By Zachary Larson and Brittany Clark
Spring 2020 has been anything but consistent. Only a few weeks ago there were thoughts of an early spring. Cover crops and small grains put on growth and soils began to warm. We even had reports of soil temperatures hitting 50 degrees in in the northwestern part of the state, an event that is not typically seen until May.
But then Mother Nature put the brakes on. Growing degree day (GDD) accumulation came to a halt for nearly two weeks, as shown in the chart of GDD accumulation for State College (figure 1), and the trend turned from being ahead of historical averages to being behind. In many locations, temperatures dipped well below freezing, with some areas receiving a blanket of snow over the weekend. Many areas across the state show a similar trend (table 1).
Figure 1. Growing degree accumulation for State College.
Early crop reports from the USDA – National Agricultural Statistics Service reflect the cooler conditions, with spring oat planting progress about half of where it was at this time last year. The warmup earlier this week sent some famers into the fields and some were planted last week. It takes corn approximately 115 GDDs to emerge, so at this rate of slow GDD accumulation, it will take quite some time to see growing plants in the field.
| Location | GDDs since Jan 1 | Deviation from
15-yr avg. | Precipitation since
Jan 1 (in.) | Deviation from
10-yr avg. (in.) |
|---|
| Franklin Co. | 70 | -40 | 11.3 | -0.1 |
| Lancaster Co. | 56 | -31 | 11.7 | +0.6 |
| Butler Co. | 30 | -28 | 14.3 | +2.0 |
| Columbia Co. | 29 | -37 | 11.6 | +0.8 |
| Cambria Co. | 28 | -23 | 14.2 | +2.8 |
| Crawford Co. | 15 | -34 | 13.4 | +1.0 |
| Bradford Co. | 10 | -17 | 9.61 | -0.4 |
Table 1. Growing degree day and precipitation accumulation as of April 19th for selected locations across the state. GDD calculations were taken from the Cornell Climate Smart Farming GDD Calculator.
While the GDD accumulation trend has been flat for most locations, accumulated GDDs are still within range of long-term averages and a quick warming trend could easily move things the other way. We’re at the beginning of a long season and as this year has already shown, anything is possible.
As reported by local Extension educators, producers in both Franklin and Lancaster counties have planted corn; typically corn requires between 100-120 GDD to emerge.
Source : psu.edu