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A greenhouse gas-suppressing tropical grass could cut harmful methane emissions from livestock while growing more food with less fertilizer, reducing the amount of pollution that ends up in water supplies, research suggests.
A tall order for humble grass, you might think. But given that grassland pastures take up 3.2 billion of a total 4.9 billion hectares of land globally, grass has ample room to deliver, researchers argue.
Papers presented this week at the 22nd International Grasslands Congress in Sydney, Australia, show that one tropical grass in particular has the potential to suppress the aggressive greenhouse gas nitrous oxide.
With a global warming potential 300 times that of carbon dioxide, nitrous oxide makes up about 38 percent of all emissions in agriculture, which accounts for almost a third of total climate-changing emissions worldwide.
But the roots of the grass Brachiaria humidicola release inhibitors that suppress nitrification – the biological process that turns nitrogen from fertilizer into nitrous oxide and releases it into the atmosphere.
This “inhibiting” factor, known as Biological Nitrification Inhibition (BNI), offers “what could be agriculture’s best bet for keeping global climate change within manageable limits,” said Michael Peters, leader of the forages program at the International Center for Tropical Agriculture (CIAT).
“BNI defies the widespread notion that livestock are necessarily in the minus column of any food security and environmental calculation,” Peters continued, describing this low “hoofprint” grass solution as a triple-plus for farmers, livestock and the environment.
Although BNI has been known about for years, scientists at CIAT and partnering Japan International Research Centre for Agricultural Sciences (JIRCAS) have only recently found ways to quantify and boost BNI in livestock feed, specifically Brachiaria grasses.
Successful field trials have proven that BNI in Brachiaria humidicola suppresses nitrous oxide release by an impressive 90 percent, as compared with soybean, for example, which lacks this ability.
With support from the German government, farmers in Colombia and Nicaragua are already evaluating highly productive hybrids of Brachiaria humidicola - 30 percent more productive than other grasses currently on the market - as researchers identify the next steps to scale-up use of the grass.
Other benefits include, for example, less fertilizer use. Since more nitrogen is retained in the soil, less fertilizer needs to be applied to crops grown after grass pastures. Maize grown after Brachiaria gives good yields with only half the amount of nitrogen fertilizer normally applied.
Halving the amount of fertilizer applied to soil has huge implications on cost as well as the environment. Currently, a whopping 70 percent of the 150 million tons of nitrogen fertilizer applied to the soil globally – valued at an estimated $90 billion each year - is essentially wasted.
“The problem is that today’s crop and livestock systems are very ‘leaky’,” said Guntur Subbarao, senior scientist at JIRCAS. “This approach offers tremendous possibilities to reduce nitrous oxide emissions and leaching of polluting nitrates into water supplies,” he added.
Intercropping Brachiaria livestock pastures in maize or soybean fields in the tropics could boost the BNI factor and its benefits on a massive scale, making crop systems more sustainable. All of which is not bad, for grass.
This research is part of LivestockPlus – a wider initiative of the CGIAR Research Program on Livestock and Fish. Led by the Kenya-based International Livestock Research Institute, the programme aims to increase the availability and affordability of meat, milk and fish for poor consumers, and raise incomes through innovative research on tropical forages and grasses.
Georgina Smith is communications specialist for Southeast Asia for the International Center for Tropical Agriculture (CIAT).