Beneficial rains for Argentina’s soyabeans do not cancel La Nina risks

FORT COLLINS, (Colo.): Argentina’s core grain belt is on pace for better rainfall this month than has been seen in many recent Novembers, but with La Nina in action and planting still in progress, the country’s soyabean crop remains at risk of a third consecutive disappointment.

February and March are usually the most important weather months for optimal yields in Argentina, though rainfall through the planting period also correlates well with crop potential, so comfort levels would increase if next month’s rainfall can follow November’s showing.

As of Thursday, Argentina’s soyabeans were 32% planted, about the same as both last year and the recent average. The country’s soyabean planting dates have been very reliable since the progress has barely fluctuated in the last several years, and sowing should be nearing 90% complete by the end of December.

The probability of truly good soyabean yields in Argentina is only one in 10 during a La Nina, which happens when surface waters in the equatorial Pacific Ocean are cooler than normal. The phenomenon occurred last year, too, and the country’s soyabean and corn yield fell short but avoided total disaster.

Based on data from the past three decades, Argentina’s soya areas have a one in five chance of normal or above normal rainfall in December when La Nina is as strong or stronger than it has recently been.

La Nina is linked with drier weather for Argentina’s summer growing season, but it is inaccurate to say that rainfall cannot be normal or even above if the cool phase is present. The better way to describe it is to say that most of Argentina’s driest years coincided with La Nina’s presence.

The good news is that global climate predictions, both numerical and human-judged, see La Nina potentially fading faster than last year in the early months of 2022. That could allow for rainier conditions during Argentina’s critical period.

The latest readings across the Pacific Ocean’s surface show that the waters have reached their coolest overall levels in nine months and the current strength is comparable with a year ago.

Last month, the top layer of equatorial ocean waters notched their coolest anomalies in 11 years, which had triggered the historically strong 2010-11 La Nina. Argentina’s soya and corn yields were poor that year but nowhere near as bad as during the comparably weaker La Nina of 2017-18.