South America Calling

Well-Behind-Normal Rainfall

John Baranick
By  John Baranick , DTN Meteorologist
While showers have been active more than the past 60 days for much of South America, amounts have been greatly underachieved. (DTN graphic)

Disappointing is a term that sums up the precipitation situation over much of South America during the past two months. Scattered showers have been around for sure, but amounts and coverage has been less than ideal.

A look at the attached 60-day precipitation anomaly tells the story. Almost everywhere on the continent, and certainly the major growing regions, there has been below-normal rainfall, sometimes dramatically. In fact, according to this modeled output, Mato Grosso and the surrounding area is near or surpassing 300 millimeters (11.8 inches) below normal.

Models have continued to suggest, almost regularly, that widespread heavy precipitation has been likely over central Brazil during the last month or so. While it has been widespread, it has not been heavy. Sure, a few isolated areas will pick up 25-50 mm (1 to 2 inches) in a day's time, but most areas will see roughly half of that. The protocol has continually been to reduce the forecast rainfall amounts by half to get the actual accumulations.

Blame the models or La Nina, but the truth remains: precipitation has not been as abundant as we would expect this growing season.

To say that stress is likely on all corn and soybeans in the region would be an easy point to make, but it does not tell the whole story. As we know, timely moderate rainfall can trump heavy rainfall. A good 1-inch rainfall event every week would make most producers in the U.S. Corn Belt rather satisfied over a 3-inch event with dryness for the following two-to-three weeks. And while Argentina and southern Brazil have seen more periods of dryness, this steadier moderate rain scenario should be true for most of central Brazil.

The almost daily chances at rain should offset at least some of the disappointing rainfall amounts. And while yields may end up to be lower than optimal, I would find it hard to believe that even half of the amount of rainfall will have a disastrous effect on the current season's crop yields, given the frequency of rainfall during the reproductive to early filling stages of the crop.

Satellite images of crop health over Brazil show mixed conditions for most of the region. Interspersed with areas of worse-than-normal crop health are ones with normal to better-than-normal crop health. This may suggest that the frequency of the precipitation has been able to at least limit the overall stress on this season's corn and soybeans.

But that induces a significant caveat, one that we at DTN have been talking about during the last few months. And that is the health of the coming safrinha, or second-season, crop.

With precipitation amounts being less than normal, roughly half during the last two months, the soil moisture profile has not had a chance to fill up for the second season. Recent satellite images confirm that almost the entire country of Brazil, outside of a small area around Sao Paulo, have below- to well-below-normal soil moisture through the soil profile.

La Nina has had a significant impact to the safrinha crop already in that it has pushed the start time back by about two weeks. Couple that with the increased chance that the wet season ends earlier than normal, and producers were looking at a stressful outlook for good-yielding safrinha corn or cotton. Adding in a third pressure of reduced soil moisture to start the season would be another negative factor to a good crop. Should rains end early, the limited subsoil moisture could possibly run out during the reproductive and fill stages of the crop. Eyes should continue to focus on the soil moisture profile going forward as we near the start of the safrinha season next month.

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

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