D. Comparison of the 2015 Average to the 2014, 2013 and 4YA
2015 was cool, like 2014, but had more early rainfall, with almost-record yields.
While both 2014 and 2015 had less-than-average planting in April, producers in 2015 planted a full week ahead of the 4YA in the first half of May. Abundant rains, along with cooler than average temperatures, then came in June and July of 2015, delaying vegetative growth and silking/pollination to a week behind the 4YA. The vegetative growth rate and silking time of 2014 was similar to the 4YA, in contrast to the delayed development in 2013. Similar to 2014, the rains moderated in a majority of the corn-growing region in 2015, allowing for a greater than average number of kernels to be pollinated, establishing the potential for high yields in those field areas that did not suffer from excess water.
During the grain development stage, both 2014 and 2015 were cooler than the 4YA. There was a temporary drought and heat stress in 2013, whereas 2014 had ample rain and more soil moisture, and 2015 had early rains that became widely scattered by summer. Harvest in 2015 had a slow start but quickly surpassed the 4YA, in contrast to both 2014 and 2013, which trailed the 4YA by multiple weeks of rain and freezing temperatures.
Throughout much of 2015, the corn crop had a near 70% Good or Excellent condition rating, signifying good plant health, leading to greater photosynthesis, starch accumulation, and yield.2 This high rating was only slightly less than in 2014, which had record yield. In contrast, poorer growing conditions in 2011 through 2013 are reflected in the decreased 4YA condition rating compared to 2014 and 2015. The corn crop in 2013 was less healthy than 2014 and 2015 due to heat and a short but intense drought during grain development that year.
2A “Good” rating means that yield prospects are normal. Moisture levels are adequate and disease, insect damage, and weed pressures are
minor. An “Excellent” rating means that yield prospects are above normal, and the crop is experiencing little or no stress. Disease, insect damage,
and weed pressures are insignificant.