Combining roller crimpers and flaming for the termination of cover crops in herbicide-free no-till cropping systems

Abstract

The termination of cover crops in conventional no-till systems is mostly conducted mechanically in combination with herbicides. Combining flaming and roller crimpers could be a viable solution to avoid using herbicides for cover crop termination in farming systems where herbicides are banned, or at least to reduce their use in an integrated management approach. This research tested the effects of flaming used in combination with three different types of roller crimpers to terminate a fall-sown cover crop mixture of winter pea and barley. The cover crop termination rate was visually assessed in terms of percentage of green cover provided by cover crop plants at different intervals from the termination date, and estimated using a log-logistic non-linear regression model with four parameters. Machine performance data are also reported. The results show that, irrespective of the roller type, flaming significantly boosted the effect of the roller crimpers. In fact, an economic threshold for cover crop suppression of 85% was reached only when the rollers were used in combination with flaming. Nevertheless, none of the methods were able to reach the 100% of cover crop suppression. In some case, the combined use of flaming and roller crimpers allowed reaching the 90% of cover crop devitalisation, which happened six weeks after the termination date. More importantly, the use of flaming in combination with rollers shortened the time needed to achieve the estimated levels of devitalisation, compared with the rollers used alone. We conclude that flaming is an effective tool to increase the effectiveness of roller crimpers. Nevertheless, further research is needed to identify solutions to overcome the barrier of the high operational costs of flaming, which is constraining its wider adoption by farmers. Future studies could focus, for instance, on the development of a new prototype of combined machine for crimping and flaming the cover crops simultaneously, which could potentially reduce the operational costs.

Fig 1. Monthly (October 2014 –June 2015) and 30-year cumulated precipitation, and monthly average, maximum and minimum and 30-year average temperature recorded by the meteorological station at FieldLab in Papiano (Perugia, Italy) (42°57'22"N 12°22'32"E).

Fig 2. Monthly (October 2015 –June 2016) and 30-year cumulated precipitation, and monthly average, maximum and minimum and 30-year average temperature recorded by the meteorological station at FieldLab in Papiano (Perugia, Italy) (42°57'22"N 12°22'32"E).

Fig 3. The Fleco heavy roller.

Fig 4. The Clemens Eco-roll with the Hexagon frame and water container.

Fig 5. The Rodale Institute design-based roller crimper front-mounted at the New Holland TL100 tractor.

Fig 6. The flaming machine conducting cover crop mixture termination after the roller crimper operation.

Fig 7. Percentage of green cover as affected by time (days after termination) and by the interaction between the type of roller (Fleco, Clemens and Rodale) and the flaming factor (if applied or not), in 2015 and 2016 growing seasons.

All the data points and the model-based standard errors are reported, respectively, in the top and bottom graphs. The parameters of the curves (Eq 1) are reported in Table 2. Degrees of freedom: 96. The percentage of green cover before the termination was 100% in all plots.