Shallow stubble cultivation
"Weed control in organic farming takes place between harvesting and sowing" - this quotation from Günter Kahnt, a former professor of crop production in Hohenheim, caused numerous students to sit up and take note. He was placing the importance of tillage before that of hoeing and harrowing in terms of its effectiveness. In addition to suitable crop rotation and the cultivation of clover grass on organic farms, tillage is still one of the most crucial factors in weed management today.
Besides plough furrows, shallow tillage is a particularly crucial aspect. Firstly, in order to regulate rhizomatous weeds superficially at a defined depth, but secondly, to also ensure that no weed seeds are directly worked in too deeply. The greatest success is achieved with a shallow first cut and subsequent tillage, particularly when dealing with dock, but also when ploughing lucerne. The 'head' therefore has to be separated first from the root, which is filled with reserve substances. However, 100-percent cutting through is necessary for that to succeed. 8 cm overcutting with a cultivator or even a rotary tiller should be carried out in this case; if necessary, passing over twice with an offset working direction is appropriate.
As in the case of volunteer rape, it is vitally important not to bury the seeds of weeds such as foxtail deeply immediately after harvesting, because they then have a tendency to enter into secondary dormancy and subsequently come awake again at the most untimely of moments.
The following also applies to conserving soil moisture after harvesting: the shallower the better the likelihood of guaranteeing the necessary germination moisture for intercrops, clover grass, rapeseed and the like.
The basic prerequisites for the shallowest possible cultivation are firstly, a field that is as level as possible without deep ruts and secondly, suitable technology. Unfortunately, the latter has proved rare in the past. Tillage implements that can operate at shallow levels over the entire surface (at least 8 cm overcut) without blocking but which remain 'in the soil' at the same time and do not merely scratch the surface or have to penetrate too deeply to remain 'in'; for a long while, packing all of this into one implement was only needed in organic farming. Not for no reason have such implements more often than not been developed by organic farmers themselves or by small, 'ecologically-sound' technology manufacturers to date. Until recently, the Treffler cultivator, the Vibrocat from EuM and, by no means least, the HEKO ring cutter were only familiar within the eco scene.
Fortunately, the general shift towards increased organic farming or intermediate forms such as 'hybrid farming' and 'fusion farming', which is also due in part to the looming ban on glyphosate, is causing an ever increasing amount of innovative technology focussing on shallow and ultra-shallow tillage to be launched onto the market, and even the long-maligned rotary tiller is currently undergoing a renaissance.
This year, therefore, stubble should once again be dealt with quickly after harvesting, but perhaps slightly shallower. That not only saves fuel but also conserves soil moisture.