|
Colby, Kansas | Ed, we haven't talked in a while, hope things are well for you, other than being dry. I must admit when I saw the title of your post I thought "These guys have no idea what dryland corn is" but I must admit 5" is perty extreme even by high plains standards. In the chart below, almost 80% of our seasons will have greater than 5" precipitation.
What are your soils like there, our Keith/Holdrege/Colby/Ulysses type silt loam soils typically have a plant available water of around 0.21% or 15.12" in a 6 ft profile. Thats a lot of storage for a region that gets 16-22 inches annually so we don't start with a full profile very often, however having some water in the profile is critical.
Our yield goal is typically 80-100 bu. A lot of times when we are under water stress we are also under heat stress and thus we tend to have some pollination train wrecks.
Any idea what type of profile water you started with? If you had good profile water to start and made it through pollination, you may be very surprised to see how far 5 inches will go.
I'm actually been working tonight on some rainfall probability vs. yield stuff. I have the daily weather data for McCook, NE from 1906-2006. If you want something that will tickle your brain a bit I would recommend getting the dataset for your area. The best corn year I can remember is 1998, the first year I sold seed, my dryland test plot went 158 bu. I estimate we had moisture of the following available to the crop:
3 July 97 - 15 November 97 (Fallow Period from Wheat Harvest to Beginning of Winter Precip Period)
14.02" x 21% fallow storage efficiency = 2.944"
15 November 97 - 31 March 98 (Winter Fallow Period - Includes Rain and Precip Equivalent of Snow)
14.85" x 80% fallow storage efficiency = 11.88"
1 April 98 - 15 May 98 (Preplant Fallow Period)
1.3" x 21% fallow storage efficiency = 0.273
TOTAL ESTIMATED SOIL WATER AT PLANTING = 15.097" Basically we started with a full profile.
15 May - 31 August Precip = 8.4" (3.17" came in events that were < 0.30")
If we completely emptied the profile that figures a water use efficiency of a little over 6 bu/in. Not spectacular but not unbelievable either.... I'm betting that we didn't empty the profile of water,, I think we reached our maximum yield potential with inputs 80# of N and 15,000 population.
I'm betting that our 8" of in-season is similar to your 5" of in-season. We receive a lot of summer precip in 0.20 0.30 type increments, those are basically worthless because of our high evaporation rates.
Sorry for the long rambling post, but I think what I'm trying to say is, if you started with a full profile and made it through pollination, I think 140 is not out of the realm of possibilities.
Regards,
Lucas
Edited by LHaag 8/4/2007 00:18
 (McCookPrecipProbability.JPG)
Attachments
----------------
 McCookPrecipProbability.JPG (33KB - 75 downloads)
| |
|
Dryland corn farmers
