Good questions, but not easy to answer. Different areas of the contry require a different approach to get maximum results. Generally, the more materials you can mix in a load the larger the area you can cover. This varies from machine to machine and pump type to pump type. You can pump a heavier slurry with a machine that uses a positive displacement pump such as the Bowie gear pump or Finns progressive cavity pump,(PC pumps adds mega $$$ to cost of machine). Most Finns and a lot of Bowie machines use centrifical pumps. You can mix a heavier slurry with a mechanical agitated machine than you can with a jet agitated one. Mulch rates needed also determine the amount of seed, fert, and other materials you need to add to your hydroseeder. A good starting point for your mulch rate would be to try for around 1500lbs of mulch per acre. One 50lb bale will cover 1452 sqft at the 1500lb per acre rate. Northern folks might use a little less mulch and Southern folks a little more, but 1500lbs per acre sort of puts you in the middle ground for a starting point.
I use 200lbs in my 600gal capacity machine. Because of the mulch and other material I add, I can only get 500gal of water in the machine. This means I am mixing about 40lbs of mulch per 100 gal of water. The machine will handle a thicker slurry but I have less problems with these ratios so I stick to them. You can apply any mulch rate with any type of machine, it depends on your application technique. I can mix 50lb of mulch in 1000 gals of water and still apply a 3000lb per acre rate, might be a little muddy when I get done and is certainly more time consuming, but the point is dont get hung up on the mixing capacity of the machine as much as the efficiency and cost effectivness.
200lbs is 4 bales of mulch, 4 x 1452 = 5808 sqft total coverage area at the 1500lb per acre rate. At this rate it would take about 7 1/2 loads to do an acre. Figure the correct amount of fertilizer, seed and lime to do that acre and divide that by 7.5 and thats how much you should add to your tankloads.
You can visit the mulch manufacturers websites and find dealers close to you. Lesco and Ewing Irrigation are a couple of distributors with a lot of stores nationwide. You can also find suppliers by simply asking whoever you purchase a machine from. More info can be found at http://www.hydroseeding.org/
. You will also find a very active forum, (well its a little slow now because of the time of year), there that is dedicated to hydroseeding.
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