Soil temperature, seed germination and the unusual spring of 2012
How do soil temperatures for 2012 spring planting compare with previous years?
Crop seeds (and potato seed pieces) germinate and grow based, at least partially, on soil temperatures. Seed will remain dormant until the minimum soil temperature for germination is reached. The seed germination process will be slow at or near the minimum soil temperature, compared to a more favorable, or optimum, soil temperature for germination. If seed germination is delayed by cold soil temperatures, pathogens including root rots and damping-off organisms have a better chance of infecting the seedling, increasing the likelihood of significant stand thinning and overall yield reduction.
There are big differences between “minimum soil temperature for germination” and “optimum soil temperature for germination.” These soil temperatures are good to know, and should be considered as useful factors to determine seeding date along with frost-free dates and typical growing season limitations. However, the realities of time management on the farm can often result in compromising what we’d like to do with what we need to accomplish. In other words, farmers try to be as timely as possible with planting dates.
Along with the big difference between minimum and optimum soil temperature for germination, there is also some variation between information sources about the soil temperatures for specific crops. Listings from university and governmental sources in Nebraska, Alberta, Canada and other locations were used to prepare the following unofficial table.
Soil temperatures for germination of selected crops
Crop |
Minimum (°F) |
Optimum (°F) |
Barley |
40 |
68 |
Oats |
43 |
68 |
Canola |
50 |
60 |
Alfalfa |
48 |
77 |
Birdsfoot trefoil |
45 |
79 |
Red clover |
45 |
77 |
Orchardgrass |
40 |
65 |
Timothy |
40 |
65 |
Field corn |
46 |
86 |
Pumpkin |
60 |
85 |
Potato |
45 |
65 |
Soybean |
50 |
77 |
Dry bean |
60 |
80 |
So, where are we currently with soil temperatures in Michigan? Has the early warm-up in March affected planting dates, and if so, how much? How do soil temperatures this year compare with previous years?
The MSU Enviro-weather program is a good place to look for answers to these important questions on a local or regional basis. Simply click on a weather station location on the state map near, or comparable, to your farm. This will take you to the webpage for that weather station with weather summaries and degree day tools for that location. From there, you can view tables under “Soil Conditions” giving daily soil temperature reports over your selected time period. You can also view growing degree day (GDD) accumulations and prepared GDD tools including GDD comparisons over the last five years and GDD accumulations specifically related to alfalfa and corn development. (The GDD base 42 tool is very useful for planning first alfalfa cutting – 750 GDD for alfalfa placed in vertical silo storage, 680 GDD for alfalfa placed in horizontal silo storage). You can also access the Alfalfa First Cutting tool by selecting “field crops” from the horizontal list at the top of the screen, then clicking on the folder next to “Alfalfa.”
Example of Ithaca soil conditions
2012 |
Air
Temperature |
Soil
Temperatures at 2 inches |
Soil
Temperatures at 4 inches |
Rainfall (in.) |
Soil moisture (in./in.) at 4 inches |
Soil moisture (in./in.) at 10 inches | |||||||
Day |
Date |
Max |
Min |
Max |
Min |
Max |
Min |
Today |
Since 4/15 |
Max |
Min |
Max |
Min |
Sun |
4/15 |
72.3 |
55.5 |
59.3 |
52.9 |
57 |
52.3 |
0.48 |
0.48 |
0.245 |
0.21 |
0.366 |
0.364 |
Mon |
4/16 |
67.6 |
38.8 |
58.6 |
49.6 |
57.7 |
51.5 |
0.51 |
0.99 |
0.278 |
0.236 |
0.451 |
0.366 |
Tue |
4/17 |
55.1 |
33.7 |
54.4 |
45.1 |
53.1 |
47.1 |
0 |
0.99 |
0.267 |
0.253 |
0.398 |
0.39 |
Wed |
4/18 |
65.3 |
32.3 |
54 |
44.5 |
52.6 |
46.5 |
0 |
0.99 |
0.257 |
0.244 |
0.39 |
0.387 |
Thu |
4/19 |
63.3 |
43.2 |
57.2 |
49 |
54.8 |
49.6 |
0.04 |
1.03 |
0.248 |
0.239 |
0.387 |
0.385 |
Fri |
4/20 |
46.3 |
37.5 |
52.2 |
45.4 |
52.6 |
46.8 |
0.53 |
1.56 |
0.295 |
0.236 |
0.468 |
0.385 |
Sat |
4/21 |
49.8 |
32.1 |
51.8 |
42.1 |
50.2 |
44.1 |
0 |
1.56 |
0.296 |
0.281 |
0.466 |
0.399 |
Sun |
4/22 |
51.2 |
30.9 |
48.7 |
41.7 |
48.1 |
43.8 |
0 |
1.56 |
0.287 |
0.272 |
0.399 |
0.392 |
Mon |
4/23 |
58.5 |
34.2 |
50.8 |
40.8 |
49.3 |
43 |
0 |
1.56 |
0.277 |
0.26 |
0.392 |
0.387 |
Tue |
4/24 |
60.3 |
38.6 |
51.2 |
42.4 |
49.6 |
43.7 |
0 |
1.56 |
0.265 |
0.248 |
0.387 |
0.384 |
Wed |
4/25 |
64.4 |
33.6 |
54.5 |
43.1 |
52 |
44.7 |
0 |
1.56 |
0.253 |
0.242 |
0.384 |
0.382 |
Thu |
4/26 |
55.2 |
35.7 |
52.6 |
46.9 |
51.3 |
48.4 |
0.02 |
1.58 |
0.245 |
0.238 |
0.383 |
0.382 |
Fri |
4/27 |
57 |
28.3 |
53.8 |
42.4 |
51.6 |
44.4 |
0 |
1.58 |
0.243 |
0.229 |
0.382 |
0.379 |
Sat |
4/28 |
48.4 |
34 |
49.5 |
44.9 |
49.5 |
46 |
0 |
1.58 |
0.233 |
0.224 |
0.379 |
0.377 |
Sun |
4/29 |
61.1 |
27.8 |
54.3 |
41.5 |
51.8 |
43.5 |
0 |
1.58 |
0.226 |
0.217 |
0.377 |
0.375 |
Mon |
4/30 |
51.7 |
38.8 |
50.6 |
46.6 |
49.9 |
47.3 |
0.35 |
1.93 |
0.245 |
0.217 |
0.375 |
0.375 |
Tue |
5/1 |
54.9 |
45.9 |
53.3 |
48.7 |
52.1 |
48.9 |
0.01 |
1.94 |
0.244 |
0.235 |
0.375 |
0.375 |
Ithaca Historical Degree Day Summary (Numerical Integration method) from
3/1/2012 to 5/2/2012
Year |
Degree Days Base 42°F |
Degree Days Base 45°F |
Degree Days Base 50°F |
Dates evaluated |
2007 |
342 |
261 |
162 |
Data from 3/1 through 5/2/2007. |
2008 |
62 |
48 |
30 |
Data from 3/1 through 5/2/2008. |
2009 |
281 |
205 |
115 |
Data from 3/1 through 5/2/2009. |
2010 |
477 |
375 |
242 |
Data from 3/1 through 5/2/2010. |
2011 |
211 |
154 |
87 |
Data from 3/1 through 5/2/2011. |
2012 |
532 |
422 |
268 |
Current data from 3/1 through5/2/2012 3PM. |
Average of 4 years, not including current year |
327.9 |
248.8 |
151.5 |
4 years with > 90% of data. |
For more information, contact Jim Isleib, U.P. crop production educator,
at 906-387-2530.