Carlos Crovetto, President of the Chile No-Till Farmers Association, has not ploughed his central Chile farm for 20 years and has witnessed significant changes in the structure and fertility of its old eroded soils.
Mr Crovetto told WANTFA's 2001 Conference, in Perth, that the increased level of organic matter in his soil reflected the increase in yields from rotations of wheat, riticale, corn and lupin.
"The rotation of irrigated corn and dryland wheat will annually leave 12 t/ha of stubble over the soil," he said. The resultant larger amount of biological activity increases organic carbon levels.
Stubble quality is also important, he said. "Those stubbles with high carbon/nitrogen relationships are the most beneficial to the soil," he noted.
According to Rolf Derpsch of Paraguay, controlling soil erosion remains one of the main driving forces for no-tillage adoption in South America.
He also highlighted the practice of adequate crop rotations, including green manure cover crops, as the likely main factor behind successful and widespread adoption of the technology in Latin America
Brazil lifted its no-tillage adoption from 1 million hectares in 1990 to 13.47 million hectares in 2000, Argentina from 300,000 ha to 9.25 million hectares, and Paraguay from 10,000 ha to almost 1 million hectares in the same period.
Economic arguments rule
Mr Derpsch said it's the same the world over: farmers adopt technologies because of positive economics and seldom because they are environmentally friendly.
"Therefore, an economic evaluation of the system tinder the different agro-ecological and socioeconomic conditions is essential to have better arguments for adoption."
He urged an "evaluation of the whole system, with all its components — putting value to timeliness, longer life of tractors and less repair costs, improvement of soil fertility, reduced costs for fertilisers and pesticides, and the environmental benefits of the system".
He said economic studies have shown that economic returns of no-tillage could be substantially increased by the use of crop rotations and green manure crops.
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