The process of soil mixing for nursery and green houses started with vary basic roots. Some people started with wheel barrows moving the soil back and forth with very back breaking results. Others layer the different ingredients such as pine bark,peat moss ,wood shavings , fertilizer etc on a level surface and simply use a hand tiller ,others upgrade to a tiller behind a 3 point hitch on a tractor. Others spread the different materials out on a mixing slab and take the front end loader and scoop up the materials into a pile and roll the ingredients until the are mixed. Many argue about the quality of the mixing especially when it comes to mixing in the fertilizer.
Of course some crops like woody ornamental s are not as sensitive and these types of mixing and seem to work for some growers. However crops like the greenhouse operations are more sensitive than these and other means of mixing are entertained.
Most growers will start out with a paddle or ribbon blender like the YJI Soil Mixer . Some project growth and will purchase a YJ2 Soil Mixer. Most of these styles mix no more than 10% sand. Both these mixers use a ribbon style on a horizontal shaft that move the materials in a figure eight and pulling the blended soil to a center discharge. Even if they grow into very large operations they will usually keep the mixers for propagation mixes . Flat and pot filling attachments can be added and its not uncommon for batch mixers of this type to be at a growing operation for 25-30 years or more. The next step towards more production is usually a 4 yard mixer. Some companies offer batch mixers that are paddle style. The ICM-4 yard incline mixer is truly a unique machine . The 4 yard incline mixer has a chain system inside that runs over 6 sprockets with horizontal paddles that move up a slope and rolls the media gently folding the product . This style like the others can mix a batch in 2-4 minutes . The ICM -4 yard mixer can totally discharge in 90 seconds. It can also be used as a feeder for a flat and pot filler and a simple bagging machine with a timer , soil chute and foot control. Many growers can easily mix over 100 yards a day with this machine. Again no more than 10% sand is recommended . People need to understand that these style mixers are not for top soil , if top soil is to be used it should be included in the sands 10% number. Most soil mixes run around 25 to 26 pounds per cubit foot and this is what most soil mixers are designed for.
When a 10 yard batch mixer is needed it would more than likely be a paddle design and the cost begins to escalate . When this is the case growers and commercial soil companies usually start looking at continuous soil mixing systems.
Continuous soil mixing systems have a series of material hoppers that discharge on to a moving conveyor belt. These materials layer on the belt and generally go through a mixing head or tumbler. For example it might have a 10 cubit yard bark hopper ,then a 10 cubit yard peat moss hopper , then maybe a 4 cubit yard pearlite hopper , and a 4 cubit yard sand hopper. Then a series of small fertilizer hoppers (STAINLESS STEEL) with a capacity of say 200 pounds or so. With all the ingredient hoppers layering the materials in the desired ratios then its ready to go through the mixing head. The mixing head is a series of blades or paddles that are placed at opposite angles and turn about 300-400 rpm in the same direction as the flow of material. After the material is mixed it usually is conveyed to soil bins, overhead conveyors,leading to automated potting and flat filling systems or trucks.
Some continuous mixing systems soil gates are manually set for percentage ratios and others are automated. The manual systems are alright when not many formulas are desired. When many formulas are desired a computer with the proper software is usually best. The software does not control the gate openings but rather controls when the belts come on . The timing of every hopper can result in a properly layered materials . With the proper software the customer is unlimited in the formulas that he can store in memory. The customer can run a 1 yard batch and even as high as 999 yard batch. With the computer ,unlike the manually controlled gates, when the batch is finished the belts are clean. This helps keep down corrosion making the machine operate with less maintenance.
If you would like more information or have any questions please contact
Sean Ellis or Mitchell Ellis
usa 252 649 6466