Diversified grain-based cropping systems provide long-term weed control while limiting herbicide use and yield losses

Abstract

Integrated weed management encourages long-term planning and targeted use of cultural strategies coherently combined at the cropping system scale. The transition towards such systems is challenged by a belief of lower productivity and higher weed pressure. Here, we hypothesize that diversifying the crop sequence and its associated weed management tools allow long-term agronomic sustainability (low herbicide use, efficient weed control, and high productivity). Four 6year rotations with different constraints (S2: transition from reduced tillage to no-till, chemical weeding; S3: chemical weeding; S4: typical integrated weed management system; S5: mechanical weeding) were compared to a reference (S1: 3-year rotation, systematic ploughing, chemical weeding) in terms of herbicide use, weed management, and productivity over the 2000-2017 period. Weed density was measured before and after weeding. Crop and weed biomass were sampled at crop flowering. Compared to S1, herbicide use was reduced by 46, 65, and 99% in S3, S4, and S5 respectively. Herbicide use in S2 was maintained at the same level as S1 (− 9%), due to increased weed pressure and dependence to glyphosate for weed control during the fallow period of the no-till phase. Weed biomass was low across all cropping systems (0 to 5 g of dry matter m −2) but weed dynamics were stable over the 17 years in S1 and S4 only. Compared to S1, productivity at the cropping system scale was reduced by 22% in S2 and by 33% in S3. These differences were mainly attributed to a higher proportion of crops with low intrinsic productivity in S2 and S3. Through S4's multiperformance, we show for the first time that low herbicide use, long-term weed management, and high crop productivity can be reconciled in grain-based cropping systems provided that a diversified crop rotation integrating a diverse suite of tactics (herbicides included) is implemented.

The Pitfalls of Relating Weeds, Herbicide Use, and Crop Yield: Don't Fall Into the Trap! A Critical Review

“…without looking at weeds (Deytieux et al, 2012;Giuliano et al, 2016), implemented in single sites or multi-site networks (Deytieux et al, 2016). Few experiments monitored weed floras (Chikowo et al, 2009;Debaeke et al, 2009;Adeux et al, 2017Adeux et al, , 2019aJernigan et al, 2017) and even fewer assessed weed-driven yield loss, for instance by comparing yield in weedy and weed-free (manually weeded) zones (Teasdale and Cavigelli, 2010;Adeux et al, 2017). This lack of monitoring results in a high risk of confusing effects ( Table 4A).…”

Combination of Herbicide Band Application and Inter-Row Cultivation Provides Sustainable Weed Control in Maize

“…The first important factor is crop rotation, indeed CAB Massari farm adopts a diversified rotation including among others silage maize, winter wheat, sunflower, sugarbeet, and silage barley. Alternating spring and autumn crops in a multi-year rotation has been reported to reduce weed density in different cropping systems and environmental conditions [24][25][26]. With high weed density infestations, the preventive adoption of control tactics that reduce weed populations, such as stale seedbed or a diversified crop rotation, would be useful before the introduction of herbicide band application.…”

IPSIM-Cirsium, a Qualitative Expert-Based Model to Predict Infestations of Cirsium arvense

“…The complete description of the long-term cropping system experiment (crop sequence and associated management, including intensity of tillage herbicide, use herbicide types, mechanical weeding, etc.) implemented from 2000 to 2017 was synthesized by Adeux et al (2019). The reference cropping system (CS) called S1 was characterized by a 3-year oilseed rapewinter wheat-winter barley rotation, systematic moldboard plowing in summer-autumn and herbicides as sole curative weed management tool.…”