Makin' Hay

My friend Hay Wilson in Texas sent me this. It reminds me of my hay making days. It's pretty good.

"Ed I do not know if you can do anything with this.

Today was a big hay day here, and I got to considering how the Here - There differences are mentioned but not demonstrated.

So I used SW NM as one example and SW OH as the other example.

Southwest New Mexico Monday TuesdayAverage Value 05/24/10 05/25/10------------- -------- --------Lowest Relative Humidity % 7 8 Hours of Sunshine 14 13 Morning Wind Dir/Speed MPH W/13 E/09 Afternoon Wind Dir/Speed SW/12 SW/09 Pan Evaporation (Inches) 0.37 0.40 Drying Potential VERY HIGH VERY HIGH Solar Radiation (Watt-Hrs/SQ M) 8387 8389 Dew Intensity/Dryoff Time NO DEW NO DEW

Southwest Ohio Monday TuesdayAverage Value 05/24/10 05/25/10------------- -------- --------Lowest Relative Humidity % 38 40 Hours of Sunshine 12 12 Morning Wind Dir/Speed MPH SE/05 SE/06 Afternoon Wind Dir/Speed E/08 N/05 Pan Evaporation (Inches) 0.27 0.27 Drying Potential HIGH HIGH Solar Radiation (Watt-Hrs/SQ M) 6940 7534 Dew Intensity/Dryoff Time MODERATE/ 8AM LIGHT/ 7AM

There is a major difference in lowest RH for the days.

The pan evaporation may not look like much but those numbers are significant.

Hopefully a chart I use to estimate curing time nicely demonstrates the advantages of a wide swath in the Humid East but the hay dropped into a windrow by the swather works just fine in the Arid West. In fact, though the Arid west has sunshine in abundance they really do not need the drying assistance of the sunshine. Hopefully the pan evaporation chart will work. (I can't get it to copy out of the email so I will post it when and if we figure out how to share it with you. I get the concept but need to share it with you.)

This chart is telling us how much pan evaporation will be required to cure alfalfa to close to a baling moisture level.

Assuming a 2.5 T/A cutting. Figure a half day effect for the day the hay is cut.

In our humid east example 0.27" /day For 0.13" day one, plus 0.27" for each following day.
In our Arid West example 0.37" /day For 0.18" day one, plus 0.37" for each following day.

Day one at .13" + day two .27" = .40" + day three .27" = .67" + day four .27" = .94" + day five .27" = 1.21"

So in theory the hay will be ready to bale during day four the hay will be ready to bale using a full 100% (tedded) swath.

Hay dropped into a windrow will not be ready to bale until day six. Maybe
A 3 ton cutting will take even longer.

Day one at .18" + day two .37" = 55" + day three .37" = 92" + day four .37 = 1.29" so their hay can be baled the night of the fourth day. Even a 3 ton cutting will be ready to bale the night of the fifth day. Even if dropped in a windrow behind the swather.

I may have become a bit confused with the numbers!

Bill "

No, I think you are right on, Bill. I had this in ag engineering class over 40 years ago, kinda rusty but it looks right. Several have emailed whether to cut hay or not in case it doesn't dry enough by the next predicted rain on Friday. Your numbers show it is iffy!

Ed

PS, I liked this one on tedding:

A tedder is a good tool but is not magic.

There are a few rules we must work with to cure hay.First is 75% of hay curing is with sunshine on the hay. Yes hay will dry in the dark with a good breeze and almost no humidity.

Second the 25% of the remainder of the curing effect is from wind, low humidity, dry ground, and some other factors.

The first big moisture loss (30%) is the first day, with the moisture going out the openings in the leaf underside. This is true as long as the leaves are in sunlight. Put the leaves in the shade and the stomata (leaf openings) close. This is the reason we want to drop the hay in as wide a swath as possible. This is also why the ideal time to use the tedder is right after cutting.

Conditioning has little or no effect here. Where conditioning comes in is with the sunshine directly on the stems the moisture is warmed in the stems and this builds vapor pressure and forces the moisture out the nearest opening. This effect is seen not only on the first day but on following days.Another rule we need to work with is there is leaf shatter, total dry matter loss, & quality loss if raked or using a tedder when the hay's moisture is below 40%. We can assure we have this moisture in the few hours after mowing, or if the relative humidity is at or above 90% (at ground level!). (You gain by quickly getting the hay down to below 48% moisture because this is where the cells die and quit burning up energy. The hay will have more energy and as importantly be accepted better by the animals.)

The graph on page 9 http://utahhay.usu.edu/files/uploads/UHFS07%20pdfs%20for%20web/Undersander%20Swathing%20and%20Conditioning.pdf is very instructional. You will notice how much more pan evaporation is required for a narrow windrow than for a full width exposure. This graph is also a good tool to estimate how long it will take for the hay to cure. Allow me to say again this is all driven by the power of direct sunshine. It really applies to hay put up in our humid climate.

Our friends in the Arid West with their climate have different problems. There the hay will be too dry to rake within hours of mowing and the humidity will never be high enough to allow raking with minimal leaf shatter. Their almost zero humidity and almost sure good breeze means they do not NEED the direct sun shine to cure the hay. They probably have in excess of 0.50" of pan evaporation. That is a climate where rain evaporates before it can reach the ground! At least during the summer. All the above is what we must work with just to get hay dry enough, where we can safely bale, with out heating or molding.

There are no strict rules on using a tedder. I do not use the tedder when the yield is less than 2 Tons/A. When the yield is down close to a ton/A I will drop the hay in a wide windrow rather than a wide swath.