Min-till even without glyphosate: Is ‘shallow and flat’ the future?

Since 2021 the Kerns must work without glyphosate in water protec­tion areas. For a cultivation system without ploughing this means extra work and increased risk of erosion. The extra cultivation required per crop not only increases diesel consump­tion, but also stim­u­lates the soil to miner­alise. The process breaks down humus and releases nutri­ents, which are then at the mercy of leaching. “So, I’m doing every­thing I don’t really want to do right now. But I have no choice,” says Alexander. This is precisely why the farmer and master butcher attaches so much impor­tance to catch crops and conser­va­tion tillage. In 2019, he also adopted the prin­ci­ples of regen­er­a­tive agri­cul­ture.

Some farmers who have worked the soil without ploughing for many years have been inten­si­fying tillage again since 2021. The ban on the herbi­cide glyphosate in healing spring and water protec­tion areas – and as a late appli­ca­tion before harvest under the Order on the Use of Plant Protec­tion Prod­ucts (PflSchAnwV) 2021 – is to blame. “In certain crop rota­tions, nitrate levels are there­fore rising again in water protec­tion areas in the Karl­sruhe district,” says Rolf Kern, crop produc­tion adviser at the Karl­sruhe district office. Despite the restric­tions, this expert on crop nutri­tion, erosion and soil protec­tion considers minimum tillage to be possible, perhaps even the only sensible option. “I’m convinced that we can’t beat climate change any other way. Our soils need to become more resilient, and we can only do that without ploughing, as it depletes soil fertility and wastes water,” he explains. “Shallow and flat” is the motto of the future.

The Kern family’s work shows how it is possible to combine gentle tillage with catch crops to farm without glyphosate. Alexander values species-rich catch crop mixtures to protect against erosion. He wants to use the resulting good soil struc­ture for the following crop instead of destroying it by ploughing.

Cutting off freezing catch crops during frost

When the farmer realised that he would have to do without glyphosate, he invested in a 6m-wide flat culti­vator with a high produc­tivity (approx. 6ha/hr) and wide culti­vator coul­ters. This allows him to cut off catch crops and weeds 2-3cm below the soil. Thanks to the high area output, the oper­a­tors get through the neces­sary addi­tional tillage passes more quickly. “I can recom­mend this to everyone,” says the farmer.

Depending on the catch crop and main crop, he uses one of two methods to kill off the growth: The stan­dard method, which is used before most crops, or the surface rotting method before late crops. In the stan­dard method, the freezing catch crop is crushed with a blade roller during a frost and then worked in with the shallow culti­vator, also during frost. “Chop­ping the catch crop in a frost is more successful than later cultivation with a culti­vator, disc harrow or shallow culti­vator,” explains Alexander. Phacelia and Niger seed (Guizotia abyssinica) can also be safely killed off with this method.

Chop­ping the catch crop in a frost is very successful

Alexander Kern

In prin­ciple, it would be suffi­cient to work the catch crop in with the field culti­vator during a frost. However, the barely crushed plant parts could then bung up the shallow culti­vator in the spring. Instead, as soon as the catch crop has been culti­vated, earth­worms take over to process the residues. And for Alexander, keeping as much mass as possible within the soil surface provides protec­tion against erosion and heat.

He then sows the following crop directly into the seedbed. His beet seeders have a mulch seeding system and the power harrow for the barley seed also passes through without any prob­lems.

Surface rotting before late crops

Before late crops like maize, Alexander adopts surface rotting – a proce­dure common to regen­er­a­tive agri­cul­ture which provides long soil cover. In this process, the over­win­tering catch crop is killed off in spring with a culti­vator or disc harrow, simul­ta­ne­ously shred­ding it with the mulcher. The longer the catch crop can grow before­hand, the better for the soil. The disad­van­tage: “If a catch crop stands for so long, you natu­rally have noxious weeds in it,” says Alexander. In maize, however, he is still allowed to use many herbi­cides to elim­i­nate grass weeds.

The rotary culti­vator is equipped with a tank for surface rotting, which makes it possible to spray effec­tive microor­gan­isms (EM) into the catch crop which has been cut off close to the ground. These are intended to ensure an effec­tive rotting process. For surface rotting, the soil needs a certain temper­a­ture: The soil life must be active. Cutting, chop­ping, and incor­po­rating the catch crop then take place in one oper­a­tion. “This is quite labour-inten­sive. You must drive slowly,” says the farmer. It would be easier with the disc harrow, but it cuts the catch crop less cleanly.

Depending on the weather, the surface rot remains in place for about one to two weeks. Before sowing the next main crop, only one more cultivation pass with the shallow culti­vator follows.

Even good plans can fail

So much for the theory. This year, the weather thwarted the Kern family’s plans. The over­win­tering catch crop was supposed to be worked in 2-3cm deep by mid-March. But it was not possible to travel until mid-April. To make matters worse, the catch crop had not grown well in the dry summer of 2022. Field foxtail and the previ­ously culti­vated rye did not miss this oppor­tu­nity and grew vigor­ously. So surface rotting is not an option this year.

But Alexander is not dissat­is­fied. After all, the catch crop sequestered nitrogen for eight weeks, revi­talised the soil and ensured green cover. “I had no erosion and could spread compost, fermen­ta­tion residues and manure in the growing crop in winter. That was what I wanted,” explains Alexander. In return, he now has to accept the weeds. “You just have to adapt,” he says. So this year he did not culti­vate the catch crop until shortly after Easter, cutting 8cm deep over the entire surface. About a week later, he took the field culti­vator through the remains of the catch crop, with a final tillage after another week, imme­di­ately before drilling the maize, at which point the grasses should have finally died off.

Grad­u­ally adapting tillage

Crop consul­tant Rolf advises farmers who want to reduce ploughing not to suddenly change tillage from one day to the next. “That doesn’t work,” he warns. Instead, it is better to proceed grad­u­ally and to combine the conver­sion with appro­priate crop rota­tion, inter­crop­ping and, where possible, under sowing. “With the help of the plants, you build up soil struc­ture and humus. The more humus-rich the soil becomes, the easier it is to work,” explains the soil expert.

For gradual adap­ta­tion, one could, for example, work 10-15cm deep with the field culti­vator for the first one to two years. After that, farmers could go less deep from year to year and then switch from the culti­vator to the disc harrow. About four years, it is then possible to work only shallow and flat.

Alexander is still unde­cided about how the glyphosate ban will affect his farm in the long term. “It may be that I’ll have to plough again in the future, although I’d need erosion protec­tion (because of the grass weed problem),” he ponders. For the moment, however, a farm without both ploughing and glyphosate seems feasible to him.

As an advo­cate of conser­va­tion tillage, Rolf is convinced that it is possible to work without glyphosate. Farmers who only culti­vate shal­lowly already have the neces­sary know-how and expe­ri­ence. “With more working time, more equip­ment, more wear and tear on machinery, more passes and more diesel, they can do it.”

Without investing in the right tech­nology, however, it would be hard to avoid going back to the plough, says Rolf – partic­u­larly if glyphosate can no longer be used. Alexander also swears by a wide range of ground-working imple­ments – despite the high fixed costs. This is because they enable him to react better to in-field condi­tions. The current long delivery times of machine manu­fac­turers, of six to 10 months, can there­fore delay the conver­sion to minimum tillage. But, Rolf adds: “Only by working shallow and wide can you get good weed and volun­teer cereal control without glyphosate and ploughing.”