High and dry

 Adam Barclay   |  

On a steaming hot Beijing day in August 2007, a group of researchers from China Agricultural University (CAU) visited their experimental station on the edge of the gigantic city. Several hectares of what has come to be known as aerobic rice—grown like any other nonrice crop, in unflooded fields—stood oblivious to the brutal, unforgiving sun.

This is why Rice Today was in China. The push to establish a large-scale aerobic rice production system, which achieves high yields using a fraction of the water required for flood-irrigated rice (known simply as lowland rice), is gaining momentum. There are wrinkles to be ironed out, but the potential, in the face of widespread and ever-worsening water availability, is enormous.

On this day, though, it wasn’t the aerobic rice that grabbed our attention. As we climbed into the car to head back to the university campus, Huaqi Wang—the breeder responsible for the several aerobic rice varieties we’d inspected—turned to us.

“Before we return, I want to show you something,” said Prof. Wang, director of CAU’s Upland Rice Research Center.

Without any explanation, we drove to another rice field, a few kilometers away. This half-hectare of healthy looking rice, belonging to a local farmer, represented something truly momentous. It was the last remaining plot of commercial lowland rice in the municipality of Beijing.

Making a point about aerobic rice: IRRI water scientist Bas Bouman. (Photo: Ariel Javellana)

Making a point about aerobic rice: IRRI water scientist Bas Bouman. (Photo: Ariel Javellana)

With a wry laugh, Prof. Wang told us that soon it would be gone too, muscled out by a still rapidly growing population and fast-encroaching urban and industrial works, whose prodigious hunger for land and thirst for water mean that there simply isn’t enough of either for lowland rice.

CAU water expert Xiaoguang Yang, who researches water-saving agricultural technologies, says that the water situation, especially in northern China, has become desperate. “In Beijing,” she says, “the groundwater depth is very low—at least 20 meters below the surface and dropping further every year.”

Beijing, in China’s north, is home to more wheat and maize than rice, but the field in front of us symbolized not only a dying practice but also the promise of water-saving technologies like aerobic rice. Perhaps, we lamented, it should be preserved as a museum exhibit.

According to Prof. Yang, as recently as 10 years ago, a lot of lowland rice was grown in Beijing. “Now,” she says,” apart from this field, there’s none. But people here want rice—therefore, we need aerobic rice.”

When water is scarce, rice is inevitably the worst-affected crop. Compared with the world’s other major staples, wheat and maize, rice uses around twice as much water—roughly 2,000 liters to produce a single kilogram.

Plant nutritionist Shan Lin, from CAU’s Department of Plant Nutrition, points out just how thirsty lowland rice is. “In China, 70% of water is used in agriculture; 70% of that is used in rice production,” he says. “In terms of rainfall or irrigation water, lowland rice needs approximately 1,000–1,500 millimeters. Aerobic rice needs around 600 millimeters. Aerobic rice can really help us save water.”

Bas Bouman, senior water scientist and aerobic rice work-group leader at the Philippines-based International Rice Research Institute(IRRI), is acutely aware of this problem. When he arrived at IRRI in 1999, Dr. Bouman had an idea: why can’t we grow rice as an irrigated but unflooded dryland crop, like wheat or maize? There already existed upland rice crops—traditional varieties that yield poorly but are able to cope with extremely harsh conditions, including very dry climates, poor soils, and often sloping land. What if the sturdiness of upland rice could be combined with the highyielding traits of lowland rice?

So, in 2000, Dr. Bouman started asking agronomists and plant physiologists about the idea.

“The answer I always got,” he says, “was, ‘It’s just not possible—rice is not like that, rice is different.’ So I parked the idea for a while, until I learned about the work to improve upland rice in more favorable environments. There were people at IRRI with basically the same idea, but not in the irrigated lowland environment. They were working in the sloping uplands, trying to improve upland rice.”

Like most good ideas, aerobic rice was, in theory, fundamentally simple. It also turned out that it wasn’t the first time somebody had thought of it. The IRRI upland researchers introduced Dr. Bouman to Prof. Wang, who, at that time, had been working on aerobic rice for more than a decade. Sure enough, he had crossed hardy upland rice varieties with modern lowland varieties.

“I realized that what Prof. Wang was doing was exactly what I had in mind and that, yes, it is  possible,” recalls Dr. Bouman.

Anhui province farmer Guangyun Dai shows off one of his aerobic rice plants. (Photo: Adam Barclay)

Anhui province farmer Guangyun Dai shows off one of his aerobic rice plants. (Photo: Adam Barclay)

Prof. Wang’s progress was encouraging—despite very little research support, he claimed to have achieved yields of above 6 tons per hectare. He was working in low, flat areas where farmers have insufficient irrigation to flood the field, but have access to enough water for two or three small irrigations per season or as much rainfall as is needed for wheat or maize. This, says Dr. Bouman, is precisely the target zone for aerobic rice. In water scarce China, it is an environment growing in area every year.

For farmers who have been forced by lack of irrigation to end their lowland rice production, aerobic rice offers the chance to grow rice once more. Rice is so fundamentally important to the diet of most Chinese people that farmers will go to great lengths to grow rice for themselves and their family, even if it means sacrificing income that would allow them to buy rice on the market. It is a cultural as much as an agricultural decision.

“When we say, well, you can also buy it on the market,” says Dr. Bouman, “they look at you and say, ‘yes, that’s fine, but I want it in my backyard.’”

And, another factor further boosts the potential of aerobic rice. Although rainfall in many parts of China is high, it is also very unstable. In such areas, the majority of the year’s rain can fall over a couple of months in summer, causing floods that badly damage or totally destroy traditional dry land crops such as maize and soybean. Aerobic rice, though, can still handle flooding. In a year when rainfall is spread out and no floods occur, a maize crop will yield higher than an aerobic rice crop. But, if the floods hit—and they often do—aerobic rice will give farmers a few tons per hectare, where maize would have left them with nothing.

The day after witnessing Beijing’s last field of lowland rice, Rice Today, with CAU agronomist Guanghui Xie, headed south to Anhui Province, where rice is a much more important crop. The farmers in Anhui are some of China’s poorest—any technology that can increase their water productivity and help them secure rice for their own consumption can also help reduce poverty.

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