Corn Silage Drydown Seems Right on Schedule Using Days After Silking

September 23, 2004  11(25):164-165

Joe Lauer, Corn Agronomist

Corn development is quite varied around Wisconsin due to planting date and relative maturity differences. As we enter the fall harvest season, plant moisture will be a key indicator for the harvest management decision to ensure proper fermenting, ensiling, and preserving of corn silage.

Early indications for the 2004 corn silage harvest are that plant moisture seems to be lower than expected using GDU accumulation to schedule harvest.  But, corn silage moisture seems right on schedule using days after silking to project harvest date.

So far, six counties have reported corn silage drydowns (Table 1) with many reporting more than one date. Shorter-season corn planted early is often at the proper moisture, and in some fields, may be past optimum. Corn silage moistures are close to what was projected at the end of July when we knew silking dates of early planted corn. This is in spite of the fact that most Wisconsin counties are reporting a significant lag in GDU accumulation this year, especially during the month of August. Recent dry weather has somewhat confounded corn silage drydown rate, but total growing season precipitation through September is normal at most locations.

We have been tracking two corn fields at Arlington. The same full-season hybrid (105 d RM) was planted either May 5 or May 17. The May 5 planted field is showing some N stress. On September 7, plant moisture in this field was 71.4%, September 10 = 69.5%, September 14 = 63.5% and September 17 = 65.8%. For the May 17 planted field plant moisture was 76.7%, September 10 = 78.2%, September 14 = 78.0% and September 17 = 74.8%. The May 5 planted field had decreased 5.6% and the May 17 planted field has only decreased 1.9%. On September 9, Tom Anderson (Shawano County agent) reported that some fields were drier than they appeared to be.

In summary, plant moisture of fields is quite variable within a county. Early planted fields are drying and developing normally. Special attention should be paid to shorter-season hybrids in early planted fields.

Table 1. 2004 UWEX County corn silage drydown results on September 21, 2004. Results can be downloaded at http://www.cft.uwex.edu/ces/ag/silagedrydown/.
Dane County Silage Moisture (%)   Predicted Harvest Date
Hybrid Relative
Maturity
Planting
Date
Sample
Date
N   Min Average Max   Bunker
/Bag
Concrete
Stave
O2
Limiting
Full-season Early 26-AUG-04 5   80 80 80   Sep 15 Sep 25 Oct 05
Full-season Early 03-SEP-04 6   77 77.8 78   Sep 18 Sep 28 Oct 08
Full-season Early 10-SEP-04 5   75 75.4 76   Sep 20 Sep 30 Oct 10
Full-season Early 14-SEP-04 5   71 72.6 74   Sep 19 Sep 29 Oct 09
Dodge County Silage Moisture (%)   Predicted Harvest Date
Hybrid Relative
Maturity
Planting
Date
Sample
Date
N   Min Average Max   Bunker
/Bag
Concrete
Stave
O2
Limiting
Short-season Late 10-SEP-04 1   80 80 80   Sep 30 Oct 10 Oct 20
Full-season Early 10-SEP-04 8   67 70.5 74   Sep 11 Sep 21 Oct 01
Fond du Lac County Silage Moisture (%)   Predicted Harvest Date
Hybrid Relative
Maturity
Planting
Date
Sample
Date
N   Min Average Max   Bunker
/Bag
Concrete
Stave
O2
Limiting
Full-season Early 31-AUG-04 8   74 75.5 78   Sep 11 Sep 21 Oct 01
Short-season Early 31-AUG-04 3   73 74.3 76   Sep 08 Sep 18 Sep 28
Full-season Late 14-SEP-04 1   80 80 80   Oct 04 Oct 14 Oct 24
Short-season Late 14-SEP-04 4   73 75.2 78   Sep 24 Oct 04 Oct 14
Full-season Early 14-SEP-04 39   61 69.8 75   Sep 14 Sep 23 Oct 03
Short-season Early 14-SEP-04 12   64 68.4 71   Sep 11 Sep 20 Sep 30
Outagamie County Silage Moisture (%)   Predicted Harvest Date
Hybrid Relative
Maturity
Planting
Date
Sample
Date
N   Min Average Max   Bunker
/Bag
Concrete
Stave
O2
Limiting
Short-season Late 09-SEP-04 1   77 77 77   Sep 23 Oct 03 Oct 13
Full-season Early 09-SEP-04 2   65 65.5 66   Aug 31 Sep 10 Sep 20
Full-season Early 13-SEP-04 4   65 67.7 71   Sep 09 Sep 18 Sep 28
Full-season Late 20-SEP-04 3   68 71 75   Sep 22 Oct 02 Oct 12
Short-season Late 20-SEP-04 1   73 73 73   Sep 26 Oct 06 Oct 16
Full-season Early 20-SEP-04 11   60 66.6 70   Sep 14 Sep 23 Oct 03
Short-season Early 20-SEP-04 8   52 62.1 66   Sep 05 Sep 15 Sep 24
Pepin County Silage Moisture (%)   Predicted Harvest Date
Hybrid Relative
Maturity
Planting
Date
Sample
Date
N   Min Average Max   Bunker
/Bag
Concrete
Stave
O2
Limiting
Full-season Late 13-SEP-04 2   66 67 68   Sep 07 Sep 17 Sep 27
Short-season Late 13-SEP-04 8   59 65.8 70   Sep 05 Sep 14 Sep 24
Full-season Early 13-SEP-04 31   62 69 75   Sep 11 Sep 21 Oct 01
Short-season Early 13-SEP-04 13   52 62.0 73   Aug 29 Sep 08 Sep 17
Shawano County Silage Moisture (%)   Predicted Harvest Date
Hybrid Relative
Maturity
Planting
Date
Sample
Date
N   Min Average Max   Bunker
/Bag
Concrete
Stave
O2
Limiting
Full-season Late 09-SEP-04 4   72 75.7 79   Sep 20 Sep 30 Oct 10
Short-season Late 09-SEP-04 1   72 72 72   Sep 13 Sep 23 Oct 03
Short-season Early 09-SEP-04 2   65 67 69   Sep 03 Sep 13 Sep 23
Full-season Late 16-SEP-04 5   64 69.8 74   Sep 16 Sep 25 Oct 05
Full-season Early 16-SEP-04 12   62 67.0 73   Sep 11 Sep 20 Sep 30
Short-season Early 16-SEP-04 3   62 67.3 73   Sep 11 Sep 20 Sep 30

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