Key Steps to Wide Swath Success

 Tom Kilcer, Cornell Cooperative Extension, Rensselaer County, NY

            A number of farms are planning on taking advantage of wide swathing their haylage in order to: 1, chop proper moisture haylage the same day they mowed it (beating the rainstorms); 2, increase the energy and reduce the protein solubility in order to get more protein from their forages (save on soy purchases); 3, get 300 lbs more milk out of every ton of forage.  The hardest part of switching will be the mental adjustment from how you formerly made haylage.  Wide swath is not a fool proof system, mistakes can be made! There are two key steps you need to take to be successful with this system change, when you start, and how you do it.

 First, you can’t make a silk purse out of a sow’s ear.  If you want high forage quality (to support a profitable high forage/low cost dairy diet) you have to start when it is high quality.  Actually you need to start a little before and finish a little after so the average forage is high quality.  Some farms use a date as the starting time.  Unfortunately, in the past 10 years, the optimum starting time has varied by 15 days.  This is a huge change that means the majority of the time you have missed your target.  Fortunately, combining the work by Ohio State University , and Dr. Cherney at Cornell University , we now have a predictor of when to harvest based on YOUR crop on YOUR fields.

As alfalfa gets taller in the spring, the forage quality decreases.  By measuring the height of the alfalfa, you can predict what the NDF (neutral detergent fiber – a predictor of forage milk producing ability) of the forage will be at harvest.  Grasses mature much earlier than alfalfa.  That is why we cut intensively managed grasses first, and alfalfa after.  Research by Dr. Cherney at Cornell has given us a preliminary calculation how far ahead the grasses are mature.   They mature at a similar rate as alfalfa but just start earlier.  Knowing this, and calculating the difference, allows us to use alfalfa as a predictor of when to start harvesting all your cool season forages in the spring. 

The system is basically called a phenological predictor.  That is a fancy term to describe the use of a plant’s growth stages in order to predict when to harvest.  We have done that for years with milk lines on corn.  Farmers who have used this system have found they were able to consistently nail high quality forage harvest dates.  They also found to their surprise that fields didn’t mature in the order they expected.  There was major differences between south facing and north facing fields.

The data in Table #1 gives the major indicators.  When ALFALFA measures 15 inches tall,  you should HARVEST your ALL GRASS FIELDS.  They are at peak yield of quality forage.  The grasses will run about 52 NDF which is equal or better than cream-puff 40 NDF alfalfa in milk producing ability. I know, there is no alfalfa in an all grass stand – chose an alfalfa field nearby!  When ALFALFA in your ALFALFA-GRASS MIXES measures 24 inches tall, that is when you harvest your ALFALFA-GRASS MIXES.  Finally, for those who can grow CLEAR ALFALFA, harvest them when the ALFALFA measures 30 – 32 inches tall.  Basically you start with you all grass stands, and gradually work up through the stands with a greater percentage of legumes in them.  You would finish with your all legume stands.

This will give you forage of the same high milk producing ability.  If it takes you a week to harvest all your haylage, then you should start a little earlier for each measurement.  What some farms are doing is harvesting their south facing grass fields first, and finish with their north facing alfalfa fields.

 The second major key in successful use of wide swath forage harvesting system is a six inch problem – between your ears!  You have to mentally and operationally change how you approach this system.  Mowing all day with the swathers open, laying the forage into a wide swath will simply give you haylage that is to dry to properly ferment.  Mowing late in the day and leaving it over night will ELIMINATE much if not all of the higher energy, lower protein solubility, and 300 lbs of potential milk gain /ton of forage dry matter.   This is where you need an attitude adjustment.  What you mow today must be in the silo today!  Only mow what you can merge (or rake) and chop in one day.    It takes as long to merge or rake as it does to mow.   Thus you figure for each hour of mowing it takes 1.5 hours of merging and chopping (single windrows) to get the crop off.  If you have one of the doublewide windrowers it takes only ½ as long.  If you double windrow it takes half as long to chop. Of course this assumes only one operator and tractor.  Multiple operators and tractors dramatically reduces the time to merge and chop, but you get the point.  You have to figure out for YOUR FARM, with YOUR EQUIPMENT AND LABOR, how long it will take to harvest.  Then only mow what you can get in the silo TODAY!

What we don’t have a clear handle on is the drying time between mowing and chopping.  Weather conditions will affect this. I can assure you, with wide swaths it is much shorter than you think!  In 2003’s study, we took a very heavy (46 inch tall material) first cut alfalfa under less than ideal drying conditions and dropped it to 65% moisture in a little over 7 hours.  This was without touching the swath!   Ken Herrington of Herrington Farm’s in Brunswick ’s experience was that if you move (rake or merge) at 75% moisture it quickly dries to haylage making moisture levels.  For our study we were below that 75% moisture level 4.75 hours after mowing!  Raking or merging then would have allowed harvest much sooner.  If our field was harvested when it was supposed to (at 32 inches not 46 inch), we probably would have cut the above drying times in half.   We hope to have the resources to repeat this study again this year and further quantify the steps necessary to make this system work.

A final note: it appears that the feed quality and fermentation benefits are bigger the higher the quality of the crop.  Most of our study was harvested to late for optimum quality.  With grain prices as high as they are now, and milk prices heading higher, this appears the year for maximizing forage quality.  With high forage quality you can go to a high forage diet and use the profits to fill in the monetary holes from the past bad years.  Wide swathing just might be the ticket to help you do that.    

Wide swath haylage dries three times faster than narrow swaths.  You need to be ready to chop much sooner if you are to avoid having haylage to dry for fermentation.  What you mow today must be in the silo today if you want the forage quality improvements.

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last updated 5/13/04