More than 80% of Argentina’s crop farmers use no-till production methods and they are considered among the world’s leaders in this sustainable agricultural technology. However, as in any country with a well-established commercial farming sector, production conditions vary according to area and site. Differences include climate and weather, topography, soil type and fertility, pests and diseases, and accessibility to markets.
So while farmers follow the basic no-till principles, they adapt their specific production methods to the farm’s production conditions to produce the highest yield at the lowest cost for the greatest profit. La Asociación Argentina de Productores en Siembra Directa (Aapresid) – The Argentina Association of Direct Seeding [No-till] Producers – promotes and researches no-till production in Argentina.
On fertile soil
Luciano Martin is a crop farmer, an agricultural input supplier and a consulting agronomic engineer from the Chacabuco area in Argentina’s Buenos Aires Province. All this gives him intimate knowledge of the varying crop production conditions, opportunities and challenges he and his fellow no-till farmers contend with daily.
“My two brothers and I are shareholders in a 600ha, 100% no-till crop farm,” he explains. “Contractors prepare the lands, plant and manage the crop and harvest it. I manage everything, ensure the appropriate crop cultivar choice and see to it that the contractors follow my crop management programmes. Our lands are on the very high-potential soils of the Humid Pampas.”
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This area is an extensive region of flat, fertile grasslands. Martin’s crop rotation cycle mainly consists of yellow maize in summer, wheat in winter, and soya beans in summer. In any summer, the farm has 200ha yellow maize, 200ha short growing season soya beans and 100ha of longer growing season soya beans in the soil. In winter, the farm grows 200ha wheat.
Wheat is typically planted in June, but sometimes in late May or late July, depending on weather conditions and cultivars being planted. Wheat is usually harvested in mid-December. “Right after harvesting 200ha wheat, we plant short growing season soya beans to harvest in late April. The land then lies fallow until we plant 200ha yellow maize in late September. We harvest the maize between the end of March and mid-April, than leave the land fallow until we plant 100ha long growing season soya beans around late October to early November,” says Martin.
In the Humid Pampas with an average annual rainfall of 1 000mm, crops are farmed dryland. Farmers prevent water erosion, promote rainfall penetration into soil and retain soil moisture for crop growth. The no-till principle of retaining organic matter as soil cover is key to achieving this goal. Farmers also minimise weed growth by applying herbicide strategically and by smothering weed growth by using as much organic soil cover as possible.
Martin explains that soya beans with a longer growing season currently yield about 4t/ ha to 5t/ ha, while short-season cultivars yield from 2,5t/ha to 3,5t/ha. “The longer season soya beans use soil moisture retained throughout the previous winter but the shorter growing season cultivars have far less soil moisture because the preceding winter wheat crop used much of it. Even though our winters are mostly dry, the soil cover from the residue of previous crops helps retain soil moisture.”
Dryland wheat yields 4t/ha to 5t/ha while yellow maize yield from 9t/ha to 11t/ha. The typical daytime summer temperature in the Chacabuco area ranges from 25°C to 30°C. During the past five years, the temperature has sometimes reached 40°C for several days at a time. While this had a negative effect on summer crops, its effect would have been worse without the mulch that helped keep the soil cool to reduce moisture loss.
“Controlling weeds is very important for Argentina’s no-till crop farmers,” stresses Martin. “We make sure that weeds don’t use the soil moisture intended for crops. As most of our crop farmers plant Roundup Ready and/or Bt genetically modified maize and soya beans, we can use glyphosate to control weeds. We control any weeds that are tolerant to glyphosate with 2,4-D or Dicamba.”
Heavy crop residue
Canon Gialdini, who farms in partnership with his brothers, is one of the farmers whom Martin consults. For the past 35 years, Gialdini has managed the family’s cropping enterprise, currently consisting of 1 000ha owned and leased lands in the Chapuy area of Santa Fe Province adjoining Buenos Aires Province. He has used no-till methods for the past 20 years. The other brothers manage the 250 breeding sow Pietrain commercial piggery and a commercial beef enterprise in San Luis Province, 50km west of Chapuy.
Gialdini and Martin converted from conventional tillage to no-till to benefit from the soil conservation, improved moisture retention, good soil organic matter content and improved soil health it offers. “As water is a limiting factor for high yield in Argentina, we must use our rainfall efficiently,” Martin explains. Crop production conditions in the Chapuy area differ only slightly from those Martin has to manage.
“We use the same crop rotation that Luciano [Martin] does,” Gialdini says. “Our dryland crops yield about 10t/ ha for yellow maize, about 4t/ ha for longer growing season soya beans and about 3,5t/ ha for shorter growing season soya beans.”
Gialdini aims for maximum organic matter soil cover, but points out that excessively thick cover can cause the soil to be too cool at planting, with the potential to inhibit crop seed germination. “Our planters are designed to deal with heavy crop residue,” he explains. “Their row cleaner attachments create a narrow strip of exposed soil on the planting rows, enabling sunlight to warm the soil to improve seed germination. I’ve found that seed planted using row cleaners germinates a day or two sooner than seed planted directly into the crop residues cover.”
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He adds that, to optimise germination in thick crop residue, the seed variety must tolerate cooler soil. For maximum germination, he combines these management strategies with weather forecasts to select the warmest time for planting, even if he has to delay the usual planting date. At one stage, he planted maize and soya beans at a 70cm inter-row spacing but now plants at 52cm to increase the plant population and corresponding grain yield.
However, reduced spacing can cause undesirable inter-row crop residue windrowing. To prevent this, he plants only when the residue is drier and more brittle, even if this has to wait till after midday when the sun has dried the residue. “We plant soya bean seed at about 350 000/ha to aim for least 300 000 plants/ ha, or a density of 30 plants/ m²,” he says. “Yellow maize seed is good at 80 000/ ha for 70 000 plants/h to 75 000 plants/ha. Wheat seed is planted at 130kg/ha.”
Late frost in spring kills many weeds and Roundup Ready volunteer plants on Gialdini’s lands before he plants. However, a day or two before planting, he applies a combination of glyphosate and either 2,4-D or Dicamba to ensure that no weeds or Roundup Ready volunteer plants compete with the young crop for moisture, nutrients, space and sunlight.
Neither Gialdini nor Martin put livestock on their lands to graze crop residue, as the high-potential soil of the Humid Pampas is more economically rewarding used only for crop production. The soil is sensitive to compaction and is prone to damage by livestock hoof action. They don’t want to lose any organic soil cover and are determined to produce and protect it as it is adequately decomposed by rain, sunshine and soil microfauna to release nutrients back to the soil.
Gialdini does not waste the slurry from his family’s piggery. While the nutrient value of the slurry is uncertain, soil analysis of slurry-treated lands reveal no deficiency in nutrients important for soil health and crop production. Consequently Gialdini has applied no chemical fertiliser to these lands for six years, saving the cropping enterprise money.
No-till 20 years on
La Tenuta, a 3 000ha no-till crop farm, lies about 10km from the town of Santa Eufemia in the south of Córdoba Province. Belonging to the Argentinian mega-company Aceitera General Deheza (AGD), it grows, processes and exports oilseed and grain crops and their derivatives. La Tenuta has lower potential soils than those farmed by Martin and Gialdini.
The average annual rainfall is 600mm to 700mm, significantly lower than that of other parts of the Humid Pampas but yellow maize, soya beans, groundnuts and wheat crops are not irrigated. La Tenuta’s manager Nestor Garnero and one of its agricultural contractors Claudio Tavecchio attribute this mostly to the fact that the soil has not been tilled for the past 20 years.
“When AGD bought the farm, it had been used for many years for mixed cropping and livestock farming,” says Garnero. “The soil was very compacted. Before we could convert to no-till, we put in a double-action disc and ripper to break the compaction layer. We have never again tilled the soil and will never do so.”
This enterprise decided to incorporate precision farming methods to varying degrees in crop production depending on the individual crop. For the past three years, all La Tenuta’s soil, seeding, fertilisation, chemical application and yield data have been digitally mapped. Starting with the coming 2014/15 summer production season, it will use a complete precision agriculture system.
For the foreseeable future, the remaining crops will be grown using a GPS data and planter monitoring system.
Every summer, between 38% to 40% of the farm’s 3 000ha crop soil is planted to yellow maize and soya beans respectively and about 15% to 18% to groundnuts.
“We plant a groundnut crop on land only every five years. Harvesting the nuts disturbs the soil surface, something that we want to limit as much as possible in our no-till approach,” says Garnero. ”While we don’t grow winter wheat for our own use, we grow some on contract for outside buyers. We used to leave the soil fallow after harvesting groundnuts and soya beans where we weren’t going to plant winter wheat.
This resulted in wind and water erosion as groundnuts leave very little organic residue on the surface. We now experiment with rye as a winter cover crop instead of winter wheat after soya bean and groundnut crops. Rye uses less soil moisture than many other cover crops and grows quickly. We’ll kill it off with herbicide at between knee and waist height in about August, and plant a yellow maize crop into the residue.”
To prevent soil compaction from the wheels and to distribute root growth throughout the soil, every subsequent crop on La Tenuta is planted at a 30° angle to the planting direction of the previous crop. This root growth improves soil structure and organic matter content and enhances moisture penetration into the soil.
AGD has signed an agreement with multi-national crop technology company Monsanto to plant the latter’s stacked gene Roundup Ready and Bt yellow maize and soya bean cultivars. Garnero explains that these genetic modifications are particularly beneficial in longer growing season cultivars that are exposed to pests and weeds for longer than their shorter growing season contemporaries are.
“These are working well. A trial nearby with non-genetically modified long growing season yellow maize and soya bean cultivars ended with the crops almost being wiped out by pests,” Garnero points out. A document on no-till, published by Argentina’s Instituto Nacional de Tecnologia Agropecuaria (National Institute of Agricultural Technology) and its Ministerio de Agricultura, Ganader?a y Pesca (Ministry of Agriculture, Livestock and Fisheries) explains how widely used and successful no-till is in the country. It concludes (translated):
“It is well-known that Argentina is the world leader in the adoption of direct planting (no-till) technology, using it in 81% of its surface area, representing 27 million hectares. Argentina evolved from producing 980kg of grain per capita per year in the 1970s to 1 218kg per capita per year in the 1990s. Argentina is now the country with the highest grain production per capita per year worldwide, with a figure of 2 309kg per capita per year. This was not only due to direct planting (no-till) but to a series of technological and socio-political factors.”