What is Planting Green?
Simply explained, it is direct sowing in green catch crops. And that actually says it all. The new main crop is sown in a green catch crop that is still in full growth. Unlike the strip-till method, there is no tillage whatsoever. The seed is merely slit.
The focus here is on sowing winter cereals in freezing cover crops. However, this technique can also be used for summer crops such as maize or soya beans. Here, the seeds are usually sown in green rye or winter turnips. When planting green in summer crops, however, herbicides are usually required to eliminate the catch crop. In the case of flowering crops, however, a roller crimper is often sufficient, making herbicides unnecessary. This type of cultivation is therefore also possible in organic farming.
What are the advantages and disadvantages?
After early-clearing crops, a fast-growing and biodiverse intercrop mixture is sown, which can develop very lushly. It covers the soil in hot weather, nourishes and protects soil life, promotes soil fertility, prevents erosion, encourages insects (many ground beetle species are efficient slug hunters), provides cover for wild animals, collects nitrogen, binds CO2, builds up humus and stores water in the soil. If the catch crop can be sown directly after the main crop using the appropriate technology, this saves labour, machinery and energy costs.
A relatively new option is to sow catch crops before the main crop is harvested using drones. The catch crop can then develop immediately after the harvest. The winter cereals are then sown directly into the standing catch crop mixture using a suitable direct sowing technique. This also saves a lot of time, costs and energy. In addition, the catch crop keeps the field clean - there are virtually no weeds. After cultivation, the catch crop lies depressed on the field and provides good cover, suppressing weeds and conserving water in the soil. The only thing to watch out for is volunteer plants from the previous crop. However, a very simple and inexpensive treatment in autumn is usually sufficient here.
The required sowing technology is of course more expensive than conventional technology. That's why you should aim for shared machines or consider using contractors. The bottom line is that many operations are simply eliminated. In addition, the humus-building measures stabilise yields - especially during drought.
Requirements for the catch crop mixture
Legumes such as summer vetches and forage peas (Peluschken), but also field beans, are very important to ensure good cover by the catch crop. Although these species are slow to develop when young, they provide excellent cover later on and suppress weeds and volunteer cereals very well due to the heavy shading.
At the start of growth, it is therefore important to have other fast-growing species in the field to take over this task. Oil flax, rachis, phacelia, safflower, oil radish and sunflower have proved particularly effective here. Buckwheat would also be one of them. However, buckwheat can form seeds very quickly, which can germinate in the following main crop and thus cause problems. This makes further plant protection measures necessary. Mixture partners can also be sorghum, alexandrine clover or mustard. It is always important to cover the soil well and suppress volunteer seeds and weeds.
The proportion of summer vetch or forage pea should always be sufficiently high, as these contribute particularly to success. Due to the vegetation period required for both species, cultivation is recommended by the beginning of August at the latest. Later sowing often does not produce the desired results.
Important for the sowing time
It is always wet in the catch crop. This means that you have to use phases with sunny weather for sowing in autumn. And there is usually still a lot of dew on the field in the morning, which makes sowing more difficult. It works best from later in the morning until dusk. At night, you get problems with the water on the plants again. In autumn 2021, the conditions were perfect. In 2020, however, the wetness was a major challenge. Sowing was only possible after several days of frost. The lush catch crop mass also prevents the topsoil from freezing through quickly, as it acts as insulation. It is also important (as is usual with direct sowing) to drive slowly in order to place the seeds well and evenly deep and to close the seed slot well. Direct sowing also causes far fewer weed seeds to germinate, which in turn saves on crop protection costs.
Adaptation of fertilisation
The many plant residues lying on top represent a barrier for solid fertilisers. This is especially true in dry conditions. In order to get the fertiliser to the roots in good time, the Cultan method should be used - unless some fertiliser can be placed right at the start when sowing. In dry years, the fertiliser lies on top when using the conventional method. It needs water to dissolve it and bring it to the roots. However, as the layer of dead plants also needs water and nitrogen to rot, the fertiliser is difficult for the roots to reach. As a result, the plants starve. This can lead to major yield losses.
With the Cultan process, the fertiliser is injected in liquid form and is immediately available to the plant at the root. It is injected into the root area in 32 small deposits per m2 using spiked wheels. At the beginning of May 2021 on my farm, I was able to see how light green winter poppies, some of which already had yellowish leaves, turned green again within three days thanks to this fertiliser and were really lush green after a week. And that in very cool temperatures, very dry conditions and on poor soil. Cultan fertilisation is therefore the perfect complement to the Planting Green method. Needless to say, both the catch crop and the Cultan fertiliser significantly reduce the amount of nitrogen required for the main crop.
Vision for the future
According to the official figures, our products such as wheat, maize and other crops can currently not be produced in a climate-neutral way. However, if we combine direct sowing with biodiverse catch crops and Cultan fertilisation with the corresponding benefits in terms of CO2 savings and plant protection, we should be able to achieve climate-neutral (or perhaps even climate-positive) arable farming. This theory is also supported by scientific calculations on greenhouse gas balancing: fewer agricultural crossings, lower input costs and at the same time higher CO2 sequestration make for a very favourable balance. This should of course be reflected both in product prices and in any payments to farmers for CO2 sequestration.
Conclusion
Direct sowing in green catch crops can help us adapt to climate change in many ways. The soil is always covered. This protects against heat, promotes soil life, prevents erosion, stores water in the soil and promotes humus formation. At the same time, the system brings us closer to our climate and biodiversity goals. In combination with Cultan fertilisation, CO2 and pesticides are also saved.
Too good to be true?
You might think: That sounds too good to be true. And yes, the system does not work overnight. It sometimes requires strong nerves and, above all, perseverance. But it's worth it!
So why not give it a try on one of your fields?