The expected development of a moderate La Nina could result in prolonged dryness and warmer temperatures across some of the largest grain producing countries globally, according to Kyle Tapley, senior agricultural meteorologist with weather agency Maxar.
During a Sept.17 webinar, Tapley said the countries most likely to be impacted are Argentina, Brazil and Ukraine, along with parts of the US and Russia.
The US, Brazil, Argentina, Ukraine and Russia are among the top producers and exporters of corn, soybean and wheat globally.
The US National Oceanic and Atmospheric Administration and the United Nations' World Meteorological Organization both say there is a possibility of a moderate La Nina event between September and November.
However, Tapley said the probability of a stronger La Nina event has increased over the last few weeks.
The La Nina phenomenon, which is an occasional but natural cooling of the equatorial Pacific, can results in weather changes worldwide.
Generally, Southeast Asia, South Africa, India and Australia receive above-normal rainfall in event of a La Nina event, and drier weather is seen in Argentina, Europe, Brazil and southern US, Tapley said.
"Typically we see global corn and soybean yield decline during a La Nina year because it results in dryness in North and South America," he added.
Dryness in the US
Dryness in the world's largest corn producer — the US — would likely result in a reduction of the yield from the planted corn crop. The US Department of Agriculture cut its corn yields estimate to 178.5 bushel/acre earlier in September from record high estimate of 181.8 bu/acre in August.
Drought-like conditions developed in the major corn growing regions in the US during August, and conditions are likely to be dry in the coming days as well, said Tapley.
The continued dryness will lead to a decline in soil moisture again in parts of Midwest and it may cause stress to late planted soybeans, he said. However, the corn crop has reached maturity so it is unlikely to have any further impact on corn yields, he added.
For the next three months, rainfall is expected to be below normal in the southern US, which is likely to raise concerns of a soil moisture deficit for the start of the spring planting season in March 2021, said Tapley.
Tapley said that if La Nina continues until March, it will be a major cause of concern.
Black Sea, Europe
"The biggest worry area globally right now is the Black Sea region, as it is very dry there," said Tapley, adding that widespread dryness in Ukraine and southern Russia is likely to continue for the next 15 days.
Ukraine and Russia are major producers and exporters of corn and wheat, and dryness in the countries has impacted yields of both grains adversely in the past of couple weeks.
On Sept. 10, S&P Global Platts Analytics lowered its corn production estimate for Ukraine due to dry weather in parts of the country.
In southern Russia, a forecast of dry weather for the next 10-15 days is likely to slow germination and early development of recently planted winter grains, Platts Analytics added.
Across top wheat exporter Europe, temperatures are likely to be warmer than normal for the next two to three months, according to Tapley.
Wheat production in the EU is set to decline on the year due to unfavorable weather in France, Germany, the UK, Romania and Bulgaria, according to Platts Analytics.
South America
Tapley said that over the next two or three months, the largest area of concern will be damage to Argentina's production of corn, soybeans and wheat.
Dry weather that returned last week is likely to continue for at least another week in Argentina, Tapley said.
During the Southern Hemisphere summer months — December to February — Argentina is likely to witness above-normal temperatures, along with below-normal rainfall, Tapley said, adding that the patterns can be extended to southern Brazil in the event of a stronger La Nina.
In Brazil — the second largest exporter of corn globally — the planting of the first corn crop for the 2020-21 season started in the week that ended Sept. 11.
Below-normal rainfall has resulted in soil moisture deficits in parts of Brazil. Though some rains are expected in Brazil in the coming days, it is still not going to be enough to dramatically replenish soil moisture, said Tapley.
"Overall, for South American crops, particularly Argentina, corn and soybean will probably see some issues due to the dryness," he said.
