Targeted timing of hairy vetch cover crop termination with roller crimper can eliminate glyphosate requirements in no-till sunflower

Abstract

No-till cropping systems with cover crops can improve soil health, but often rely on glyphosate, which is a contentious herbicide. In this study, we investigated whether a system based on the direct sowing of sunflower (Helianthus annuus) in the dead mulch of a roller-crimped hairy vetch (Vicia villosa) could be competitive with a system where glyphosate is also sprayed to terminate the cover crop and to control weeds. We hypothesized that optimum timing of roller-crimping would be key to eliminate glyphosate requirements while maintaining sunflower performance. In a 3-year on-farm experiment, we compared three vetch termination stages (early: pre-flowering; Intermediate: beginning of flowering; late: 70% flowering) and three glyphosate rates (Nil, half and full, i.e. 1440 g of active ingredient per hectare). Vetch biomass increased progressively from early to late termination stages, and ranged between 414 and 658 g m−2. Higher vetch biomass was correlated with lower weed biomass. Treatments had inconsistent effects on weed diversity and composition, largely determined by the interactions between treatments and seasonal (different years) or local factors (different fields). Glyphosate-based treatments seemed to select for aggressive weed species, but no clear species filtering effect based on ecological or functional traits was detected. Shannon H’ was positively correlated with sunflower grain yield below a weed dry biomass threshold of 150 g m−2. Crop yield with early termination stage was a failure without glyphosate application. However, crop yield with late vetch termination was acceptable, being at par or 15% higher (mean of first and second years) in no-glyphosate compared with glyphosate-based treatments. Crop gross margins showed the same trend (+33% for no-glyphosate compared with glyphosate-based treatments). This study, for the first time, shows that targeted timing of roller-crimped hairy vetch in no-till sunflower can result in equal agronomic and economic performances as addition of glyphosate.

Current and future glyphosate use in European agriculture

“…Alternatively, cover crops can be killed by winter frost in cold‐temperate regions or actively destroyed through mowing, roller crimping, or other herbicide applications. Roller crimpers have emerged as a sustainable approach to terminate cover crops and create natural mulch in reduced tillage systems (Antichi et al, 2022; Kornecki, 2020). The discussion around tillage versus roller crimper approaches has attracted interest in Europe (Navarro‐Miró et al, 2019), yet detailed research is needed to assess the effectiveness of prototypes across different soil textures, moisture conditions, and biomass levels, aiming to improve the tool and broaden its applicability (Sportelli et al, 2023).…”

The Potential of Cover Crops for Weed Management: A Sole Tool or Component of an Integrated Weed Management System?

“…However, this may not be the case for crop productivity in perennial cropping systems but there are very few studies showing the effect of the cover crop termination method on crop productivity. For example, in an annual crop system in central Italy, a study compared the termination of cover crops at different times with a roller-crimper and glyphosate applications and observed that the sunflower ( Helianthus annuus ) yield was similar between the two systems when the cover crop was rolled late but not when it was rolled at an earlier stage of the cover crop and hence, the authors suggested that early termination of cover crops with a roller-crimper may have to be combined with glyphosate applications [ 41 ]. A study compared the chemical, mechanical, and chemical + mechanical termination methods of cover crop termination and their effect on cotton ( Gossypium hirsutum ) emergence and yield, and reported some differences in the crop emergence but no effect on yield [ 42 ].…”

Agronomic performance of disc chain harrow as a conservation agriculture tool for a one-step cover crop termination and seedbed preparation

“…Together with species choice, seeding rate, and sowing date, the plant devitalization date and modality are crucial aspects of cover crop management (Antichi et al , 2022; Benincasa et al ., 2010; Delgado and Gantzer, 2015; Thorup-Kristensen et al , 2003), since they affect the magnitude of the above-mentioned benefits and, in addition, the nutrient availability for the next crop, the soil moisture, the timeliness of the following cash crop plantation, and the success of its establishment. Finally, the modality of cover crop termination may affect fuel consumption (per unit time and unit area), the working speed, and the traction force required, with implications on the tractor needed and on farm management and logistics.…”

“…Several alternatives have been proposed, aimed at reducing tillage depth and increasing crop stubbles on soil surface, up to leaving a dead mulch covering the soil, which is considered the cornerstone of soil conservation management in organic cropping systems (Stagnari et al , 2009; Vincent-Caboud et al , 2019). Among these, we can mention several mechanical treatments like harrowing, hoeing, strip tillage, and roller crimping (Antichi et al , 2022; Benincasa et al , 2017; Creamer et al , 2002; Kornecki et al , 2009; Stagnari et al , 2009; Trevini et al , 2013). In particular, with the use of roller crimper, plants remain anchored to the ground forming a thick dead mulch which, while degrading very slowly, provides soil protection and prevents weed growth (Ashford and Reeves, 2003; Mirsky et al ., 2009).…”

“…In particular, with the use of roller crimper, plants remain anchored to the ground forming a thick dead mulch which, while degrading very slowly, provides soil protection and prevents weed growth (Ashford and Reeves, 2003; Mirsky et al ., 2009). The roller crimper can be used either alone or in combination with chemical or thermal treatments, e.g., herbicides (such as glyphosate) or flaming (Antichi et al , 2022; Ashford and Reeves, 2003; Frasconi et al , 2019; Price et al , 2009). Anyway, seedbed preparation after roller crimping generally needs a subsequent soil tillage, at least along the furrow where the seed will be laid.…”