In the first part, we looked into the effects of climate change on tillage in agriculture. We analysed the advantages and disadvantages of tillage. Despite high annual precipitation levels, the water supply for crops is not always guaranteed. Farmers must therefore carefully consider how they can reconcile the advantages of tillage, such as the mixing of nutrients and the breaking up of compaction layers, with the possible disadvantages, such as water loss and destruction of the soil structure. Is direct seeding the solution to tillage problems? The complications with consolidation in particular show that in some cases less tillage can be more. The point which you are at in the crop rotation plays a minor role. To better compensate changing environmental conditions, direct seeding is becoming increasingly justified as part of our cultivation system. However, direct seeding never is an acute problem solver. On the contrary: it requires good arable conditions and, as described above, is more restricted by higher requirements of the site than other tillage systems. But why draw a strict line between tillage and direct seeding when hybrid approaches, such as StripTill, rotative direct seeding and the offset method, are alternatives and combine the advantages of both systems?Comparison of hybrid approaches The term "rotative direct seeding" describes the alternating cultivation within the rotation. Cereals can usually be established after taproot crops such as rapeseed or soya without deep tillage. Additional interventions tend to rather destroy the natural soil structure and unnecessarily consume energy and time. In Central European conditions, for example, the diesel consumption of direct seeding is only just under 1/3 of the consumption of inversion tillage per hectare and year. StripTill as a combined method provides a solution for narrow time windows and is usually used when the crops can benefit from an additional deep loosening also from an economic point of view or can utilise the faster warming due to the loosening in an extended vegetation period. In this respect, rapeseed and maize are the typical crops. While StripTill for maize does not always produce higher yields, with rapeseed it offers the possibility of luring the taproot downwards with concentrated fertiliser depots.Offset methods are ideal if variability is required. Primary soil cultivation and the creation of fertiliser depots are separated from seeding in terms of time. Traditional seed drills with only minimal soil intervention are often used for seeding. On problematic sites with black grass, pressure can be reduced with additional shallow cultivation passes. Moreover, the advantage of this separation is that the soil can become denser resp. consolidate naturally over the longer period between tillage and seeding and that capillarity is also established even in late, dry seeding conditions. However, if the seed drill is equipped with front tools, they should maximally be set to the seed depth level. Coulter technology for the respective seeding method But which is the optimum tool for the different conditions and circumstances?In general, a compact, consolidated soil has higher requirements on the seeding technology. Light coulter designs work wonderfully behind power harrows, but do not achieve the coulter pressure required for direct seeding. Heavy seeding units, usually with a wider row spacing and the possibility to apply a lot of coulter pressure section by section, place the seed at the same seed depth even in changing conditions. Tine coulters work best with short-cut organic material. Stones are moved aside, and the capillary action is achieved even in heavy soils. Disc coulters adapt better to uneven ground and move less soil, but have disadvantages with stones and in unfavourable conditions and without front trash wheels they sometimes struggle with hairpinning – the seed in straw residue.As in extremely dry conditions on heavy soils and deep seed placement, because of a lack of fine soil disc coulters only close the seed furrow if the machine setting is perfect, a preceding, ultra-shallow cultivation pass has become increasingly popular in traditional direct seeding areas. A quick pass with a knife roller or a very shallowly set disc harrow often is sufficient to avoid the drying chimney effect of intact stubble, to level slightly and finally to leave enough fine soil to close the seed furrow.Summary With regard to climate changes, the traditional, tried and tested system of intensive tillage followed by seeding has to be questioned. However, the aspect of considering tillage more as a kind of tool, for example to incorporate organic material, mechanically control weeds or carry out soil repair measures, also confirm its right to exist. On the other hand, there still are the advantages of direct seeding and reduced tillage - especially with regard to saving water. In this case, it helps to stop thinking in black and white. Regarding the changing climatic conditions, for example rotative direct seeding, StripTill and the offset method can be considered as more flexible and adaptable alternatives. Their integration into our rotations is already in full swing in regions characterised by drought (Central Germany), weeds (Western Europe) or moisture (England). You can read about the relationship between soil cultivation and water and nutrient balance in Tillage - false nostalgia or necessity? (Part 1). The full article was published in advance exclusively in terraHORSCH issue 28-2024.
