English
Rule of thumb: Don't cultivate any deeper than necessary
Ensuring that cultivation costs are kept to a minimum it is imperative that only just as much work is carried out as necessary. Working too deep will only waste diesel and too shallow will mean poor straw rotting.
By following the five basic rules of thumb for straw incorporation then optimum working quality should be ensured:
Rule 1: As deep as necessary
The preservation of the soil structure is an important target in soil tillage. On the other hand, the greater or lesser amount of crop residues that remain from the previous crop have to be incorporated into the soil prior to the new sowing operation.
That means: The better the straw distribution provided by the combine harvester and the shorter the chop length then the less the intensity of the straw incorporation can be. At the same time the working depth/intensity after leaf crops, such as beet, potatoes or rape can be lower than after crops with large amounts of straw (maize, cereals). After leaf crops often just one relatively shallow operational pass is necessary.
When the pre-condition of good straw and chaff distribution quality is fulfilled, and in addition the subsoil is well structured and sufficiently provided with oxygen the general rule applies: 1 t straw/ha requires a minimum of 1 cm working depth for incorporation. On soils with a weaker structure, however, for example, on sandy soils which tend to compact, or in areas with temporary stagnant water the soil requires the top soil loosening down to 20 to 30 cm. Only in this way can sufficient oxygen supply down to the roots be ensured.
Rule 2: As flexible as possible
Theory requires: shallow stubble working (primary pass, e. g. using the Catros) followed by a deeper operation (secondary pass, e. g. using the Centaur). For different reasons (crop rotation, soil type and weather), however, this procedure can not always be implemented completely or in this sequence.
In fact the following rules apply (see Table. 4):
• When the first operational pass was shallow, the second operational pass is deeper to incorporate volunteer grain.
• When the first pass was deep, the second pass has to be shallow (not a cultivator) in order not to lift the straw again, possibly it can be left out completely.
• Sometimes both passes are reduced to just one pass which then normally takes place immediately before sowing the following crop. In some cases if the previous crop was rape it can even remain unworked until the actual sowing operation.
| Technique | Primary pass | Secondary pass | Notes |
| Alternative 1 | Shallow | Deep | Incorporation of volunteer grain & weed seeds |
| Alternative 2 | Deep | Left out or very shallow | Do not lift the straw again in the second pass |
| Alternative 3 | Combined into one pass immediately before sowing | ||
| Alternative 4 | Both passes are left out | e.g after rape | |
Rule 3: Soil moisture preservation
Above all, in areas where the soil moisture content acts as the limiting factor, evaporation should be prevented as far as possible. Therefore stubble breaking should immediately follow the combine harvester and so the output capacities of the compact disc harrow and combine harvester must be nearly the same. Working widths and operational times of these machines should be accurately matched.
The same applies to the operation of cultivator and seed drill, because any second pass and sowing operation also should take place within a few hours, the best being that both systems operate simultaneously in the same field. Thus the required acreage output of the cultivator depends on the acreage output of the sowing technique used. The target is also here to preserve the remaining soil moisture allowing the freshly sown grain to germinate. In cases of insufficient capacity of the cultivator this can be increased either via larger working widths following bigger tractors or by prolonged operational times or shift work within the time available for working in the field.
However, one has to bear in mind that shift work in regions near built-up areas may cause problems in case the residents are bothered by night-time machine noise. On top of this it is getting more and more difficult to find qualified people who are prepared to work also at night and employing less qualified people may result, not only in damage to the machine, but also in a reduced operational quality, for example by sowing errors. Everywhere, where such problems exist, the working capacity can only be increased by larger working widths.
Rule 4: Optimised straw incorporation
This rule is also valid in adverse conditions. Therefore, the Catros compact disc harrow is the preferred machine for stubble breakage. It is easily pulled and provides high area efficiency simultaneously with a low specific fuel consumption.
In case of problems, such as, for example, insufficient straw distribution by the combine harvester or long/lying chaff after lodged grain, the first pass is carried out with a heavy disc harrow or a straw harrow, if available on the farm. In this case, however, one can also – equipped with the appropriate shares – utilise a cultivator such as the Centaur to mix the straw into the soil.
Where dry conditions prevail and there are signs that straw rotting after the first pass is less than expected the rule then is: The less rot, the deeper the crop residues should be incorporated with the second pass.
In this situation some farms use the plough in order to loosen and mix the soil as deeply as possible. One preferably ploughs between maize and wheat and also following wheat or maize where the rotation is a following spring sowing (beet, potatoes, malting barley, peas, etc.).
These cultivation effects, however, can be achieved more effectively by using the Centaur. It also loosens the soil down to the desired depth and mixes in the straw without, however, simultaneously inverting the soil.
Rule 5: Quick and early preparation
In order to maintain time schedules, especially in bad weather conditions, farms have to have available, machinery capable of high work rates . This not only applies just to stubble working, but also above all however, to the sowing operation.
Sowing combinations with actively PTO driven cultivators are used in preference on small to medium size farms. Combinations of rotary cultivator/harrow and seed drill: Depending on working width (3 to 6 m) combinations with rotary cultivator/harrow and seed drill provide a daily output of 15 to 50 hectares where the advantage of the active combinations is an optimum combination of soil tillage and sowing operation.
If the total field area cannot be cultivated with an active combination at the optimum time, the AMAZONE programme includes the Cirrus sowing combination. These combination machines, equipped with pre-cultivation disc elements, manage daily outputs of 25 to 60 hectares (in working widths of 3, 4 or 6 m).
For even higher acreage outputs AMAZONE recommends the Citan solo large area seed drills in working widths of 8, 9 and 12 m providing daily outputs of 75 to 120 ha. However, they are not equipped with any method of pre-cultivation. So, the bigger the necessary acreage output of the seed drill is, the more this is at the expense of the intensity in the seedbed preparation, so much so, that in the end, a separate pass is necessary prior to sowing.