# Hay curing. Confirmed suspicions?



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

It appears (for a few days anyway) Wisconson is basking in reasonably good haying weather. 
In Southern WI the forecast id for 14 & 15 hours of sunshine, and 0.21" to 0.26" of pan evaporation and the northern part of the state has roghly 0.30" of pan evaporation.

In the Central_San Joaquin Valley they are also forecast to have 15 hours of sunshine BUT 0.40" to 0.45" of pan evaporation.

Of interest to me- For about two weeks there has been 12 & 14 hours of sunshine but just over 0.41" pan evaporation.

Near Madison WI folks need to use every trick to cure hay. 
In the SJV they can put up great Looking Hay with just a little effort.

My HERE is some where between the two locations.

The lesson is: the universal truths of hay curing are truly universal, but the local methodology to accommodate this truth will vary considerably.


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## Vol (Jul 5, 2009)

Everything is relative!


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## rank (Apr 15, 2009)

OK Hay Wilson....what the heck is pan evap anyway and how do you measure it and what do you do with it when you have it?


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

Pan Evaporation is a tool. Much as relative humidity is a management tool. 
The Weather folks have a large fairly shallow pan partially filled with water. They measure the decrease in daily depth in inches or in metric. 
In your corner of the world you will have more precipitation than evaporation. 
In this corner of the world we have roughly 36" of annual precipitation and 72" of annual evaporation.

If you irrigate the evaporation transpiration moisture will usually be (roughly) 66% of the Pan evaporation.

For the hay grower, the scientist have come up with the amount of total pan evaporation required to cure hay down to baling moisture. This total value is based on the yield and the percentage of the ground that is covered by the down hay. From what little I have looked in the more northern states in the humid east will have roughly 0.25" of daily pan evaporation. In the arid southwest states there is closer to 0.50" of daily pan evaporation.

According to information from Wisconsin a ton of hay with a full 100% of the ground covered with down hay will cure faster than hay in a 3 ft wide windrow in the hot arid climate of the Southwest. That is not to say the hay growers are stupid not to lay their hay out in a wide swath, because the same data tells us they really do not NEED the wide swath to cure hay. This gives the irrigated arid west both an economic and quality edge over the growers in the humid eastern states. 
Race Horse Hay from the west sells in Kentucky and Florida. Granted hay buying race horse people have numerous non feed quality buying criteria.


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## rank (Apr 15, 2009)

3rd paragraph confused me a bit. What are they saying is the pan evap req'd to cure hay?

Seems to me a very tough thing to quantify. In addition to the variables you mentioned (i.e. yield and ground coverage) there is type of hay, degree of conditioning, presence of ground moisture, and maturity of hay are three that come to mind. Seems to me that these three variables will greatly alter the pan evap required to cure hay?


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## rjmoses (Apr 4, 2010)

hay wilson in TX said:


> According to information from Wisconsin a ton of hay with a full 100% of the ground covered with down hay will cure faster than hay in a 3 ft wide windrow in the hot arid climate of the Southwest. That is not to say the hay growers are stupid not to lay their hay out in a wide swath, because the same data tells us they really do not NEED the wide swath to cure hay. This gives the irrigated arid west both an economic and quality edge over the growers in the humid eastern states.


From a marketing perspective, I would think that a wide swath would have more sunbleaching and, therefore, look less appealing to those who buy by color. I would think a narrow swatch would protect more of the hay from the sun.

If I could afford the extra day to dry, I would put mine in a narrow swath to keep the color.

Ralph


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## mlappin (Jun 25, 2009)

rjmoses said:


> From a marketing perspective, I would think that a wide swath would have more sunbleaching and, therefore, look less appealing to those who buy by color. I would think a narrow swatch would protect more of the hay from the sun.
> 
> If I could afford the extra day to dry, I would put mine in a narrow swath to keep the color.
> 
> Ralph


I've thought the same about tedding. With the weather conditions for the most part this year, tedding is a must.


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## saltwater (Mar 26, 2010)

In West Texas I put mine in a fairly tight windrow with a discbine. I do not rake except my turnrows that have been run over. I can cut on Tues. and Wed. and bale Thurs. and Fri. with moisture of 12 to 18%. If the humidity gets High Enough at Night, if not it is too dry to bale and I would lose leaves. This usually happens at least once a year. I very seldom get to bale in the daylight. Our normal rainfall is supposed to be 16 to 18 and we may actually get it this year. My first year we got 4 inches. This is with alfalfa by the way I have baled some grass at night that was cut that day.


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## scrapiron (Mar 10, 2010)

I now understand pan evaporation I think. The univ of Fl gives us the "Evapotranspiration" for our area every hour, how is this compared to or different from pan evaporation?? Can we use it the same way?

scrapiron


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

Here is a copy and paste from a free forecast. Pan evaporation is included.

Lowest Relative Humidity 63 59 48 
Hours of Sunshine 0 2 11 
Solar Radiation(Watt-hr/SQ M) 2157 2969 6528 
Pan Evaporation(inches) .24 .28 .33 
Drying Potential HIGH HIGH VERY-HIGH

I would not characterize the next three days as even fair drying days, but that may be just me. 
The forecast is for Saturday, Sunday, Monday. If I was ready to cut hay I would not until Monday with it's 0.33" of pan evaporation, and as important 11 hours of sunshine. But that just may be me and my messy management style. 
You can find this forecast at AWIS.com : Consulting, Data & Forecasts for Ag, Energy, Retail and Industry. In the upper right corner is a box for your zip code. Put the ZIP code you are interested in.

There are ways to get more site specific forecast, but that usually cost some money. Besides this works well enough.

Something Dan Undersander points out is a narrow windrow can require multiple days of additional curing time.

To answer your question, evaporation transpiration is roughly two thirds of pan evaporation. Fallow land will loose maybe half of the moisture that gets into the ground to evaporation.

Saltwater has a good example of not needing the drying potential of direct sunshine. If today was 1970 and hay was cut with a 9 ft mower conditioner, and baled with a small square baler, he could start mowing at 8 am and start baling that night around midnight. With the wider headers of today's mower conditioning systems, and larger heavier bales, and little or no chance of rain, he can just about do as he pleases. Believe it or not, West Texas is relatively humid. Relative to Nevada, Idaho, and Arizona. There are hay growers who MUST have the pivots running on four sides of their field to have enough moisture to hold their leaves baling at 3 AM! At the same time there will be hay growers who may go a week with the humidity never going below 80% in the hills of Appalachia.

Florida selling in Florida has several advantages. You can know personally your ultimate customer. The livestock animal. If you can ever get your colored hay in the hay rack and the prefer your hay's taste, smell, and feel better than something off a long haul truck, you will be in business. Problem is getting past the man with the check book and getting to your ultimate customer. 
It is amazing that livestock owners know so little about forages.


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

mlappin
I have a bone to pick with the fine state of Indiana. 
They are hosting the 2011 AFGC annual conference and haveing it in June. The most worst time to have a hay grower even consider attending.


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