The stubble that help save the planet

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Text from @BBC

More droughts , floods and extreme weather events : most scientists believe that these are some of the consequences of global warming , a phenomenon that occurs by the production of harmful gases trapped in the atmosphere.

According to a recent report by the World Meteorological Organization (WMO) , the concentration of greenhouse gases reached a new record in 2012 . If the trend continues, warns the body – the end of this century global average temperatures could rise by more than 4 degrees , which would have ” devastating consequences ” .

How to stop this catastrophe ? In its latest report , published in early November, the United Nations Program for Environment ( UNEP) , suggested a number of changes that could be implemented to reduce greenhouse gas emissions. And one of those changes have to do with agriculture, which the UNEP contributes about 11% of emissions of greenhouse gases .

According to the agency, the environmental damage generated by agriculture could be reduced substantially if the world adopted a farming technique that is widely used in most southern countries of South America, where it has managed to cut more than 250 million tons of greenhouse gases since the 90s .

This is the direct seeding , a system that requires no plowing , uses very little farm machinery and achieves significantly reduce emissions of carbon dioxide (CO₂) , one of the main greenhouse gases .

Farmers in Argentina, Brazil, Uruguay and Paraguay are leading the world to implement this method , which is also used on a smaller scale in the United States, Australia , and China, among others.

While globally 8% of the land use direct seeding in the Southern Cone over 70 % of sown area is cultivated in this way , according to the UNEP , and so the agency urged everyone to follow the American example .

What is direct seeding ?

Also known as no-till or conservation tillage, direct seeding is a way to cultivate the land without removing the stubble or crop residues remaining when doing the previous harvest.

In traditional agriculture land is plowed before planting seeds and soil removed the residues remain buried , causing decay and emit CO ₂ .

In contrast, direct seeding these residues remain on the ground, forming a layer that protects the soil from erosion. Using special drills , the seeds are placed drilling this organic matter .

According to the proponents of this technique , in addition to caring for the earth direct seeding also allows more efficient use of water.

The rain falls on the stubble , so as to prevent erosion generated by the blow of the drop, and water penetrates the soil gently . Instead, without the protective layer water quickly saturates the surface of the earth and begins to accumulate” he told BBC Santiago Casas, general coordinator of the Association of Producers Argentina tillage (Aapresid) .

With more land protected from erosion and better hydration, non-tilled field “achieved high production levels with temporal stability and harmony with the environment ” says the Aapresid in place , an NGO established in 1989 to promote direct seeding .
less machinery

This technique also has indirect ecological benefits : by not plowing requires fewer machines , reducing fuel use , which also cuts the emission of harmful gases .

According to Santiago Lorenzatti Argentine agronomist , whose thesis on tillage was cited in the UNEP report , so do not depend on this technical machinery can produce 123 kilograms of grain per liter of fuel, while the conventional system produced 50 kilos.

The expert told BBC that direct seeding cultivation costs no more than traditional planting and produces similar amounts , although in the long term, the best floor care enables even higher performance.

The Kenyan Henry Neufeldt , expert World Agroforestry Centre ( ICRAF , according to its acronym in English) and one of the authors of the UNEP report , told BBC News that the countries of the Southern Common Market (Mercosur ) pioneered direct seeding because they invested heavily in the 90s to transform its technology.

According Lorenzatti regional momentum arose out of necessity. ” Unlike European or American farmers living subsidies largely Latin Americans have to be efficient in order to survive and that’s why we were more innovative ,” he said .

A greater reliance on the use of herbicides to kill weeds is certainly a disadvantage of this technology ” Henry Neufeldt , co-author of the UNEP report

However, most of the world’s farmers are reluctant to adopt this technique. According Lorenzatti The main reluctance is cultural , since many do not conceive the idea of ​​leaving to till the earth, an ancient practice .

For UNEP one of the main obstacles has to do with the initial investment required to transform or replace drills which can pass through the layer of stubble, and other expenses associated with this practice.

But there is another point of resistance that is highlighted in the report, which represents the most direct seeding questioned : by using less machinery, this technique requires large amounts of herbicides such as glyphosate , an agrochemical highly questioned for their possible damage to the health.

A greater reliance on the use of herbicides to kill weeds is certainly a disadvantage of this technology. These herbicides could affect water and insects ” admitted Neufeldt .

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