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News and information from UC Cooperative Extension about alfalfa and forage production.
Tractor & Hay bales
by Bill Wilson
on August 23, 2013 at 3:54 PM
I agree whole heartedly with the idea that a wide swath will produce a higher yield as well as higher quality, for the Humid East.  
The idea is to cure the hay down dry enough to stop respiration by nightfall. Losses to respiration cannot visually be determined, only plot work will answer that.  
With a 2 ton cutting of alfalfa to cure down to 20% moisture requires an accumulated pan evaporation of 0.49" with a 100% width swath, but 1.91" of pan evaporation for a 2 ft wide (10% of the ground covered with hay) windrow.  
With a half inch/day pan evaporation the hay is ready to bale the first night while the windrow is ready to bale after 5 days. Figure 0.25" day one, 0.50" days two, three and four, the hay will be dry enough to bale sometime on day 6. Some time when there is enough humidity to bale the hay.  
Here Dan Undersander and I are in agreement.  
But WV's is telling us that we need 90% relative humidity, down next to the hay, to rake hay, if the 40% hay moisture is a good idea for raking hay.  
As I understand the problem, 70% humidity is not a sure thing for much of the Arid West. Not even down next to the swath or windrow. With a 70% RH the hay moisture can be in the 17% to 20% moisture range. Supposedly at 20% moisture for raking we can expect a 12% DM loss and a 20% leaf loss.  
The question is will there be a greater Dry Matter & Quality loss with more than one day of respiration or from leaf shatter from raking hay that is not tough enough to rake.  
Here in Central Texas I can expect the hay essentially dead by sunset if I finish mowing by our 3 PM. No overnight respiration!  
I can rake that hay at first light with a good dew with minimal leaf loss.  
Bale the third day as the humidity is going down to 70% humidity, at the windrow.  
I have always assumed that the Arid Western States did not NEED the wide windrow because the <20% RH and gentle 20 knot breeze made it unnecessary.  
Relative Humidity  
The devil is in the details and there are a number of details.
by Bill Wilson
on August 30, 2013 at 3:17 PM
Some links for you. Hope the links stay active.  
This one has a number of pictures and charts and is slower to down load.  
Interesting to me is the quality cost of the narrow windrow.  
This one is very simular to the one above, but has fewer pictures and downloads quickly. It was presentated at one of the outstanding December California Alfalfa Seminars. I heard this presentation. It required several readings and some careful study to appreciate the wisdom of this presentation.">  
Slightly dated but still valid information.  
Consider 2013 December conference at Reno.  
Look at the proceedings from 2012.  
Notice there are both the written presentation as well as a video & audio presentation on most topics.  
The nice thing about Reno is Southwest Airlines.
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