There is a need for more sustainable agricultural production, e.g. farming systems that maximize yield while minimize ecological impacts. In cereal production, two important aspects are (i) cover crops to e.g. prevent erosion and leaching, and (ii) new weed control methods that minimize herbicide and tillage use. Perennial weeds (e.g. Cirsium arvense, Sonchus arvensis and Elymus repens) are difficult to control without the use of glyphosate in conventional systems and without intensive tillage in organic systems. However, the future of glyphosate is in doubt due to regulation and intensive tillage increases the risk of soil and nutrient losses. SUSWECO’s goal is to develop new measures and strategies against perennial weeds in wheat without intensive soil tillage and minimal herbicide use.
SUSWECO’s main objective is to learn about the long-term effects of cover crops and low-intense tillage on grain yield, weed control and soil structure. Central to this is the continuation of a spring cereal trial in Norway that started in 2019 (the Long-Term Exp.). Results from the experiment have so far shown that it is possible to combine cover crops (perennial ryegrass and clover spp.) and low-intensity tillage when using the Root-cutter (a prototype tool with minimal soil disturbance). However, spring ploughing is necessary to obtain satisfactory control of all perennial weed species and also to kill the winter hardy cover crops without glyphosate.
For optimizing treatments in the long-term exp., we started two new field experiments: (i) One with different cover crop seed mixtures in combination with root cutter (+/-). (ii) Another with different numbers of root cuttings (0;1;2) at different soil depths (8 and 16 cm). Preliminary results from 2024 indicate a better effect of root cutting on E. repens than on S. arvensis.
Until now, no studies have been carried out in winter cereals including combination of cover crops and root cutting. In SUSWECO, during autumn 2024, multi-year experiments were established in Sweden and Norway with cover crop mixture (white clover/Persian clover/black medic) and root cutting. The trials will continue 2025-2026 with new applications of the different treatments between harvest and sowing of the new winter wheat crop. A second experiment with the same design was established in Sweden in September 2025. In Norway, a rotation trial (2024-2027) was started in 2024, which includes spring grain vs. winter grain, cover crops and root cutting.
In a field trial we test if new ‘bioherbicides’ and tools can kill both weeds and overwintering cover crops before spring sowing. Preliminary results show that ‘bioherbicides’ had poor efficacy, while strategies with harrowing could halve the amount of cover crops and E. repens.
As part of machine vision developments to enable spot weeding of perennial weeds in cereals with cover crops, and thereby reduce risk of herbicides and mechanical weeding, drone imagery (DJI Mavic 3 Multispektral) was collected before harvest at low altitude (12 m).
SUSWECO is also measuring the energy consumption of root cutting and ploughing. Measurements of energy consumption (4 experiments) have been made in collaboration with the Julius Kühn Institute in Germany. Preliminary results showed approx. 30-40% reduction in diesel consumption for root cutting vs. ploughing.
In the Long-Term Exp. soil strength measurements and soil samples were taken for aggregate size distribution and stability analysis after five years (autumn 2023). The soil strength measurements with a penetrometer clearly showed lower penetration resistance in ploughed than in unploughed plots. The penetration resistance was twice as high in unploughed plots where the weeds were controlled chemically or with cover crops compared to corresponding ploughed plots. The difference was smaller in plots with mechanical weed control. Aggregate size distribution and stability according to the rain method were determined in the laboratory. Aggregate stability was higher in plots with cover crops or with less intensive mechanical weed control (root cutter) that were not ploughed (vs. ploughed plots). A similar trend was found for several treatments. Ploughing also tended to result in more large aggregates (over 20 mm) less of the desirable aggregate sizes (0.6 to 6 mm). The difference was greatest where no mechanical weed control was carried out.
In a weed biology study, we showed that C. arvense mainly sprout from the intact root systems, and T. farafara from root fragments.
SUSWECO is coordinated by Norwegian University of Life Sciences. It is funded by Forskningsmidlene for jordbruk og matindustri and the project partners Kverneland Group AS, Felleskjøpet Agri and Myhres Maskinomsetning. Inland Norway University of Applied Sciences, Norwegian Institute of Bioeconomy Research, Norwegian Agricultural Extension Service, Swedish University of Agricultural Sciences and Research Institutes of Sweden participate.
Perennial weeds cause major concern in both integrated and organic cereal production due to risk of yield reductions. Control of perennial weeds is primarily done by intensive tillage in organic farming, whereas conventional farming for decades has relied on herbicides as glyphosate, particularly in reduced tillage systems. Glyphosate can soon be restricted or even banned in EU and Norway.
Project SUSWECO will develop new weeding tools and strategies for control of perennial weeds in cereals without or with minimized use of herbicides or intensive tillage. Novel tillage tools. root cutters, that cause minimal soil disturbance will make it possible to combine use of subsidiary crops and mechanical weed control. We will test if bioherbicides (e.g. pelargonic acid) and a specially adapted harrow can be parts of strategies killing both subsidiary crop and weeds before new crop is established.
Site-specific weed management (SSWM) can significantly reduce environmental loads of uniform chemical and mechanical weed management by applying control measures only at the weed patches in the field. The project will work on machine vision enabling site-specific management of perennial weeds in cereals with subsidiary crops.
We will also assess impact on soil quality and energy consumption of selected strategies. We will communicate with end users and stakeholders during project. New knowledge will be disseminated nationally and internationally.
SUSWECO is coordinated by Norwegian University of Life Sciences (NMBU). It is funded by Forskningsmidlene for jordbruk og matindustri and the collaborative partners Kverneland Group AS, Felleskjøpet Agri and Myhres Maskinomsetning. Inland Norway University of Applied Sciences (INN), Norwegian Institute of Bioeconomy Research (NIBIO), Norwegian Agricultural Extension Service (NLR), Swedish University of Agricultural Sciences (SLU) and Research Institutes of Sweden (RISE) also participate.
