Once the grinding of the rice stalk and its subsequent incorporation into the ground had been discarded, the next step was to choose the most suitable type of baling machine for the conditions found in Valencian ricefields. There are three groups of machine in the market capable of baling fodder based on the shape and size of the resulting bales: conventional balers of small prismatic bales, balers of large prismatic bales (“macrobalers”) and rotobalers.

The rotobalers were chosen, given that these machines make large-sized bales (300-400 kg in the case of the rice stalk), with half the weight of the macrobalers and with a size and robustness which makes them suitable for small plots with difficult access points like those in Valencian ricefields. From the range of rotobalers available, a final compression model was chosen as opposed to a continuos compression model, given that they are most suitable for the harvesting of material with a high moisture content. These machines are shorter with a stronger chassis meaning they can withstand heavier bales.

In the Biocompost project, three John Deere 578 rotobalers were acquired, two in the year 2002 and one in the year 2003.

Once the rotobaler had been selected, the first tests were carried out, both in plots with good ground conditions (dry and without furrows) and in plots with swampy and muddy ground. A series of conclusions were drawn from these tests which would later determine the modifications to be made to the machines to obtain prototypes ready for functioning.

1. The plots containing dry land with shallow furrows (4-6 cm deep) or none at all, as is the case in the majority of those located on high land, could be baled with the rotobaler without any modification.
2. If the land is hard but with deep furrows (10-12 cm) it would be advisable to substitute the original tyres of the rotobaler for ones with a wider diameter.
3. In the above two situations, it would not be necessary to use “special” tractors.
4. In the “Tancats” plots, which have very deep furrows (30-40 cm) and very soft soil, it would be necessary to use the prototype, i.e. with the adapted tractor-rotobaler assembly.
5. The adaptation of the rotobaler involves installing a telescopic axle in order to adapt to the different types of furrows and equipping the vehicle with higher wheels so that the harvester can work properly.
6. The modification of the tractor involves the adjustment of the width of the axle through the positioning of special adapters and the addition of special wheels for marshy land.
7. The adapted tractor-rotobaler assembly works well in the most unfavourable conditions and those characteristic of swampy deeply-furrowed land.
8. When working on land with deep furrows, it is best for the harvester to work without the auxiliary wheels and to operate in its highest position.