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Post by happyskunk on Apr 23, 2011 11:01:03 GMT -5
Hi Joseph, In your example above of 50F + 108F you calculated 29 growing degree days. From what I have seen most set a max of 86F for corn. They say corn does not grow more above 86F. So using the same formula ([(Tmin + Tmax)/2] - 50) but with a max of 86F the growing degree days would be 18 for that day. I'm not sure, temps as high as 108 might even have a negative effect on corn growth? As temps get higher maybe we should be subtracting from GDD? One internet site I was looking at even said that high night-time temps negatively affect corn growth.
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Post by Joseph Lofthouse on Apr 23, 2011 13:36:08 GMT -5
Too much math for me...
If I have a 108 degree day here, it's only above 86F for a few hours: Most of the day it would be somewhere between the high temperature and the low temperature. We could take hour by hour readings and integrate them (a math term), but I'm guessing that taking an average between the high and the low temperature gives almost the same results when considered over a growing season.
In my garden I sure don't have to worry about the few hours a growing season that it's over 86F, or about it being warm at night.
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Post by keen101 (Biolumo / Andrew B.) on Apr 23, 2011 15:50:26 GMT -5
Okay i used the weather data from that website and found how to access the precipitation data. I decided to graph it so i could compare it to my other graph. I can see how graphing data like this can be helpful. The first graph is useful to me because it shows me how long my growing season is. When combined it seems like it is easy to guess which spikes are the spring snowstorms which is also very useful. But how are the actual GDD calculations helpful? Are they a way to replace day's to maturity by calculating how fast corn will actually grow? Maybe i'm the only one confused as i've never really used day's to maturity anyway. Michel lives in Canada, so i can see why he would want to keep track of this data. Especially in light of changing climate conditions. Michel i hope you are able to figure all this out!
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Post by Joseph Lofthouse on Apr 23, 2011 16:39:46 GMT -5
But how are the actual GDD calculations helpful? Are they a way to replace day's to maturity by calculating how fast corn will actually grow? GDD may be more helpful to me than the days-to-maturity listed on a seed packet, because days-to-maturity is a totally bogus number in my garden because my climate is so radically different than the typical growing season. (75 day tomatoes take 95 days in my garden.)
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Post by keen101 (Biolumo / Andrew B.) on Apr 23, 2011 17:49:27 GMT -5
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Post by 12540dumont on Apr 25, 2011 14:38:07 GMT -5
users.gmavt.net/lcfarm/sweetcorn.htm#nI have found this chart to be very useful when waiting to plant another corn. Last year my 68 day corn took 88 days. Nothing worse than have 3 varieties of corn all on the same day. It's too much corn and then there's none. Today I'm planting 4 kinds of corn. Texas Gourdseed, Santa Domingo Posole, Augusta, and Trinity. It's the next batch I have to watch out for. Gone are the days when I could just tick off 14 days and plant another batch for wave after wave of glorious corn. I can't wait for you to add San Martin, CA to your graph! Always helpful this forum
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Post by spacecase0 on Apr 25, 2011 18:37:31 GMT -5
so then how do you calculate days that the low is over 86F ? if you had a 110F high and an 86F low does that mean that the most heat units you can get in a day is 36 ? or would 48 be possible ? or should I just store raw data, calculate with corn grown in 2 locations and see then what formula matches ? maybe the heat only matters when the corn has sun on the leaves ? or is this pointless complication ?
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Post by happyskunk on Apr 25, 2011 20:57:12 GMT -5
This is fun! 2010 Cumulative GDD 10C base
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Post by Joseph Lofthouse on Apr 25, 2011 21:15:48 GMT -5
This is fun! 2010 Cumulative GDD 10C base Ha! No discussion of corn breeding is thorough unless Oaxaca Mexico is included!!! We had a heavy thunderstorm overnight, but it completely missed one of my fields so today I tilled, then planted potatoes until about 6PM when a thunderstorm hit that field. (This is the first day it has technically been dry enough to till, though I have tilled a little bit here and there already in too wet soil.) If it had held off a few more hours I would have planted Painted Mountain flour corn and popcorn. But with the soil tilled now I can easily get those in despite the current rain. I'm glad to be having fun by proxy!
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Post by DarJones on Apr 26, 2011 0:08:03 GMT -5
mudslogging Joseph?
I planted Pennsylvania Butter Flavored popcorn today and will start some Buhl sweet corn in trays tomorrow. I have plans for a late crop of sweet corn to continue with the breeding from last year.
Re the charts, Jacksonville NC is closest to my climate here in Hamilton, AL.
DarJones
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Post by Joseph Lofthouse on Apr 26, 2011 0:33:33 GMT -5
mudslogging Joseph? I planted Pennsylvania Butter Flavored popcorn today and will start some Buhl sweet corn in trays tomorrow. I have plans for a late crop of sweet corn to continue with the breeding from last year. Oh my gosh! The mud this year never ends. Usually we get a few dry days in a row so we can plant... Our grain farmers are weeks behind on plowing this spring. I'm wondering about planting some corn from Oaxaca in trays, since it was way long season for my garden last summer (or had day-length issues). How early should I plant them? How big of pots do you recommend? Any other recommendations?
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Post by 12540dumont on Apr 26, 2011 18:28:25 GMT -5
Thanks Happy Skunk...Finally a chart for San Martin. And boy do I need it.
Is there anything as much as a headache...oww the math...as corn?
Holly
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Post by 12540dumont on Apr 26, 2011 18:46:54 GMT -5
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Post by happyskunk on Apr 27, 2011 0:07:17 GMT -5
Your welcome Holly, Here is another chart with San Martin in it. This time non-cumulative GDD (base of 10C). I wish they had a weather station in the Sacred Valley of Peru, Cusco is as close as I can get. It will be interesting how this year compares to last year. So far we have had another unusually cool and wet spring here in Lewiston. I heard that one farmer had to hire a scuba diver to go mud diving in order to attach chains to some equipment and pull it out of the mud. I am lucky I guess to have no mud problems myself, my soil dries out so quickly I have been watering this week to make sure my seeds germinate. It is amazing the differences in growing conditions just a mile away.
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Post by 12540dumont on Apr 27, 2011 12:19:31 GMT -5
Happy Skunk, We had 4 inches of rain, followed by an inch of snow. I thought it was going to be a new season called mud. Happily spring is here and the tomatoes are in the ground. I planted corn on Monday, and peppers yesterday. I was just trying to figure out what day to start the heirloom bean trial...
I need a new calculator tab for my computer!
Texas Gourdseed 120 days (2820 GDD) 1500 GDD planting to silk Trinity 68 days (1598 GDD) 1083 GDD planting to silk Santa Domingo Posole 100 days (2350 GDD) 1200 GDD planting to silk Augusta 79 days (1856 GDD) 1248 GDD planting to silk
Floriani goes in the field trial 100 days (2350 GDD) 1200 GDD planting to silk
Is it safe to plant Floriani on May 20th? I'm trying to keep the silking dates 5-7 days apart (125-175 GDD) between silks. Of course we all know, we can only guess. Weather or not. Holly
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