Model 720 Dew Simulator

No dew? No problem.

Waiting for natural dew to soften alfalfa before baling is a challenge for producers in arid areas. Many producers have tried to spray over the windrow to bring the moisture content up, only to find that just the top of the windrow becomes soft, but the leaves still shatter off most of the hay.  The Model 720 Dew Simulator from Harvest Tec has now made simulation of natural dew possible.

The newly redesigned Model 720 Dew Simulator allows for the precise addition of water to windrowed alfalfa. The windrow will be as soft as if it had just received the ideal amount of dew. By spraying into the windrow prior to baling, moisture is added to all of the plant material. The water softens the hay, giving the hay the appearance and test of hay made with natural dew.
Become more efficient with the Model 720 Dew Simulator by opening your baling window throughout early morning and later evenings when operating conditions become a challenge. Take more control and become more productive baling on your schedule
Rehydrate and soften windrows and increase bale weights with additional leaf retention. In addition to higher yields, operators treating hay with the Model 720 Dew Simulator can expect better looking bales with more consistent weights


How it works

The Model 720 Dew Simulator runs as a separate pass before baling, and the machine preheats water to 240°F, and applies the hot mist to the windrow via a reel with tines that enter into the windrow and spray from the bottom of the windrow up, the same way that natural dew occurs in windrowed alfalfa. The heated water has been shown to soften the plant’s material more effectively than cold water, allowing the crop to retain more leaves.

What it does

  • Water is pre-heated to a target temperature of 240°F
  • 65 tine (85 tine option) cam reel enters and exits the windrow vertically, with no crop disturbance
  • Valve actuated tine rows only apply high pressure spray when inside the windrow
  • Valve actuator adjustable for windrow height
  • Valve actuation can be turned off for windrows with bottom moisture
  • 250-500 psi spray delivers fine droplets between 20 and 40 microns
  • 1% of a specially formulated surfactant added at a cost of $2/ton (10 gal per 1000 gal water)


  • Reel wing lowers to the right of the main chassis
  • Water tank is operator supplied to be pulled directly behind (1000 gallons recommended and will treat 80 tons)
  • PTO driven pump runs on 1000 rpm to deliver 15 gpm@750 psi
  • 2 in-series diesel fuel water heaters deliver 750,000 BTU each for total of 1,500,000 to raise water temperature 180°F at 18 gpm
  • Water heaters use 5-11 gallons per hour of #2 diesel during operation
  • 70-100 HP tractor recommended

Operator Adjustments

  • Operation speeds between 2 and 10 mph to be matched to speed of baling
  • Water delivery of 10 to 18 gallons per ton depending on how dry the hay is
  • Treatment width is adjustable between 40 and 59 inches
  • Treatment height is adjustable between 8 and 20 inches
  • Tip selection is matched to treating/baling speed (10-60 tons per hour covered by 3 tip sets)

Re-hydrating windrows within seconds of baling in high evaporation conditions

Benefits of the Model 720 Dew Simulator

The Model 720 Dew Simulator is designed to re-hydrate dry alfalfa windrows from 6-10% moisture back up to 14-16% moisture in dry, arid climates that don’t see a lot of natural moisture and have to rely on the dew. By adding the moisture back into the windrow before baling, operators have the ability to open up their baling window, bale longer hours, and make better quality alfalfa bales.


Weight Gain from Reduced Leaf Loss

Total Tons Treated                                                                                       1000 tons

Reduced Leaf Shatter by Adding 4 Points of Moisture¹                       4%

Increase in Tonnage from Less Leaf Shatter                                          40 tons


Weight Gain from Additional 4 Points of Moisture Added

Total Tons Treated                                                                                      1000 tons

Weight of Additional Water per Ton (lbs/ton)                                      4%

Increase in Tonnage from Additional Water                                         40 tons


  Total Tons Added                                                                                       80

  Value per Ton                                                                                             $180

  Total Value Added                                                                                   $14,400

¹Based on laboratory study on alfalfa in a vibration chamber at different moistures conducted by the University of Manitoba in cooperation with Colorado State University.






Payback Calculator

The Model 720 is an investment to your operation that can increase efficiency and value to an operation. How about to your specific operation? Click on the Payback Calculator link below to see how the Model 720 Dew Simulator can bring value to your farm.

Model 720 Dew Simulator Payback Calculator


“With the dew simulator we can actually control exactly what we want as far as moisture leve in the bale. Typically we like to bale with the Dew Simulator and bale through an entire day. We don’t just shoot for a two hour target of time. We shoot for a target moisture and bale all day.”

Gale Carr, Fort Hancock, TX

Click Here to see the full testimonial!

“You can go from knocking leaf off like crazy to just incredible leaf retention, you're retaining all leaf. It's a definite improvement on our operation by far.”

Nick Lettunich, Fabens, TX

Click HERE to see the full testimonial!

“The dew simulator has brought the quality of the small square bales up tremendously. We can now put the dew moisture on ourselves and make a better product".

Fred McMinn, New Mexico

Click HERE to see the full testimonial!

We're seeing better yields, our tests are equal to hay put up with natural dew and in some cases even better depending on the field. Overall it has really changed the way we've run our production".

Kurt Bohrer, Wyoming

Click HERE to see the full testimonial!

“This process has allowed us to put up large quantities of supreme dairy quality hay; not only put it up, but put it up on our own schedule, without baling through the night. It is a lot less effort and we put up a lot more hay. We actually put up 360 acres in one day, using the Dew Simulator and running two balers.”

Rusty Lytle, South Dakota

Click HERE for an article featuring the Lytle's hay operation published in the Hay & Forage Grower magazine in January, 2019

"We start adding dew with the Dew Simulator and we can bring our moisture back up to 15-16% moisture, and our bales will weigh at least a hundred pounds more. The leaves are going into the bale and not only increasing weight, but the quality of the bale of alfalfa as well."

Jim and Doug Kizzire, Nebraska

"With the Dew Simulator you can get moisture in the bottom of the windrow, and you can soften the windrow and lot quicker. I try to bale really close behind the machine, and it's making really nice hay. It opens the window for baling. I baled hay at 8 o'clock in the evening the other night trying to see if I could make it work, and it made good hay."

Colin Bowler, Utah

Click HERE to see the full testimonial!














How does the 720 Dew Simulator Work?
Harvest Tec 720 Dew Simulator Animation
720 Dew Simulator Introductory Video 720 Dew Simulator Walk-Around
Dew Simulator Field Footage Small Square Bales and the 720 Dew Simulator
Dew Simulator Monitor and Setup Dew Simulator Winterization

Dew Simulator Valve Roller Rebuild Remove and Install Reel Hoses


Contact Harvest Tec directly for pricing and availability


Request More Information

Click on the links below for more information

Model 720 Dew Simulator Brochure - 2021

University of Utah study:
Comparison of Strategies to Remoisturize Alfalfa in the Windrow for Baling






Commonly asked questions about the 720 Dew Simulator

What size tractor is needed?

Size is not important, simply need 1000RPM PTO and preferably 10,000 lbs in weight. May need heavier tractor if baling in hills. Dew Sim + 1000 gal water tank will be about 15,000 lbs pushing tractor down a hill.

How long do you wait to bale? 

All dependent on evaporation conditions. Excessive heat (90 deg or more) or excessive wind (10mph or more) will usually lead to baling within seconds. If calm evening after sun goes down a grower would ideally wait 15 min allowing windrows to soften even more.

How many acres will 1000 gallons treat?

This is all dependent on amount of moisture in windrow.  1000 gallons typically treats 30 to 50 tons before needing to refill. Raising from 6% windrow requires more water than raising from 11% windrow.

Any special water requirements?

We want clean water to avoid plugging of filters/tips. 2 filters on unit. If really hard water we recommend an additive to keep minerals in suspension in water to pass thru tips. Surfactant is optional but can also improve dispersing of water droplet across plant material for better penetration and softening.

How do you know how much water to apply?

Guidelines are provided for setting pressure for flow rate but this is a minor learning curve. It is critical dew sim operator is speaking w baler operator throughout baling. The baler operator should be looking for baler pressures similar to ideal dew conditions.

Is it applying steam? 

No, we do not have a boiler but rather use water heaters. We are under pressure (400 to 1100 psi) so we are simply applying a “heated mist”.

How fast can you apply? 

Dew sim should always travel same speed as 1 big baler or twice the speed of 2 small square balers. If baling at 12mph the dew sim can treat at 12mph.

Can you bale all day with this unit? 

Quality is always jeopardized in the middle of the summer in the heat of the summer. The unit is meant to extend baling window a few hours before dew sets in and a few hours after dew burns off.   If the dew doesn't come in, just keep going.

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