farmblog towards actually sustainable farming in Ahualoa

August 28, 2010

New document on Tea in Hawai’i

Filed under: tea — ben @ 11:58 pm

The full name of the document is “Specialty Crops for Pacific Island Agroforestry: Farm and Forestry Production and Marketing Profile for Tea (Camellia sinensis)”.  It’s online at agroforestry.net (or directly to the PDF).

I contributed a bit to the document, with some reviewing, an illustration of using ginger as a mulch, and some notes on economics.  I’m quite happy with the result, which in 32 pages manages to describe a great deal of what someone needs to know to grow tea in Hawai’i, and process and market it.  There’s also some eye-opening statistics about tea in the rest of the world, where the cost of production can be 50x less.

A lot of this information is hard to come by unless you have one of the tea textbooks (the spotty Hajra book from India, or the wildly expensive Willson book from the UK), so it’s great that much of the important knowledge is now online for free.

Meanwhile, our tea continues to grow with astonishingly well.  I am baffled by the textbooks which say tea should be “pruned back once every 3–4 years to a height that is comfortable for plucking.” Our tea only takes a few months to go from flat hedges to a wild, tall, profusion of growth.  If this keeps up, it will need serious pruning twice a year just to keep it harvestable.  Perhaps more frequent and aggressive plucking would help keep it under control, but there there are many other things on the farm (and building the new house) which distract from harvesting.  One thing is for sure: the conditions here are very, very good for tea.  The soil (just compost, biochar, & mulching) and wet Hamakua weather seem to be perfect.

August 2, 2010

Biochar: from kiln to pit

Filed under: biochar — ben @ 12:29 am

Those of you following the biochar-hawaii list know that i’ve stopped using my kiln, and am now focused on making biochar in a pit. This is both for reasons of scalability and wear; my 55-gal steel drum kiln/retort could only make ~23-gal of char, and the surrounding kiln blocks cracked from repeated heating.

Hence, a pit. Mine is lined with blocks for clean char and easy unloading. Continuously fed wood, pyrolysis occurs at the air-starved bottom of the pile, gradually the pit fills up, then i cover and let it cool for a day, before opening and scooping out the finished char:

That first small pit worked well, so i made it bigger and sure enough, it scales well:

Width Length Depth Gallons Cubic feet # of blocks Gallons of Char
24 32 16 53.2 7.11 33 16.5
32 48 16 106.4 14.22 48 34
32 48 24 159.6 21.33 60 68
32 48 24 On second burn: 82

That 82-gallon operation took 2.5 hours to do the burn, then 2.25 hours the next day to unload, crush, sort, sift, and load into buckets. That’s 82/4.75 = 17.25 gallons of char per hour of work. That’s not bad, given that i’m working with some cheap concrete blocks, a piece of old corrugated roofing, and a shovel. With more money and technology, like a continuous pyrolysis machine, you could certainly get vastly more char per hour of labor, but those machines start at $100,000. I’m feeling quite happy about my pit. The Biochar2010 album has all the pictures.

I gave a biochar talk to the Kona Coffee Grower’s Association on June 2. 10 minutes of that talk got uploaded to YouTube. I then addressed the Hawaii Tropical Fruit Growers on July 19, that time with a fancy presentation with charts and pictures. Next will probably be an evening talk in Waimea on August 8, and then a 1-day workshop on making and using biochar here at our farm, date TBA.

Powered by WordPress