Chinese yam (Dioscorea polystachya) produces small aerial tubers ("yamberries"), which grow on the vine like berries but are in fact tubers. They are very good cooked starchy vegetables and a potential market crop and no-till perennial staple food for temperate climates. It takes several years until the yields really kick in, but data on those yields is unavailable. Let's generate that information together.
The goal is to measure the yields of yamberries on vines 3, 4, and 5 years old.
Each participant should build a trellis for easy harvest of the aerial tubers. When they are ripe you should have easy access to place a tarp or blanket under the trellis. Shaking the vines will result in almost all of the yamberries falling to the tarp for easy collection. Trellises should be fairly sturdy as the vines can grow 15-20 feet high and are robust. Report how many square feet of ground your trellis will cover. Mine will be a horizontal cattle panel 4x16', laid flat at 5' high, supported by metal t-posts.
After you build your trellis, plant your yamberries and care for them until they are mature beginning in year 3. At that point, harvest and weigh your aerial tuber yield each year for years 3, 4 and 5. After weighing them you can eat them! Boil them for 10 minutes and add salt, they taste just like new potatoes. Or add them to stews in the last 10 minutes or so. After the year five harvest, if you like, you can dig up the "mother tubers" underground. They are brittle but large and delicious.
I can send yamberries this fall to folks in the US, or you can order them from Oikos Tree Crops, that's the source of the variety with the largest aerial tubers that I am aware of.
I've collected lots of data from other authors on the yields of perennial staple crops, collected in The Carbon Farming Solution. I'm curious about this particular crop as it fills an important niche for cold climates - perennial starchy no-till staple crop.
Are you seeking volunteer growers or other types of volunteers?
Yes, seeking volunteer growers
What will you ask volunteers to do?
Build a trellis, care for the vines, harvest and weight the crop for years 3, 4, and 5. Report the area of your trellis so we can calculate the yields in pounds per square feet, and ultimately convert to kg/sq meter.
Other requirements of volunteers?
Participants should be in a temperate climate, USDA zones 4-8. Dioscorea polystachya is considered weedy in some areas and considered highly invasive in Tennessee and Kentucky. It is not illegal to grow anywhere in the US as of 2018. Please be thoughtful about where you plant it if this is of concern in your area. If your region is dry, you'll have to irrigate.
Can volunteers expect to be able to keep some germplasm (seeds, bulbs, cuttings, spores, etc) at the close of the project?
Yes, of course