Far from Home

     For the last week I have been in New Brunswick New Jersey, attending the Rutgers turf grass management course, so I am improving my plant knowledge, but I am away from my plants at home.  Before I left, however, I did implement measures to increase my plants' chances of survival.  The DWC units should be fine because the roots are constantly submerged in nutrient solution, but I increased the volume of water in the tanks by a gallon, so there should be very little chance that all the water will be lost due to evaporation or transpiration.  I also mixed the solution about 50 ppm stronger than the previous batch of solution so that the plants will have plenty of food while I'm gone.  I also raised the lights a few inches to make sure that the plants won't touch the bulbs if they get too tall.
    
     As for the germination tray, I bought some materials and set up an irrigation system.  I also set up an additional bin for root vegetables, which I seeded the day before I left.  The germination tray is now a flood and drain system.  In my flood and drain system, the tray is set up on an angle with a 1/4" drain on the down hill side that runs back into the reservoir on the floor.  The theory is that nutrient solution is pumped into the tray faster than the drain can get rid of it.  This action floods the tray to a shallow depth, wetting the rockwool cubes and coco net pots I have in the tray.  Once the pump stops, the solution drains back into the reservoir and allows air to be absorbed by the plant roots.  I set the timer to irrigate 3 times daily for 15 minutes each time, and this seems to be adequate.

Notice the debris on he bottom of the tray.  

This is coconut fiber that has washed out of the coco pots.

     I also set up a drip irrigation system on the new root veggie bin that is filled with coconut fiber.  This system is simply tied in to the same nutrient reservoir as the germination tray.  I installed a 1/4" drain in one corner of the bin, and this drains back into the nutrient reservoir.  I used coconut fiber because it is a neutral medium, has decent water holding capacity, has a texture similar to high organic matter soil, and has a high cation exchange capacity.  

     CEC is not necessarily something to be concerned about in hydroponics, but in this case, it may be relevant.  CEC is a soil's ability to hold onto positively charged ions of various nutrients such as ammonium.  In hydroponics, nutrients are dissolved in water and are constantly being delivered directly to the roots, so no soil is needed for positively charged cations to bind to for slow nutrient release; the nutrients are always available to the plants.  In soil, a decent percentage (up to 50%) of nutrients are lost and made unavailable to plants due to leaching past the root zone, biological breakdown by microbes, and various other factors; this makes CEC in soil critical for successful plant growth because it allows unused nutrients to bind to soil particles for constant feeding.  Organic matter and clay particles are the only elements of soil that actually have CEC because clay and OM have negative charges.  

     My hope is that with the light irrigation schedule in the coco bin, the coco will basically become super rich soil with plenty of cation binding sites; hopefully a good growing environment for the root vegetables.

     With the addition of this extra level of automation, my germination tray should be more productive even when I'm not out of town because I will not have to water seedlings manually and sporadically.  So, here are some pics of my plants the day before I left: 1/7/12.

 Cilantro and Thyme

 Lettuce and Kale

 Cilantro, lettuce, basil, and fennel

 Carrot

 Radish

 Herbs

 Herbs

 Lettuce and Kale

 Lettuce and Kale

Herbs