# Applying Pan Evaporation.....



## rank (Apr 15, 2009)

OK here we have a chance to test the pan evap.

Unfortunately I haven't found a source of pan evap data for my Canadian zip code of K0K 1P0, but if I use Rochester, NY which is approx 60 miles to the SW, they are forecast to have .26" of pan evap tomorrow.

-Mowed 2nd cut alfalfa yesterday (Sat) at ~17:00.
-Tedded this AM (Sun) at approx 10:00 while dew was still on.
-Checked moisture with a microwave today at 19:00. Moisture = 33%

_Q#1: What time tomorrow should I rake if I want to bale at 13% moisture?_
_Q#2: What time will the hay reach 13%?_


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## IAhaymakr (Jun 4, 2008)

I am going to assume for the sake of conversation that your climate is similar to mine in nwIA. I don't necessarily dispute the pan evap theory, but I generally like to follow the dewpoint to make decisions here. Unless your dewpoint is in the high 40's that hay of yours won't be 13% til wednesday, at best. As an example, I cut a 3rd crop of alfalfa last sunday, with super conditioner rolls, tedded monday, raked friday, tried to bale friday, tipped saturday, and finally round baled saturday night because it never got dry enough to big square bale. The humid air just won't dry hay. Our dewpoint was in the high sixties all week, probably pan evap was quite low. Good luck with your hay


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## rank (Apr 15, 2009)

Dew point was 60 - 68 today. Relative humidity actually got as low as 73% at one point this afternoon. Felt like we were in Arizona. High of 85 and humidity of 60% forcasted for tomorrow (Mon)............I'll believe that when I see it. Tuesday we get an inch of rain, so looks like it will be baled tomorrow.


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## IAhaymakr (Jun 4, 2008)

Are you going to put it up as baleage? I can't imagine it going good as dry hay with a dewpoint that high. I don't think I would even bother driving out to check it here. If that works I'll need to order a Macerator right away.


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## rank (Apr 15, 2009)

We pulled in there with the balers at ~3:30 pm this aft (Mon) and the Harvestec 464 in my baler said 11 - 14% in the windrow and 17 - 20 around the tree line. Humidity was 73% when I checked my little meter in the house today. Sun was shining and there was a slight breeze. High was supposed to be 85 today and it felt like it.

Now for the rest of the story. I tedded this AM at 07:30 with the dew still on. Went back at 11:00 and it was starting to get dry on top but you could see that underneath was going to be a problem so I tedded it again. If we had a good twin rotor rake this would have been the time to use it but I don't so I told the rake man to start raking with the vee rake at 1:30. We started to bale at 3:30.

You can have the best drying day in the history of hay making, but if the stems aren't cracked and the bottom of the swath doesn't get sun and air, it will still take forever to cure.

So to recap:

Saturday July 10:
Mowed 2nd cut alfalfa at ~17:00
Conditioned/tedded at ~ 17:30

Sunday July 11:
Tedded at approx 10:00 while dew was still on.
Checked moisture with a microwave at 19:00. Moisture = 33%

Monday July 12:
Tedded at ~ 07:30
Tedded at ~11:00
Baled at 3:30, moisture = 11% - 14%
Yield was ~1400 lbs/acre average


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## IAhaymakr (Jun 4, 2008)

I think I understand how you got that to work...lower yield than what I deal with. The hay I spoke of previously was right at two ton to the acre. Most of what we cut with the abundant moisture this year is at least 1.75 ton.


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## rank (Apr 15, 2009)

IAhaymakr said:


> I think I understand how you got that to work...lower yield than what I deal with. The hay I spoke of previously was right at two ton to the acre. Most of what we cut with the abundant moisture this year is at least 1.75 ton.


Yep....we cover alot of ground to get what we get. Doesn't look as bad in a wet year tho. 2 tons/acre....is that 2nd cut?


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## IAhaymakr (Jun 4, 2008)

Yes, that is 2nd cut at two ton. We started cutting 3rd sunday, and it will be nearly 2 ton again. Lots of rain and plenty of sun and heat. I haven't seen it grow this good for a few years. Usually cuts 2-4 will be 1.5 ton or so and 5th will be around a ton. It takes time and tedding to dry that much volume. This year it seems like it never really gets good and we end up round baling a lot of it.


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## rank (Apr 15, 2009)

IAhaymakr said:


> Yes, that is 2nd cut at two ton. We started cutting 3rd sunday, and it will be nearly 2 ton again. Lots of rain and plenty of sun and heat. I haven't seen it grow this good for a few years. Usually cuts 2-4 will be 1.5 ton or so and 5th will be around a ton. It takes time and tedding to dry that much volume. This year it seems like it never really gets good and we end up round baling a lot of it.


Yikes that's some serious yield. How much is getting cured into dry hay in your area? I never thought I'd be happy to have less yield and more ground to cover.

The wheat and straw must be good too?


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## IAhaymakr (Jun 4, 2008)

Wheat?? Not much here. This is corn country. Some big dairies around, most like to chop thier alfalfa to assure quality feed. Most of the dry hay is round baled, usually too quickly. I am the odd-ball doing dry hay in big squares. The dairies like western hay better, but high freight cost gives us an edge into local hay sales. It can cost 90$ to get hay from Idaho. I also grow grass alfalfa mix to sell into the horse, zoo, companion animal market. Some will get exported too. It finds its way into the south too, we don't have blister beetles here so the high end horse people like our hay down there. Why is your yield so low? Poor soil? I generally won't even harvest a crop that I think won't make a ton per acre.


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## rank (Apr 15, 2009)

IAhaymakr said:


> Some big dairies around...


Yes, that's our market too mostly



IAhaymakr said:


> ....most like to chop thier alfalfa to assure quality feed. The dairies like western hay better, but high freight cost gives us an edge into local hay sales.


Yeah but what do they fed their dry cows? Most of our customers are dairies that fed our hay to dry cows free choice. Cows like it because it's soft and palatable and the farmers like it because the cows don't refuse it and it's low potassium.



IAhaymakr said:


> It can cost 90$ to get hay from Idaho.


90? Is that just the trucking? My customers are paying $200 for 150 RFV from Id. Shipped in by rail or it would be alot more that $200. They're paying $235 for 180 RFV trucked in from KS



IAhaymakr said:


> Why is your yield so low? Poor soil?


That's part of it. We farm a shallow clay gravel here that would make a Hawkeye's skin crawl. Biggest part though is that it hasn't been seed, fertilized or sprayed in years and years. We do 1100 acres of certified organic and we've been yeilding ~1300 tons in a season the last few years.


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## hayray (Feb 23, 2009)

I am reading these humidity numbers and those seem real high, even for your climate so maybe I am thinking they are something else. Those are realiative humidity levels measured in ambient air or are those window humidity levels? Also, how do you find the pan evap. forecast for your area? What would your dewpoint levesl be forecasted on a typical day when the forecast is 85 F and the humidity are at those levels? Thanks for any further explanations.


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## rank (Apr 15, 2009)

hayray said:


> I am reading these humidity numbers and those seem real high, even for your climate so maybe I am thinking they are something else. Those are realiative humidity levels measured in ambient air or are those window humidity levels?


I dont know the difference Ray.

A government weather station 5 miles away on the shore of Lake Ontario is currently reporting 93% relative humidity. 
I am ~ 1 mile from Lake Ontario and the little meter on my fireplace mantel says 81% humidity.

Below is a copy and paste from Intellicast.com.

_8:00 AM on Friday 16 Jul 2010 (Local Time)
Rain Showers
Rain Showers
72°F
Feels Like
72° Station: CYTR
*Humidity: 78%*
Wind: 8mph
Dew Point: 64°
Visibility: 6mi[/QUOTE]
_
[/I]


hayray said:


> Also, how do you find the pan evap. forecast for your area?


I don't have a source for that. Closest I could find was Rochester, NY by using the link Haywilson provided.



hayray said:


> What would your dewpoint levesl be forecasted on a typical day when the forecast is 85 F and the humidity are at those levels?


See above cut and paste


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## hay wilson in TX (Jan 28, 2009)

To find a forecast pan evaporation for the folks in the states can go to:
AWIS.com : Consulting, Data & Forecasts for Ag, Energy, Retail and Industry
putting in your local ZIP Code will get this and more free weather forecasting.

Hours of Sunshine 14 12 12 
% of Possible Sunshine 99 88 89 
Solar Radiation(Watt-hr/SQ M) 7739 7098 7141 
*Pan Evaporation(inches) .41 .43 .44 *
Drying Potential EXTREME EXTREME EXTREME

This information will be for a rather large foot print, but it is useful. 
For our friends in Canada they probably can subscribe to the Agriculture Weather Information Service (AWIS). Possibly the Canadian Weather Service has some free weather information as does our NOAA / NWS.

All this STUFF are just a tool and not the complete answer to a maidens prayer. (Let alone a semi literate old hay farmer.)


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