Mulching: Soil Cover for Profit

Laying ground cover offers numerous advantages, especially for specialised crops, and mulchers these days also lay plastic sheeting often combined with a transplanter and other machines so that more than one operation is effected in a single pass

Mulch and mulching have changed substantially in recent decades, and in substance too, for example, not only chopped bark, leaves whether shrivelled or green, hay and straw, but also PVC, polyethylene, cellulose, Mater-Bi, nylon, paper, gravel, lava fragments and cocoa rind and this list is by no means complete for all the substances now used by farmers to cover a piece of their land to keep the temperature higher during the winter and cooler and damper in summer. Mulching is also used to hinder the growth of weeds, protect the soil from erosion and avoid the formation of a surface crust. In any case, in professional vegetable and flower growing, the most common approach involves laying down a covering made of something with high elasticity and adaptability to the ground’s contours.

Mulchers are used to lay it. They work in open fields or in the closed spaces of greenhouses and crop tunnels. As machinery goes, they are rather simple, almost always working from a tractor’s rear three-point hitch. They lay one or more strips of the covering material which comes in varying widths. Special plough shares or disks cover the edges with earth to anchor the covering.

Plastic film rolls off a free-turning reel mounted on a strong support. The covered surface can be flat or shaped, graded convexly or like a flowerbed. As required, the film can be laid in a continuous strip to be punctured later when transplanting of the seedlings is carried out, or else the two operations can be carried out at the same time with appropriate combined machinery.

 

 

The basic elements

The metal frame is fitted for attachment to the tractor’s three-point hitch, with a strong, usually smooth and sometimes stainless steel roller to level and exert gentle compaction on the ground to be mulched. Just above, there is an axle holding the reel from which the plastic film unrolls. There is another small roller below as wide as the film to guide it onto the ground where two small pneumatic free-moving wheels press the edges into the soil. A pair of small shares or disks whose height and width can be calibrated come immediately after the wheels, moving a certain amount of soil to cover the edges and hold the film firmly in place and at the right crossways tension. Next down the line, you sometimes find two more wheels with the job of compacting the soil on the film’s edges, a useful option to stabilise the film, especially in windy areas.

 

 

Different combinations

Mulchers come alone or coupled with transplanters and other machines so that more than one operation is possible at each pass through a field. This is a valuable option that reduces working time and also soil compaction, an increasingly important parameter, especially for specialised crops.  The added operations can also include fertilising, some plant treatments and the installation of irrigation equipment.

 

Performance

Mulchers need no power from a PTO or hydraulic system, and need only limited power to be towed across a field. This means the tractor need be no more powerful than about 50 HP, although a model capable of laying two or three film strips simultaneously may need to be much heavier to ensure stability and hence would use a tractor packing power of up to 100 HP. When the film has already been perforated or is perforated when transplanting is effected, the machine is capable of 4-12,000 plants an hour in soil cubes already separated or to be separated.

Mulchers have also been produced for work between crop tunnels rather than on growing surfaces. In this case, one design lifts up earth in front of the machine, lays the cover and replaces the earth on top of it from the rear, holding down the cover to maintain humidity and discourage weeds in this key area.