Date Published: February 7, 2019
Publisher: Public Library of Science
Author(s): Christian Frasconi, Luisa Martelloni, Daniele Antichi, Michele Raffaelli, Marco Fontanelli, Andrea Peruzzi, Paolo Benincasa, Giacomo Tosti, Pirjo Mäkelä.
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.
Cover crops are used in conservation systems to protect the soil from erosion, enhance water infiltration and storage, reduce nutrient losses through surface run-off or leaching, supply biologically fixed nitrogen, improve soil physical structure, increase organic matter content and compete with weeds, reducing the reliance on herbicides [1, 2, 3, 4, 5]. High biomass production is essential to ensure the maximum provision of such benefits from cover crops . There are many cases in the literature where the cover crop is terminated prior to planting the cash crop . The cover crop residues remain on the soil surface and act as a mulch that suppresses the weeds, also protecting the soil from rapid desiccation and keeping the soil moisture at good levels for cash crop seed germination or plant establishment .
The use of roller crimpers in combination with flaming for terminating cover crops improved the effect of the roller crimpers used alone, and more importantly, shortened the time needed to achieve cover crop desiccation compared with rollers used alone. This is very important in order not to excessively delay the time needed for sowing/transplanting the cash crop. Flaming combined with roller crimpers could therefore be used as an alternative to chemical herbicides in all agricultural systems where the latter are forbidden or intended to be reduced.