Composting and Building a Biodigester

My class has been traveling around the Mekong Delta since Monday, September 17.  We spent two nights in Can Tho City before traveling to Hoa An Village in the Hau Giang Province.  In Hoa An we stayed at Can Tho University's school of Rural Development and Agriculture.  We attended lectures by professors from Can Tho University, interviewed local villagers, helped a farmer make compost, helped harvest rice, built a biodigester, attended Vietnamese language class, learned about organic farming, and started to discuss topics for our Independent Study Projects (ISP).

We took a motor boat to the farmer's house where we helped compost and learned about organic farming.

We are aerating the compost pile so the farmer can use organic fertilizer instead of buying chemical fertilizer.

We shoveled the compost into a mound that was six layers tall. Each layer was 10 cm and after each layer was added we sprayed on water that had been mixed with a powdered fungus to speed up the composting process. Then the compost was covered with a tarp, and after three months the farmer can use the organic fertilizer on his field. His field was almost 100% clay so he definitely needed to use some type of fertilizer to be able to grow crops like long beans and morning glory. Professors at Can Tho University try to educate people about the benefits of organic farming. Since most people live next to a body of water, all of their farming and household waste products usually leak into a nearby river.  By making their own fertilizer, the farmers can diminish the amount of pollution in their water system. However, it is time consuming and labor intensive so many farmers still use chemicals. 

Harvesting rice by hand.

I've been asked if Vietnam has a monoculture of rice, but that is not true at all.  The Rice Institute we visited last week said they create about ten new varieties each year.  Also, each farmer uses different varieties of rice depending on their location.  If they are in an area that floods three feet a year, they have to have rice that will grow quickly to rise above the flooding waters.  Most rice that is sold from Vietnam is a combination of ten or more varieties, which makes it very hard for Vietnam to get a high price for it. After farmers harvest the rice and sell it, the rice still needs to be processed to remove the outer husk. In the processing plants a lot of the rice gets mixed up together then packaged. Currently, the government is trying to implement programs to have larger farms only produce one variety of rice so that they can package one variety of rice at a time.

Making a biodigester for a family.

The biodigester is made out of three long bags of polyester.  The bags are placed inside of each other then each end was wrapped around a clay tube.  In the photo we are wrapping strips of rubber motorcycle tires to secure the polyester bag around the tube. All of the supplies cost $200.

After the rubber strips were wrapped around the end of the clay tube, we twisted metal wire around the rubber then covered the rubber in packaging tape.  

When it rains it pours...

 It rains almost every day now because it is the rainy season.  We had to take a break and wait for it to stop pouring before we could continue.The professors and farmers kept reiterating how climate change was effecting Vietnam. They use to be able to predict that it would rain every afternoon, but now it rains randomly.  They are also concerned that if sea levels rise and typhoons get more violent, then they will have a harder time growing crops.

We also put a shorter two-layered polyester bag that will hold the methane gas above the first roof of the pig pens.

Biodigester is in position.

The biodigester is in a hole and now it just has to have tubes attached. One needs to allow the pig waste to go in where it will decompose for 28 days before creating enough methane gas for cooking use. The second tube needs to allow the methane gas to flow into the bag above the pig pen.  And the third tube needs to let the decomposed waste be released into a pond to feed the fish.

The meal we had at the farmer's house after helping with the biodigester: grilled fish, long beans, papaya soup, rice, fried tofu, rambutans, and bananas.