Colombia Tests Forage Crops Against Climate Change

Posted on 25 November 2010 by admin

An experimental grass crop at CIAT's Colombian headquarters. Credit:Neil Palmer/Courtesy of CIAT.

By Constanza Vieira*

BOGOTÁ, Nov 25, 2010 (Tierramérica/TerraViva) – Colombia, with 24 million head of cattle, is showcasing two advances towards reducing the 13 percent of climate-changing gas emissions attributed to livestock production around the world.

The key words in this endeavour: brachialactone and Lotus uliginosus.

Brachialactone, a chemical compound discovered in this Andean country on the roots of the African Brachiaria humidicola, gives this grass species the ability to prevent nitrous oxide, a powerful greenhouse gas, from being released into the atmosphere.

This chemical increases microbe fixing of nitrogen and also inhibits biological nitrification, part of the natural nitrogen cycle. This ultimately can reduce the emissions of gases that cause the warming of the Earth’s atmosphere.

At the global headquarters of the prestigious International Centre for Tropical Agriculture (CIAT, for its Spanish acronym), near the southwestern Colombian city of Palmira, scientists had observed nearly 30 years ago that the Brachiaria humidicola grass pasture suppressed soil nitrification.

But till now they did not know why or how it worked.

The experts at the CIAT Tropical Forage Programme, working with the Japan International Research Centre for Agricultural Sciences (JIRCAS) and the Japan National Food Research Institute, discovered and characterised brachialactone.

According to a CIAT brief that explains the research history, the availability of ammonium in the soil triggers and sustains the release of brachialactone.

Latin America has about 80 million hectares of brachiaria pastureland. Which is why CIAT and its partners are studying the benefits of ammonium- dominated farm systems that include pastures with greater capacity for inhibiting nitrification.

“Brachiaria could become the keystone of sustainable crop-livestock systems that have a minimal ecological impact,” said CIAT plant nutrition expert Idupulapati Rao in a statement.

Brachiaria as a forage crop for small cattle operations in Southeast Asia proved successful, according to CIAT, which maintains that it is a nutritious grass that is also appetising to the livestock.

In the tropics, where there is minimal seasonal change, brachiaria is grown in warm and temperate zones, up to 1,800 metres above sea level, a livestock expert, who asked not to be identified, told Tierramérica. It is a very rustic grass that grows easily in soils with low fertility, and is resistant to flooding and drought.

In Colombia, 100 to 200 types of brachiaria grasses can be found.

But this expert said they are not always desirable because they can be aggressive colonisers. Furthermore, the cattle do not prefer these grasses, but are willing to eat them if there is nothing else. Nevertheless, the source acknowledged that the discovery of the brachialactone compound “could be very useful.”

In fact, the Colombian cattle ranching association FEDEGAN prefers to grow autochthonous grasses, which do not need to be reseeded and are much more resistant to pests and disease.

The Brachiaria humidicola species did not work well for FEDEGAN, according to an internal association document to which Tierramérica had access.

In a one-week germination test, just three percent of the humidicola seeds sprouted, compared to an average of 64 percent for five other forage crops, four of them brachiaria species.

While the humidicola is slow to germinate, the Lotus uliginosus, a small leguminous crop used also as forage, is slow to expand and establish itself in a pasture.

The important property of the Lotus uliginosus, known in English as greater bird’s-foot trefoil, is that it reduces the formation of methane in cow intestines. Methane is another of the leading greenhouse gases.

This was demonstrated in a series of investigations conducted over 13 years by 21 students of zootechnology and animal production, led by professor Edgar Cárdenas at the National University of Colombia’s school of veterinary medicine.

Their research into livestock and climate change is taking place in partnership with several universities, including New Zealand’s Massey University.

“Once established, bird’s-foot trefoil is a perennial plant that doesn’t need to be reseeded. It only needs minimal fertiliser, in contrast to the urea-based fertiliser which causes so much environmental damage,” Cárdenas told Tierramérica.

The forage crop adapts well to the cooler highlands of the Andes, between 2,000 and 3,000 metres above sea level.

Uruguay and Argentina have an immense genetic bank of this legume genus, according to Cárdenas, an expert in greenhouse gases. Along with Paraguay, the two countries have vast extensions of these forage plants.

Once ingested, bird’s-foot trefoil dramatically reduces the amount of nitrogen (a source of nitrous oxide) being eliminated through urine and decreases the methane produced in the digestive process of ruminant livestock.

The legume protein is not degraded but instead is absorbed by the cow’s intestine. For dairy cows, it means five more litres of milk produced daily, and the milk itself has “14 percent more protein and 11 percent more fat,” said Cárdenas.

The bird’s-foot trefoil had its time in the spotlight in September, during a field day that drew more than 600 Colombian ranchers to a private farm near Bogotá.

The livestock producers were excited “when they saw the results of the herd’s milk production,” said Cárdenas. “They went home amazed. The million- dollar question is when will they want to adopt it? That does depend on each rancher,” he said.

One of their objections is that this type of pasture, depending on how it is planted, takes six to nine months to establish itself, compared to two or three months for other forage species.

Cárdenas responded, “The immediateness of the rancher’s attitude means they don’t think about sustainability but rather about short-term gains. They want everything right now,” which prevents them from seeing that bird’s-foot trefoil “can reduce the need for nitrogen-based fertilisers” and save them money in the medium term.

While renewing pastures with perennial ryegrass (Lolium perenne) costs about 675 dollars per hectare, the cost of Lotus uliginosus is just 512 dollars. Maintenance of a pasture mixed with ryegrass costs 2,920 dollars per hectare, versus 620 dollars for the bird’s-foot trefoil, according to Cárdenas.

But the professor said he gets impatient with the numbers because the crux of the matter is to reduce greenhouse gas emissions, which also affects the export potential of the livestock.

“Today, in order to export, the international markets impose restrictions based on the carbon footprint. A product with a high greenhouse gas emissions rate won’t be purchased from abroad, and we’ll never get to export, because our livestock operations are high emitters,” he warned.

* This story is part of a series supported by the Climate and Development Knowledge Network http://www.cdkn.org. (END)

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