Root cutters: Novel tillage methods to control creeping perennial weeds with a low risk of soil erosion and nutrient leaching

Abstract

Abstract Perennial weeds are a major obstacle for reducing pesticides and tillage. Three multi-year experiments were conducted in Norway and Sweden to determine if a) the horizonal and vertical root/rhizome cutters (HRC and VRC, respectively) can provide effective non-chemical control of multiple perennial weed species comparable to more intensive tillage methods (Experiments 1–2), b) without increasing the risk of soil erosion and nutrient leaching (Experiment 3), and c) if integrating the VRC with the HRC, mowing or disc harrow can increase the efficacy against perennial weeds (Experiment 1). All treatments were spring plowed in Experiment 1 and 3, and autumn plowed in Experiment 2. In Experiment 1, the rotary tiller was the most suppressive against Sonchus arvensis and Elymus repens but increased Stachys palustris shoot numbers. HRC treatments were not significantly worse than the rotary tiller and increased crop yield by 28%, reduced total perennial shoot biomass by 46–51% and reduced S. arvensis and E. repens shoot biomass by 52% and 80%, respectively, compared to an untreated control. In Experiment 2, HRC treatments reduced Cirsium arvense shoot numbers by 71% compared to the untreated control but failed to control E. repens. HRC treatment depth (7 vs. 15 cm) did not significantly affect control efficacy. Experiment 3 showed that HRC did not increase soil, water or nutrient losses compared to the untreated control and resulted in 60% less soil and 52% less phosphorous losses than disc harrowing. Treatments with VRC reduced the shoot biomass of E. repens by 40% and S. arvensis by 22%, compared to without VRC. Novelly, the results show that in plowed systems, HRC provides control of multiple perennial weed species that is comparable to more intensive tillage methods, but with little risk of soil and nutrient losses; and integrating VRC into control strategies improves perennial weed control efficacy.