Argentine Rains A Game Changer For Soybeans

02/02/11 -- Reproduced by kind permission of my chums at the excellent Martell Crop Projections:

Drenching January rainfall in Argentina significantly improves the outlook for late planted soybeans that fill pods in February-March. It was enough rain to completely restore topsoil moisture. The January rainfall map now is wetter than normal in Cordoba and Santa Fe, key soybean provinces, following 4-5 inches of rainfall last weekend.

The recuperative powers of soybeans are well documented in the United States Midwest. If heavy rain arrives in time for pod setting and filling, soybean yields increase even if very dry conditions existed previously. Pod setting and filling is the period when yields are made or lost. Very heavy rain increases both the number and size of soybeans in the pod. In the Midwest this critical stage is in August. For Argentina February-March is the rain-sensitive period.

Included in this report (you'll have to subscribe using the link above if you want to see it - Nogger) is proof of Iowa soybeans responding to heavy late-summer rain, while corn floundered. The year was 1977. Conditions had been extremely dry May- July, damaging corn beyond repair. The corn yield finished 11% below trend. Soybeans rebounded making a productive yield 3% above trend. August rainfall was 7.8 inches and 195% of normal.

Slower than normal Argentina soybean planting rates may prove to be a blessing. Forty percent of beans were sown after December 1, based on Ministry and Agriculture reports. These late planted soybeans would bloom in February. Pods are “set” 10-12 days after blooms develop. This is followed by 30-40 days of seed filling. The message: There is still a lot of time left for late developing soybeans to improve, if heavy rain continues.

Drenching rainfall is Cordoba and Santa Fe over the weekend was preceded by drought-breaking rainfall in Buenos Aires province two weeks prior. We get the impression the weather pattern is changing. The sudden changeover toward wetness may be linked to a weakening La Nina. Drought is very typical with La Nina in Argentina. This country is one of the more sensitive areas where weather responds strongly the ENSO fluctuation. Last year with El Nino, conditions were extremely wet, causing concerns over disease in soybeans.

Warming sea temperatures developed at the same time in the sentinel eastern tropical Pacific Ocean, signifying a weakening La Nina. What we do not know is whether this is a short-term fluctuation or the beginning of La Nina’s demise. The Australia Bureau of Meteorology suggests the La Nina may continue throughout calendar year 2011. Should this be the case drought may resume in the Argentina grain belt.