• The amount of maize by-products, namely straw, cobs or roots, ranges from several tonnes to as much as 30 t/ha, depending on a number of factors. The ratio of grain yield to harvest residues is assumed to range from 1:1,5 to 1:2.
  • It is a good idea to chop maize straw with a mulcher or a knife roller to make it harder for pests to overwinter and to facilitate the decomposition of organic matter.
  • Before ploughing, it is worth disking the stubble to mix the harvest residues into a deeper layer of soil rather than burying them at the bottom of the furrow, where decomposition will be hindered.

Maize is the second most popular crop in Polish fields, with a record area this season of 1,988 million ha. Of this, as much as 1,35 million ha is planted with maize for grain, meaning that the area is still larger than that occupied by rapeseed or triticale.

Large mass of crop residues

The mass of maize by-products, such as straw, cobs or roots, ranges from a dozen or so to as much as 30 t/ha, depending on a number of factors. The ratio of grain yield to crop residues is assumed to range from 1:1,5 to 1:2, depending on the variety, season, site, weather conditions, etc. This is a valuable supply of nutrients and organic matter, but it is also a place where pests overwinter and pathogenic fungi develop.

Unlike cereal crops, maize straw is generally not collected from the field. Why? First, it is thick and stiff, and second, it is almost always wet. It is sometimes collected, but this is very rare. One use is as fuel for heating the dryer in which the grain is dried. In this setup, dry cereal straw is burned first, and then wet maize straw is added; because of its moisture content, it must first dry out in the fire.

Shredding and mixing evenly with the soil

As noted above, a large amount of maize straw remains in the field after harvest, and the stalks are very long. In addition, pests readily overwinter inside them, which is why shredding is so important. This is done using a mulcher or a knife roller, which cuts the maize stalks into small pieces. Shredding also has the benefit of speeding up the decomposition of organic matter. This may also be a good time to apply fertilisers or other products that support straw decomposition.

The chopped post-harvest residues then need to be mixed into the soil, either shallowly or deeply, depending on the specific cultivation practices used on the farm. A disc harrow works well for this, preferably set to the greatest possible working depth. When there is such a large amount of post-harvest residue, it is important to mix it into as thick a layer of soil as possible to prevent a straw mat from forming, which would restrict water movement through the soil and the root development of the following crop, as well as promote undesirable anaerobic decomposition.

Winter ploughing after grain maize

If we decide to plough after harvesting grain maize, we should do so only after chopping the post-harvest residues and mixing them into the soil. One advantage of ploughing after maize harvest is its effectiveness in controlling fungal diseases and certain pests. One disadvantage, however, may be the accumulation and burial of post-harvest residues at great depth, which could increase the likelihood of undesirable anaerobic decomposition.

Where possible, ploughing should be completed before winter so that the soil does not dry out in spring. Winter ploughing is considered to be correctly timed when carried out after frosts have set in, which makes it easier for heavy machinery to access the field and for the furrows to be properly turned. There is no point in ploughing soil that is heavily waterlogged or even muddy, as its structure is severely damaged in these conditions, making it difficult to speak of any benefits from the operation.

It is extremely important to consciously select the working depth for the specific field, something that many farmers, unfortunately, still forget. On lighter soils, lower settings are generally used to avoid bringing up subsoil and drying the soil out excessively. Heavy soils, on the other hand, require a greater working depth, ideally varied from year to year, for tillage machinery to loosen them sufficiently and prevent the formation of a plough pan.