(Adds weather report from Buenos Aires grains exchange, Rosario exchange estimate on impact to farmers' incomes)
By Maximilian Heath
BUENOS AIRES, Jan 13 (Reuters) - Carlos Boffini, an Argentine grains farmer from Colón in the north of Buenos Aires province, is praying for rain amid an extended drought and heat wave that has hammered the country's soy and corn harvest outlook.
The major Rosario grains exchange on Wednesday slashed its forecast for 2021/22 corn production to 48 million tonnes, down a huge 8 million tonnes from its previous outlook, scuppering what had been expected to be a record harvest.
The exchange also cut soybean production to 40 million tonnes from 45 million tonnes previously, and said that the drought so far had caused an estimated $2.9 billion hit to grains farmers' expected incomes.
"The early corn has been battered. The sun is fierce, it is seven in the evening and it continues to burn you," said Boffini. "Fifty percent (of early corn) was lost. Soy is holding out a bit longer, but it needs water."
Argentina, the world's top exporter of processed soy and the no. 2 producer of corn, is going through a prolonged dry spell linked to the La Nina climate pattern which usually leads to lower rainfall in central parts of the country's farm belt.
A major heat wave with temperatures rising as high as around 45 degrees Celsius (113°F) in some areas has further compounded the period of low rainfall, scorching crops in key stages of development and hurting yields.
"The water stress in December has slowed down growth, causing flower abortion, leaf burning, seedling death in the most affected areas and some planting in fields starting to be abandoned," the Rosario exchange said in a crop report.
The exchange added that later-sown corn would rely on rains arriving, although those could be delayed until March towards the end of the southern hemisphere summer.
"The rains stopped from late December. Christmas passed and it did not rain, New Year came and it did not rain, and it still does not rain," Boffini said.
"At night it does not cool down and the crops are not oxygenated. This whole area is very complicated."
'RAINS ARE COMING'
Germán Heinzenknecht, meteorologist at the Applied Climatology Consultancy (CCA), was more optimistic. He said that from Sunday the temperature would drop and that some rains would arrive, which could help temper the losses crops faced.
"The volume of rainfall is going to be uneven, we can hope for between 30-40 millimeters in the core agricultural areas, with some areas that could see double these figures," he said.
"The amount of water is though going to fall short of what the fields need. You will not have a full recovery, but we hope that after this event we will enter a process of recovery of the level of rainfall, with a loss of the La Niña effect."
He said early corn had suffered heavy losses, but soybeans could get a reprieve if the coming rainfall lasted.
"This could be a pivotal event for the campaign," he said. "The rains are coming. We still can't say it's a disaster."
The Buenos Aires grains exchange said in a report https://www.bolsadecereales.com/imagenes/informe_climatico/2022-01/540-perspectivasagroclimatica13.01.pdf on Thursday that it expected rains of "varied intensity" next week, focused on the central area of Argentina, while there would be "moderate to abundant" rainfall in the following period.
For now, Boffini can only look to the skies.
"Let's see how much it rains, because with 15-20 millimeters, the next day it is as if nothing happened," said Boffini. "You have to watch and hope that at least you do not continue to lose more."
(Reporting by Maximilian Heath Editing by Adam Jourdan, Alexandra Hudson and Frances Kerry)
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