Rice straw is perceived to have little or no commercial value. But, in Vietnam, where rice straw is turning into a lucrative business, the possibilities are slowly becoming endless.
Le Hoang Thanh has been farming for 15 years. Four years ago, this 37-year-old father of three decided to go in a slightly different direction and collect rice straw from other farms to sell as livestock feed to dairy farms and other companies that needed it.
“The business is doing well,” Mr. Thanh said of his new activity as a rice straw service provider. “I have purchased three additional rice straw balers to hasten the collection.”
Despite his success, he does encounter problems, such as wet straw harvested during the rainy season. The growing practice of using rice straw to cultivate mushrooms could also affect Mr. Thanh’s business because rice straw loses its value after the mushrooms are harvested.
“These kinds of low-quality straw no longer have market value,” said Hung Van Nguyen, a mechanization and rice by-product scientist at the International Rice Research Institute (IRRI).
Expanding rice straw management
In 2017, scientists at IRRI and Hohenheim University, seeking to find a way to use low-quality rice straw, developed a machine that converts rice straw into composting material. Known as the rice straw compost turner, the machine is attached to a 160-horsepower (hp) tractor.
A heap of rice straw and cow dung is laid out in the field. The compost turner is loaded with enzyme water concentrate and releases the solution from small nozzles as it passes by the compost heap to hasten decomposition. A mixing shaft refines and mixes the compost ingredients.
This is a promising option because incorporating wet straw into the field to fertilize the soil is still a common practice of many farmers in Asia. Some researchers in Vietnam believe that the technology will be useful in their country because of the growing demand for rice straw and the need for different management options for the 54 million tons of rice straw produced by its rice sector.
However, the size of the original machine is too large to fit the tractors typically used in Vietnam’s farming villages.
“Most farmers in Vietnam use 30‒35-hp tractors,” said Dr. Nguyen. “The original design fits a tractor that is about three times bigger. We need to adjust the size to suit the Vietnamese field context.“
Under Germany’s Federal Ministry for Economic Cooperation and Development, the development and testing of a re-scaled rice compost turner were conducted at IRRI in collaboration with Nong Lam University, Tien Giang University, and Hohenheim University in December 2017. After less than six months, the equipment is now being tested in farmers’ fields in Vietnam.
“I have been using the rice straw compost turner for two weeks, for my pomelos, dragon fruit, and oranges, and I can say that the leaves and roots look better,” said Nguyen Van Hieu from Tien Giang University, one of the proponents of the project. “It is also much cheaper than using chemical and commercial organic fertilizer because you can almost get the materials for free.”
Farmers assessing technologies
Because of his ties with Nong Lam University and Tien Giang University when he started his baler business in 2016, Mr. Thanh volunteered to be a farmer-partner for the field testing of the rice straw compost turner. As a cooperator, he lent his tractor and land for free.
“I learned how to operate the machine and the straw composting process, and I looked for any changes,” he said. “This can be an additional value in my business; it perfectly complements what I have now.”
“Farmers and dairy farms prefer to buy dried straw so they can store it for a longer time,” Dr. Hung said. “These buyers reject the wet straw collected during the rainy season and that used as a substrate for mushroom production. With the rice straw compost turner, straw regarded as waste will regain its value.”
The rice straw compost turner has yet to set the pace in mechanized composting of one of the major by-products of rice production but queries are starting to pour in.
“The challenge now is to double our speed to ensure that this technology will be available in due course,” Dr. Hung said.
The rice straw compost turner is one of the technologies developed under IRRI’s project Scalable straw management options for improved livelihoods, sustainability, and low environmental footprint in rice‐based production systems. The project aims to introduce practical and viable technology options to optimize the use of rice straw without causing harm to the environment and to bring income opportunities to farmers.
Ms. Quilloy is a communication and outreach specialist at IRRI.