As the market watches the impact of La Nina on South American crops, Cornbelt farmers should also be watching the potential for lack of subsoil moisture when the 2012 crop is pushing down roots to tap needed water.  Many states are reporting subsoil moisture that is well short of normal as the ground prepares to freeze for the winter and shut out any precipitation.  What can the 2011 La Nina teach us about 2012?

La Nina is the temperature dynamic in the equatorial Pacific which cools or warms the waters that influence temperature and moisture trends across the US, as well as the agricultural areas of Argentina and Brazil.  But while South American crops are suffering from lack of moisture and increasing temperature, what impact will the La Nina have as far as precipitation for the US during the outset of the 2012 growing season.  The Climate Prediction Center of the National Weather Service provides monthly maps of temperature and precipitation, based on La Nina, and its cousin, El Nino.  This Yin and Yang duo currently is pushing temperatures higher across the southern half of the US and pushing precipitation higher into the eastern Cornbelt.  (Noah has already expanded his ark building business throughout Ohio in anticipation of another wet spring.)  However, about planting time and throughout the growing season, the chances for excess precipitation return to even while temperatures remain above normal.

As we approach the early part of 2012, the drought across Texas and Oklahoma and into Kansas is one of the worst agricultural disasters, according to Nebraska State Climatologist Al Dutcher.  While moisture was scarce to non-existent in that part of the country, the eastern Cornbelt was quite wet and caused both planting and harvesting delays, with agronomic problems that included shallow root systems for field crops.  Dutcher says the wet conditions in the fall of 2010 were repeated by La Nina in the fall of 2011 and those will continue into the spring.

On the other hand, the northern and western Cornbelt were dry during the latter part of the growing season into the fall tillage calendar.  That too, was a parallel of the fall of 2010, except for the lack of some heavy rain in southern Minnesota and northern Iowa in 2010 which was not repeated in 2011.  Dutcher says, “A broad area of southern Minnesota, northeastern Nebraska, eastern South Dakota and northwest Iowa has received less than a quarter of normal precipitation during the past 90 days.

One 2011 factor that is not present going into 2012 is the intensity, based on the water temperatures.  It was 3 degrees below normal last year and only 1.5 degrees below normal this year.  We are in a weak La Nina, compared to the strong one of 12 months ago.  Last year the jet stream was also active and winter storm activity was concentrated, but the jet stream has recently split.  That will pull moisture into the northern plains from the Pacific, instead of the Gulf of Mexico.

For the February to April period, below average moisture will occur across the southern tier of states, bulging into the southern Plains.  Above average moisture will occur from the Mississippi River eastward to Ohio.  The Dakotas will have equal chances of above to below normal precipitation.

For the March to May period, above average moisture will remain in the northern tier of states, with below average moisture in the southern Plains and across the Deep South.  Average moisture will occur in the Cornbelt from Iowa and Missouri eastward to Indiana, with above average moisture in Ohio, once again.

Dutcher says the forecast for spring suggests the eastern Cornbelt will remain wet with planting delays and possible flooding in the Ohio and mid-Mississippi River valleys. He says there is currently enough reservoir space to handle normal to slightly above normal snowfall, without major floods, but if snowstorms increase, that could change.

For the second consecutive winter, the Cornbelt has been under the influence of a La Nina, but this current system is not as intense as one year ago.  While significant portions of the western Cornbelt are entering the winter with subsoil moisture at relative low levels, some recharge may be forthcoming.  The eastern Cornbelt will remain wet again in the spring of 2012, with potential for more planting delays and flooding.

Source: FarmGate blog