NO-TILL/DIRECT DRILLING

One of the three main principles of CA is that no tillage is carried out. This means that the seed must be placed without prior preparation of the seedbed. As in full tillage systems, it is of course also important in CA that the seed is placed precisely and that it has direct contact with the soil.

This places special demands on the seed drills used in CA. There are generally two types of direct seed drills - tine drills and disc drills. With a tine drill, a seed tine is pulled through the soil and the seed is placed behind the tine. In a disc drill, a roller disk cuts a groove in the ground where the seed is laid and the groove is pressed in again. There are pros and cons to both types.

An advantage of the tine drill is that it works well to place seeds underneath surface crop residues. There is an increased likelihood that the seed will be placed in direct contact with the soil. Yet, with crop residues on the field, there is a risk of the plant material being dragged along with the drill.

Tine drills are less suitable for drilling in a large cover crop. Tine drills also disturb more soil than a disc drill, thus resulting in more weed seed germination.

In the disc system, a disc cuts through both crop residues and cover crops, but there is a risk that crop residues are pushed into the seed slot (hairpinning) and thus the seed does not come into direct contact with clean soil.

Both principles of direct drills are available in a multitude of different versions with and without fertilizer placement.

Example of a coulter seed drill (left) and a disc coulter seed drill (right) - Dale drill with seedhawk inserts and Weaving GD Drill.

Once the crop has been sown, the rest of the work in the growing season is comparable to what is known from traditional tillage systems. However, for the untrained eye, the direct drilled field might look much messier than traditional tillage fields.

It can be a mental challenge when one is used to the field looking proper, the soil being black and only interrupted by the emerging green rows of the new crop. In addition, it can be more difficult to assess whether the crop is developing satisfactorily and weed problems can also be more difficult to detect and assess.

Apart from this, normal management practice in terms of fertilisers and pesticide treatments against weeds, fungal and insect infestations applies. The harvest is also carried out as usual with the exception that the straw is often being cut and left in the field.

Even with a good distribution of the cut straw, it will often be necessary to distribute the straw further and this is best done with a straw harrow diagonally on the harvesting direction.

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