A review of ten years of trials on integrated crop protection systems: weeds can be controlled using techniques other than herbicides.

The challenges we face today with respect to food security and protecting the environment require the maintenance of high levels of agricultural production while using the lowest possible levels of inputs. Using the integrated crop protection systems being tested by INRA on the Epoisses Experimental Farm near Dijon, it has been shown that it is possible to achieve weed control with only a limited use of herbicides.

Culture de maïs semences (environs de Riom). © VIDAL Louis

Ten years of trials on integrated crop protection systems

Long-term systemic experiments at the Epoisses Experimental Farm near Dijon started in 2000. Alongside a traditional system, these experiments comprise four different cultivation systems: an integrated protection (IP) system without tillage, an IP system without mechanical weeding, a typical IP system, and a herbicide-free system. IP is based on a combination of weed management levers, which include the diversification of crop sequences; for example, the introduction of spring crops (barley, sunflower, soybean, maize, sorghum and lupin) and cover crops (triticale), in addition to the rapeseed, wheat and winter barley that compose the rotation in the reference system.  The management of soil tillage to deal with soil seed stocks, the avoidance of weed emergence by adjusting crop sowing dates, the choice of competitive varieties and mechanical weeding, are the other levers mobilised under IP strategies.

Satisfactory control of weed infestations

The results obtained during the ten years of trials have indicated that the levers tested can enable a satisfactory control of infestations while at the same time markedly reducing dependence on herbicides and their associated environmental impacts. The results concerning greenhouse gas emissions or energy consumption have remained satisfactory, with levels even lower than those reached using the reference system, thanks to the diversification of crops to include legumes that do not require nitrate fertilisation.  However, IP strategies mean a greater complexity of systems, and the implementation of some weed management levers is problematic in practice, notably in terms of the organisation of work at a farm scale.  Note has also been made that the IP systems under trial cause a slight reduction in economic profitability (of about -€100/hectare in a context of average prices), mainly linked to the poor yields of the "diversification" crops incorporated in the systems. These results thus underline the importance of crop diversification to the collective dynamic of reducing pesticide use.

These innovative cropping systems have aroused the interest of farmers and actors in agricultural development.  Numerous groups of farmers and consultants have visited the experiments and were able to see in the field how weeds could be controlled in systems involving very little use of herbicides.

What now for these experimental systems?

The experiments are being pursued in order to verify whether the trends observed in terms of weed communities (through the breeding of species better adapted to integrated protection) will not constitute a risk of a loss of control over infestations in the longer term.  In addition, it is planned to broaden the range of assessment criteria for these systems, notably by measuring their effects on biodiversity (earthworms, ground beetles, soil microflora, etc.) and on the transfer of pesticides to ground water.  Finally, during the past few years, the scientists have been seeking to evaluate the potential of strategies involving direct drilling under cover, so as to reconcile a reduction in herbicide use, the control of weed infestations and improvements to the energy balance.

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Associated Centre(s):
Dijon