Rice farming must address both mitigation and adaptation to climate change: from construction to waste recovery, the solution may be in circularity
By Giorgio Kaldor – Renewable Matter
Rice is among the world’s most important crops. A food staple at the center of centuries-old culinary traditions-from Spanish paella to Japanese sushi, via Italian risotto, Indian biryani and South American arroz-this cereal feeds more than half the global population, providing sustenance for millions of farmers and representing a true cultural and economic pillar. However, its production is deeply vulnerable to the effects of climate change while, at the same time, contributing significantly to greenhouse gas emissions and ecosystem degradation.
Rethinking the entire cycle of this food and the biomass derived from it is possible, however. The circular economy applied to rice farming already offers several solutions for transforming-and adapting-a high-impact agricultural system into a more sustainable model. Indeed, the reuse of by-products, from construction to food production, makes it possible to reduce the release of climate-changing emissions, create new economic opportunities and strengthen the resilience of local communities.
Rice, victim and conduit of global warming
Rice farming is at a crossroads, facing both mitigation and adaptation to climate change. The International Rice Research Institute itself has described rice as“the crop most vulnerable to future climate change.” Although the grains we all know are a source of nutrients for billions of people, their production is in fact increasingly threatened. Paddy fields, which thrive in low-lying ecosystems such as deltas, are vulnerable to rising temperatures and sea level rise, resulting in salt intrusion.
According to a 2018 study published in theArchives of Agronomy and Soil Science, increased frequency of heat waves could reduce rice yields by up to 40 percent by the end of this century. But the challenges don’t end there: the common practice of flooding rice fields encourages the proliferation of microbes that release methane, an extremely potent greenhouse gas and the second largest contributor to global warming after CO₂. In fact, one kilogram of methane has a climate-altering impact 84-86 times greater than carbon dioxide over 20 years and 28-34 times over 100 years.
In this regard, a widespread practice, the burning of rice straw to free up space in fields, has a heavy environmental cost. In fact, burning straw releases huge amounts of CO₂ and methane into the atmosphere, further accelerating climate change.
From waste to green building: building houses from rice
“Italy is the leading producer of rice in Europe,” explains Tiziana Monterisi, bioarchitect and cofounder of Rice House, a Piedmontese benefit company founded in 2016 that designs and creates buildings using innovative, all-natural materials derived from rice processing waste. “Of course, if we compare ourselves with the rest of the world, it may seem small, because we are talking about 0.1 percent of global production. But in reality the amounts of by-products generated are very significant. For each hectare we get seven tons of grain, but we also produce about ten tons of waste and residual materials. We are talking about straw, clay, husks, chaff, ash, starches: they are really numerous. We decided to focus mainly on two of these by-products: straw, which remains in the field after harvesting, and rice husk, which is instead obtained during the processing of the grain. “
The supply chain is concentrated between Biella and Pavia, from where the company collects the raw material within 300 kilometers to process and use it at construction sites in northern Italy and Canton Ticino, Switzerland. “The interesting thing is that those 2 million tons of waste sequestered about 2.7 million tons of CO₂. We certify that value and sell it to companies that want to offset their emissions “, Monterisi adds.
The goal is to create a bridge between two distinct worlds: on the one hand, agriculture, with rice farmers growing and harvesting the grain, and on the other, industry, which processes the raw grain into food. Two main by-products are generated during processing: husk, which is obtained when the rice is milled but remains whole, and chaff, which is produced instead when the grain is mechanically refined to become white rice.
“The production of these by-products is crucial for us, because we are talking about two million tons each year between straw and husks,” Monterisi continued. “A really huge amount. Today, some of these materials are simply burned, especially husks, in biomass power plants. But this is an inefficient use: it has a very low calorific value and burning it releases a large amount of ash, due to the presence of silica, which is an extraordinary component from a chemical point of view. Instead of burning it right away, we started building bricks, insulation, flooring and other products. Only at the end of the material’s useful life can we consider whether to burn it. We stockpile it first, even for five, ten, fifty or seventy years, and in the meantime we build a supply chain that considers burning only as a last option, when the product is no longer recyclable or can no longer return to the field. “
A principle that guides the entire project and becomes the hub of the supply chain. “We collect the raw material and take it to twelve processing centers today. Depending on the product, we have specific plants: there are those who make bricks, those who make prefabricated bricks, those who use husks for blowing, and those who make insulating panels. Behind each product category is an Italian industry. ” The finished product, once ready, comes to the market, but not only the construction one. “And today we are developing a lot of design objects, such as lamps and vases, and accessories such as bags, thanks to a new fabric.”
From rice to mushrooms: straw as a resource, not waste
On the other side of the world, in Vietnam’s Dong Thap province, in Thanh Binh district, small-scale farmers from Tan Binh Cooperative have instead found an innovative way to turn rice straw into a valuable resource through mushroom cultivation. As part of the program “Developing a Sustainable Rice Supply Chain for Smallholder Farmers in Dong Thap Province,” sponsored by the NGO Rikolto together with the provincial Department of Rural Development, the cooperative has initiated a production cycle based on regenerative agriculture that gives new life to waste. Harvested and processed, the straw is used as a substrate to grow, precisely, “straw mushrooms,” a valuable variety in high demand in the market.
“According to the Vietnamese Ministry of Agriculture, Vietnam produces about 43 million tons of rice each year , equal to the volume of rice husk generated,” explains Nguyen Tuan Anh, Rice Program Officer at Rikolto. While China remains the world’s leading producer, Vietnam is the third largest exporter, after India and Thailand. “There are many rivers in the area, which makes it difficult for farmers to keep straw separate from paddy fields. This requires high transportation costs, so farmers usually choose to burn it to save money. The mushroom farming model is a promising economic opportunity because this technique has been popular among Vietnamese farmers for the past three decades. Farmers are familiar with it, and given the abundance of processing byproducts, they can easily utilize this available resource. It offers low production costs and is accessible in fields across the country .”
In just 45 days, the cooperative thus managed to turn 500 bales of straw (about 10 tons) into 700 kilograms of mushrooms, generating a profit of 7.4 million Vietnamese dong (about 284 euros). In addition, the organic-enriched crop residues were converted back into natural fertilizer, bringing nutrients back into the fields and reducing the need for chemical fertilizers. This second life of the straw also earned the cooperative an additional 4 million dong (154 euros). This is a pilot project, but it not only solves the problem of managing agricultural residues, but also creates new economic opportunities for small farmers and strengthens the environmental sustainability of rice production, in line with the international standards of the Sustainable Rice Platform (SRP).
Cover photo by Sergio Camalich from Unsplash
