Twenty years ago the concept of manipulating windrows after cutting was something to avoid.  Labor and machinery constraints simply dictated that such a practice added to the inefficiency of the process.  Times have changed and recent research from New York has indicated significant improvements in forage quality from hay cut and laid in a wide swath compared to the same hay cut and laid in a more traditional narrow swath.  The primary reason for the quality improvement was attributed to a faster dry down time and the resulting decreased amount of plant respiration (the breakdown of plant carbohydrates) between cutting and harvest.  It all made perfect sense.

         Many producers have since, to some degree, adopted this haymaking management system and there have been more research trials performed.  This period of experimentation has helped verify some things that we anticipated to be true, learn some things about the system that simply are not repeatable, and discover some current barriers to implementing the system. 

Dry Down Rate

        It seems intuitive that hay laid in a wide swath will dry faster than hay laid in a narrow swath and all of the wide swath research verifies this assumption.  A swath laid at 75 percent of cut width or more results in haylage-ready forage within six to nine hours (see Figure 1).  In other words, hay in a day if cut in the morning or hay in one and a half days if cut mid- to late-afternoon.  A wider swath results in more uniform drying.

Figure 1.  Dry down rate of hay cut in a wide and narrow swath at the Arlington Ag Research Farm (2005).

         One of the barriers to the system is that not many mower-conditioners on the market are designed to lay a swath that is 75 percent of cut width, especially if the cutter is over 12 feet.  Swath width is limited by the length of the conditioner rolls.  This is a situation that design engineers will eventually overcome.  It’s also important to remember that if the swath is to be merged before chopping, it must be done when forage moisture is still in the 68 to 70 percent range.  Letting the hay get too dry for merging and harvesting has been the biggest mistake made by those who have adopted the wide swath system. 

Forage Quality

        Finally there is the forage quality issue.  The New York wide swath research showed significant increases in digestible nutrients and reductions in soluble protein.  Subsequent studies in Wisconsin and elsewhere have not always been able to repeat those findings.  Likely, variable weather conditions during dry down play a role.

        Is this lack of repeatability a reason to abandon the wide swath concept?  I don’t think so.  When dry down time is reduced, the chance to make quality hay improves because the number of haymaking opportunities between rain events increases and the chance of getting cut hay rained-on decreases.

        I recently analyzed Fond du Lac weather data from May 20 to June 10 (prime first-cut haymaking time period) for the past ten years and looked at the number of times there were three, two, or one consecutive day(s) without rain (Table 1). 

Table 1.  Consecutive Rain Free Days from May 20 to June 10 in Fond du Lac, WI

        During the 22 day period, the average was 5.5 chances for making hay with three consecutive days without rain and 9.6 chances for two consecutive days without rain.  There was an average of 14.4 single no-rain days.  Hence, your chances to make hay at the right time nearly double if dry down time is reduced from three days to two days and nearly triple from three days to one day.  In 2001, decreasing dry down time from three to two days increased the haymaking opportunities by four fold.  Over the long haul, the wide swath system will enable you to harvest more high quality hay than would be possible otherwise. 

        In summary, the forage quality advantages of wide swath haymaking are all related to faster dry down time.  These include reduced plant respiration in the field, enabling more opportunities to make hay at optimum quality, and a reduced risk for hay to get rained on.