply evaporates when it reaches the outside of the bag.

Cheers,
Jimr007.

Thanks Jim.
Incidently,I have noticed in garden centers there that potted plants are in a mixture of soil and rice husk..If it doesnt retain water,I wonder what its purpose is?
One more question..I know that in these tropical countries it is very hard to grow things like lettuce,strawberries by conventional means ect except at high altitude where it is cooler..I was just wondering why this is? If it has anything to do with the ground temperature would a hydroponics system solve this problem because of the roots only having contact with cold water?
Thanks again.

lettuce is hard to grow in heat because it stimulates seed production also the increasing day length in the south where i live stimulates the bolting action

most strawberries die when temps increase as well but there are a few varieties that can handle higher temps.

most plants do best in a hydroponic solution temp at about 60-65F but if you still have high air temps you arent going to grow too many strawberries or lettuces

rice husks are there just to have a media to grow on. and so the media doesnt become too saturated promoting root rot

if you want to play with the bag culture technique, you can get bags made from panda film, and bulk perlite or tiny rockwool nuggets from carefreegarden.com

its a run to waste system so you'll need a very large reservoir.

i find watering short but often uses less water than watering long but not as often. my tomatoes outside in rockwool running to waste get 45 seconds every 45 minutes when the sun is pounding down on them. otherwise its 55 seconds every 4 hours. using 4gph drip stakes.

i would start with a recirculating system so you can use a tds/ec meter to learn what the plant is doing. if the reading goes up, the plant is being overfertilized, if the reading goes down, the plant wants more fertilizer. in a system where the nutrient runs to waste, you cant really measure the runoff very easily to see what the plant is doing. im trying to say it helps to have a few grows under your belt before going with this method. there are plenty of recirculating drip systems out there. i learned on an american agritech jetstream system.