# Alfalfa Cutting and Drydown Questions



## Gearclash (Nov 25, 2010)

I've been thinking about the Universal Truths of drying and baling alfalfa, and have some questions regarding the first day of drydown.

What triggers the opening of the stomata first thing in the day? How does a cloudy day affect that? Or temperature?

What is the trade off of cutting as early in the day as possible (maximize open stomata time) versus having the plant covered in dew? HERE we can have dew that tends to persist until 10:30 in the morning or later.

How does cutting as early in the day as possible (maximize open stomata time) affect the RFV? This would be within the day cut. I realize there is an optimum plant maturity for RFV.


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## Bob M (Feb 11, 2012)

I have been pondering the same questions. Cornell University has done some research on making haylage in a day. In that sudy I think they mowed without crimping or conditioning the hay, which did not damage the stem and allowing the plant to continue to photosynithis (sp) after cutting. We believe that getting the quickest drop in moisture before the first night fall is important, not sure we are correct but that is our thinking. We usually start mowing by 8 A.M. and ted and or re-crimp fairly quickly. Some times on later and lighter cuttings and when ground is very dry and air is very dry we might not ted. Not sure there is an exact way but this works for us. Bob


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## brandenburgcattle42 (Sep 6, 2012)

Me personally am interested to see what you guys say about cutting early with a heavy dew versus waiting for it to dry off. Will an extra three maybe four hours of sunlight help the drydown even if it is loaded with dew?


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

The Book answer is you want to cut after the dew is off the plants, to prevent the spread of any diseases.

Back in the dark ages I started mowing at first light.

As I understand the stomata open when the plant is pulling moisture up from the ground, to provide a path for water vapor and oxygen to escape.

As far as I know the little holes in the leaves are open as long as there is sunshine and the crop is not having difficulty pulling up the moisture. 
Possibly if you dip the cut ends in wax to close the pipes the stomata will close, but until the plant dies unless it is put in the dark, The hay inside a windrow is in the dark, the stomata stay open will close.

Depending on the expert doing the analysis we need told to cure the hay down to 47% or 42% or 40% moisture to avoid respiration over night. 
Now the leaves can dry down fairly rapidly. Say IF the leaves dry to 35% moisture and your average moisture is 42% then the stems are at 49% Moisture. (WAG numbers) You can do your own postulations if you like.

A lot depends on your location, the strength of your sun, the humidity and wind speeds, for good pan evaporation.
Usually I rake the morning of the third day, and bale with the humidity on the fourth day.

June I may rake the morning after mowing and bale the third day, If the hay is stem snapping dry before dark, then I feel comfortable baling the next day.

I have baled hay the 14th day after cutting.
I have baled hay the day after cutting, also.

There is as much art as there is science to putting up hay.

Granted the science is there, we just can not measure it accurately enough.


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## Gearclash (Nov 25, 2010)

> The hay inside a windrow is in the dark, the stomata stay open


Thank you for your response, hay wilson. I am confused by the line above, wouldn't the stomata close in response to the darkness inside the windrow?

This leads me to my next question: when is a wide thin windrow thin enough? Obviously that will vary with tonnage. Is it worth teddering alfalfa to get back to the cutterbar width? We have been dropping a about a 7' swath behind a 14' cutterbar for many years now, so about a 50% coverage of width. On a self propelled mower it is difficult to lay a swath any wider than 7' or so.



> Usually I rake the morning of the third day, and bale with the humidity on the fourth day.


This sounds similar to our timeline. However we almost always rake the morning of the fourth day and bale that later afternoon or evening. Getting the stems snapping dry and then baling with humidity is a rare luxury here.


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

Thank you Gear Clash I corrected my post above to the stomata will close.

Dan Undersander gave a lecture with a chart demonstrating how a wide windrow will cure down faster than in a windrow.

I too his chart printed it on graph paper and extended some of the lines to build a chart figuring how much pan evaporation is needed fo dry from 80% moisture to 20% moisture.

My NH 411 as set up will cover 88% of the ground with cut hay. Then using my best estimate for yield and using the free pan evaporation from AWIS.com 's free zip code forecast I get three days forecast. If the chart indicated the hay will be dried some time the thrid day, I rake the third morning and bale the fourth day usuall startting about 11 am, Ususally the humidity will be 70% about 11 am HERE. Probably later There.

I try not to rake the morning of baling becouse that rolls some of that surface dew into the windrow and delays drying enough to bale. Except for the times I expect to have more hay on the ground than I can get done in 2 hours. Then I will rake a third of the field that morning, and bale that hay last. Usually when I do that the hay is getting too dry to bale, and then I find the today raked hay and the moisture goes back up close to 16% maybe even 18%.

E -mail me at [email protected] if interested & I will attempt to send you a copy of my home made chart.


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## aawhite (Jan 16, 2012)

Alfalfa takes up sugar/starch during the day, drops at night. So. in theory, late afternoon cutting has more digestible sugars. A lot of other factors come into play, so it may or may not be worth taking this into account.


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## endrow (Dec 15, 2011)

our climate is different here indeed I would always focus first on linking with the weather to bail the hay before it rains Cosmetics mean a lot on the way we sell cutting as early as possible in the day and getting the most drying in before the first night fall means a lot for cosmetics


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