Lack of sun in southern Brazil soy states hurts yields

Wet, cloudy weather is dragging down soybean yields in Brazil’s second largest soybean producing state of Parana, local farmers, cooperatives and officials have said.

Brazil is coming off a record 2016/17 soybean harvest of 114 million mt that was aided by near perfect weather nationally.

However, after irregular rains delayed the start of planting of the current crop in late 2017, most forecasts projected a drop in yields for the 2017/18 harvest.

In Parana, which last year produced 18 million mt of beans, or 16% of the total crop, overcast skies and heavy rain have set in since the New Year.

And agronomists say the lack of sun and photosynthesis is so significant in some areas that it is sapping the crop’s ability to fill pods.

“Although some producers’ crops look great… some problems with pod filling have been showing up,” said Edmilson Zabat, vice president of the farming association in Palotina in western Parana state.

He said that some of the plants’ pods are not filling or some will only fill one or two beans instead of the typical three beans, or simply aborting pods altogether for lack of enough sunlight.

Brazil’s crop research department Embrapa said solar radiation levels it tracks in some soybean producing regions of the state have fallen by 15% from average levels because of more frequent cloud cover since the season began September.

“Studies show that lower levels of luminosity in the reproductive phase of the plant can reduce yields in soybeans by 17% to 26%,” Embrapa researcher Rodrigo Arroyo Garcia said.

Coopavel, one of Brazil’s largest southern farming cooperatives, reported earlier this week that initial yields from early harvesting in its area of influence were down nearly 4% compared to last season.

Most agronomists warn that it is still too early to make an accurate estimate of average yields as the harvest is just beginning in some areas.

In Brazil’s center-west soy belt, farmers are reporting better than expected yields, comparable to last season’s record levels, but recent heavy rainfall and flooding in areas have become a concern as well.

Famers say they have not been able to enter some fields to harvest them because of wet soil that turns to mud.

On Tuesday, private analysts Cordonnier and Rabobank downgraded their expectation of Brazil’s soybean output.