With below-average sea temperatures beginning to warm, La Niña peaked in mid-February. It’s transitioning toward ENSO-neutral conditions during March through May 2012, according to National Oceanic and Atmospheric Administration (NOAA) officials.
"The big debate right now is how much of a lingering La Niña footprint will remain through the spring planting season," says Drew Lerner, who has forecasted crop weather for 30 years as owner of World Weather, Inc. "There's a high probability that La Niña will still be with us through at least the first half of spring, with a footprint into the second half."
Traditionally, the presence of La Niña or its footprintmeans an increased chance for above-average temperatures across the south-central and southeastern U.S., and below-average temperatures in the northwest for the March through April time period. Precipitation will be above average across the northern tier of states (except in the dry north-central U.S.) and in the Ohio and Tennessee valleys. Drier-than-average conditions are more likely across the southern U.S., according to the mid-February NOAA Weather and Crop Bulletin.
Lerner says there's a tremendous amount of North America that is already dry – from Canada down across the northern Plains and Upper Midwest; also from the west through the southern Plains into the southeastern U.S. "It's not normal to miss out on precipitation during the winter months like we have, which depletes the moisture reserves in these areas," Lerner says.
Not only is there very little snow cover across the Midwest; the snowpack in the Rocky Mountains has yet to reach an average year. "We're nowhere close to the flooding potential we witnessed last year on the Mississippi and Missouri rivers," Lerner says. “We may see some short-term minor flooding possibilities in the Ohio River basin and the Delta due to wetter soils, but we expect the crops to get planted in a fairly timely fashion.
"Currently, it appears we might be dependent on timely rains to produce good crops in the northern Plains and the western Corn Belt. There's no doubt the Upper Midwest will have a drier than normal spring because it is lacking moisture already," Lerner says.
At the end of the fourth-warmest and 28th-driest January on record since 1895, NOAA reports 31% of the U.S. is under moderate to extreme drought, and 14% falls into the severely to extremely wet categories. (For details, see State of the Climate (www.ncdc.noaa.gov/sotc/drought/.)
"I still have a drier bias in the forecast," Lerner says. "If we can totally lose La Niña with no lingering footprint left, which is a big 'if' right now, then there is potential for timely summer rains. As spring goes along and a high-pressure ridge builds in the central U.S., it should spread rainfall potential in the western Corn Belt."
This weaker La Niña will bring some good news to the parched Texas, Oklahoma and the Delta areas in the form of good precipitation, according to Lerner. "These areas will see above-normal precipitation in March and April, which will slow planting, yet still allow the crops to be planted on a timely basis. The hydrologic drought (river/stream flows, reservoir levels, ground water table) will still prevail through the growing season, but the soil moisture will help get the crop off to a good start. The southern Plains will dry out in June and July, but nothing as serious as last year," he adds.
Regarding heat, Lerner says any time you have a drier bias with a high-pressure ridge in the crosshairs for late spring, you run the risk of it getting pretty warm. "For the eastern Midwest, from Michigan and Indiana into Ohio and down through the Carolinas, we should see a fairly mild summer – not excessively hot. The farther west you go, the warmer it will be," he adds.
We'll see some stress and some problems during the spring, but the odds are against any major problems, Lerner says. "The really severe wind and hail events from last year won't be repeated this year, because that was the product of a very strong La Niña. We will still have some wild weather, but nothing like 2011."
*Field drainage. Poorly drained soils can hinder the establishment of vigorous corn stands by challenging the uniformity of roots and plant development. Improving tile or surface drainage reduces the risks of ponding or soggy soils, denitrification and soil compaction.
*Soil erosion control and soil moisture conservation. In areas of rolling hills with high risks of soil erosion and reduced ability to retain soil moisture, Bob Nielsen, Purdue University Extension agronomist, says it is important to minimize water runoff and maximize soil moisture retention. Some techniques include no-tillor reduced tillage, strip-cropping, contour farming, terraces and other water control structures and fall and winter cover crops.
*Hybrid selection. "The key challenge is to identify hybridsthat not only have good yield potential but that also tolerate a wide range of growing conditions," Nielsen says. "The best way to accomplish this is to evaluate hybrid performance across a lot of locations. University trials are good for this exercise."
Nitrogen management. Because the eastern Corn Belt has poorly drained soils, ample rainfall and the risk of nitrogen (N) loss by either denitrification or leaching, growers need to pay special attention to N management. According to Nielsen, best management practices include avoiding fall applications, avoiding surface application of urea-based fertilizers without incorporation and adopting sidedress N application programs where practical.
Disease Management. Warm, humid summer weather conditions in the eastern Corn Belt are ideal for the development of many corn diseases, such as gray leaf spot and Northern corn leaf blight. The best ways to manage these diseases are selecting hybrids for strong disease-resistance characteristics, avoiding continuous-corn cropping systems, avoiding no-till cropping systems and responsibly using foliar fungicides.
Finally, Nielsen says, producers need to "remember it ain't rocket science."
"We're talking about a lot of common-sense agronomic principles that work together to minimize the usual crop stresses that occur every year and allow the crop to better tolerate uncontrollable weather stresses," he says.
Source: Bob Nielsen, Purdue University Extension agronomist.