South America Calling

Significant rain fell in central Brazil this week. A front sweeping northward brought areas of 25-75 millimeters (roughly 1-3 inches) of rainfall from Mato Grosso to Minas Gerais. The rainfall was enough to officially start the wet season for the region and probably got some producers out with their equipment to plant soybeans. However, the conditions are changing and producers that are planting may have to worry about dryness in the week ahead.

The front that was responsible for producing the rain sat over central Brazil for several days this week but has since fizzled out. In its place, drier weather has returned. Models are very insistent on only spotty rains across the region going into early October and mostly in western Mato Grosso, closer to the Amazon rainforest.

With temperatures rising into the middle to upper 30s Celsius (lower 90s to lower 100s Fahrenheit), any rain that fell this week will quickly dry up. Producers that decided to plant soybeans with the first heavy rains may be in for issues.

Seeds that germinate have no subsoil moisture to rely upon as the dry season came with four months of no rainfall. Plants can easily die in the heat and the need to replant is higher this year until those wet season rains become more consistent. Other producers who decided to wait may find a benefit in doing so, but they also risk planting too late into October. Depending on the planting date, the window for double-cropping soybeans with cotton or corn may be closing if the rains do not come back into the region in a significant fashion.

Models do have a front moving into central Brazil in the Oct. 8-11 time frame that could bring more widespread rainfall. But being so far out, the forecast is uncertain. Should the front disappoint and the showers remain isolated, there could be significant impacts to the start of central Brazil's growing season. The primary risk would be more exposure of the double-cropped corn and cotton to the dry season in 2026, not necessarily to the first-planted soybean crop. This will bear watching in the weeks ahead.

Farther to the south, though, producers from Mato Grosso do Sul to Parana and south through Argentina have had more significant rainfall as systems have regularly come through with swaths of showers. Soil moisture for these areas is much better and planting can go on between rains as they typically do. So far, the dryness concerns have not popped up just yet. But the developing La Nina in the tropical Pacific Ocean threatens hotter and drier conditions during the peak of the growing season that could have some impact later on down the line.

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John Baranick can be reached at john.baranick@dtn.com

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