The recent run of chilly temperatures in much of the country makes the following comments on the impact of climate change for Nebraska agriculture by Nebraska state climatologist Al Dutcher worth a read. The message here is that climate change effects on conditions for springtime are not equal--and an out-of-balance relationship between air temperature and soil temperature mean that early planting is not a guarantee. These comments are from a report by the Institute of Agriculture and Natural Resources, University of Nebraska-Lincoln.--Bryce
"Research conducted by the High Plains Regional Climate Center has found that the date when 4-inch soil temperatures under bare soil are occurring is nearly two weeks earlier than in the early 1980s. What little moisture might be gained during the winter months in a warming environment would be lost to increased evapotranspiration from vegetation that breaks dormancy earlier in the year.
By the year 2100, the National Climate Assessment report indicates that the frost-free season will increase by 30 to 40 days for Nebraska. A shift to earlier planting dates will only be effective if the spread of the distribution curve remains consistent. Vulnerability to freeze damage would increase if the mean freeze date shifts earlier into the year, but the distribution does not shift by an equal proportion. This is a critical issue for producers, as the 2012, 2013, and 2014 growing seasons produced hard freeze conditions during the first half of May, even as favorable soil temperatures are occurring two weeks earlier when compared to the early 1980s.
If precipitation amounts remain steady or decrease by the year 2100, evapotranspiration demand will result in less moisture available to growing crops during their critical reproductive periods that occur in May (wheat), July (corn), and August (sorghum, soybean). During 2012, native vegetation broke dormancy a month earlier than normal and soil moisture reserves were depleted across most of the U.S. Corn Belt well before the critical pollination period was reached.
There is a general thought that as the climate warms, crop planting dates can be shifted earlier in the year, thus decreasing the likelihood that plants will come into reproduction during the statistical peak of the summer heat. The drought of 2012 proved this theory invalid when precipitation was insufficient to keep plants out of perpetual water stress conditions."
A final note--while the details in these comments were focused on Nebraska, the disparity between soil warming patterns and air temperature patterns is likely in effect in other states across the central U.S.--BA
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