The Straw – leave it on the fields or to granulate?

After summer field works, the straw may be left to naturally degrade and fertilize the soil. On the other hand, it may well continue its use in various ways: natural Biofuel, animal bedding and litter or even feedstock. Basic problem is the straw or hay degrades relatively fast, is not easy to handle and costly to travel for longer distances.

A solution to these problems is granulation. The straw or hay bales (rolls) are chopped into small pieces at first. Further in the line the pieces are pressed through a pellet matrix (die). Most common size, as opposed to popular wood pellets, is the 8mm diameter. Some other matrixes produce 10 or even 14mm diameter. While large pellets are no good fit for small animals, like chicken, the straw pellets can be later reprocessed using a pellet mill. Straw granulate can also be small to tiny fraction.

Granulated straw gains specific advantages versus straw bales or rolls. The product can be transported further, manipulated easier and more convenient to store.

Light weight materials can only be transported for limited distances because of fuel expense. Straw Bales, rolls, also sawdust in bulk is only possible to transfer for 30 to 50 km. Otherwise, cost of transport outweighs the cost of local material. This is subject to actual conditions in the market, but generally is a long-term rule. However, granulated production has this issue no longer. The density of straw pellets is 550-600 gr/l, making it even to any other product for delivery in full truckloads. This gives a possibility to deliver, in adequate transport costs, for distances up to few thousand kilometers, like any other product.

If for straw bales of roles manipulation one would need a tractor, a set of forks and certain load capacity, the pellets are by far easier to handle. The product can be transferred and stored as bulk, using conveyor belts, storage bunkers, automated spiral shaft etc. if used domestically, one only needs a shovel to remove pellets from big bags. If packed in small bags, it is even easier, as typically bags weight 15 – 20 kg. No scratching is needed before distributing in the animals fence either.

Pellets are packed in plastic bags. It’s protected from sunlight, moisture, rain, other physical damage or influence. Because of high temperatures (up to 95 °C) during granulation, all microbiological activity is gone, hence it’s safe to store for longer periods. However, it is still extremely important to ensure proper ventilation. Even minor excessive air moisture and ‘standing’ air can cause the mold and rot within relatively short time. Lastly, because of increased density, the space requirements are decreased. One big bag of straw pellets, which contain about 1 ton, takes only 30% space, if compared to Bales or rolls.

 

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