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Forage grass curbs nitrous oxide

<em>Brachiaria</em> has been shown to inhibit nitrification, helping to reduce greenhouse gas emissions from agriculture (© Neil Palmer (CIAT))
Brachiaria has been shown to inhibit nitrification, helping to reduce greenhouse gas emissions from agriculture
© Neil Palmer (CIAT)

First observed in the 1980s, the potential for large-scale use of Brachiaria grass to inhibit the conversion of nitrogen fertiliser into nitrous oxide has recently been documented, following 15 years' collaborative work. The findings of a joint team from the International Center for Tropical Agriculture (CIAT) and Japan International Research Center for Agricultural Sciences (JIRCAS), offer what CIAT's lead forage researcher, Michael Peters, believes "could be agriculture's best bet for keeping global climate change within manageable limits."

Several years ago, JIRCAS scientists made a major breakthrough, discovering the chemical substance emitted by plant roots that causes 'biological nitrification inhibition' (BNI). CIAT scientists then validated the concept in the field, demonstrating that Brachiaria grass suppresses formation of nitrous oxide (a greenhouse gas 300 times more potent than carbon dioxide), compared with another crop, soybean.

According to the latest findings, CIAT scientists have now found ways to increase the BNI effect through plant breeding in different species of Brachiaria. They also show that a maize crop grown on former Brachiaria humidicola pastures gave acceptable yields with only half the amount of nitrogen normally used, because more nitrogen was retained in the soil. Hybrids of Brachiaria have now been delivered to farmers in Colombia and Nicaragua for productivity and quality testing.

"This approach offers tremendous possibilities to reduce nitrous oxide emissions and the leaching of polluting nitrates into water supplies, while also raising crop yields through more efficient use of nitrogen fertiliser," said G.V. Subbarao, a senior scientist at JIRCAS. Other research has shown that deep-rooted, productive Brachiaria grasses capture large amounts of atmospheric carbon, on a scale similar to that of tropical forests - a further plus for climate change mitigation.

Date published: September 2013


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