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Reducing the use of pesticides is possible!

Ten years of trials on Integrated Protection cropping systems

Weed flora can be controlled by techniques other than herbicides. © inra, UE Domaine
Updated on 01/22/2014
Published on 01/23/2013

Current challenges regarding food security and protection of the environment require continuing high crop yields while using the lowest possible level of inputs.  The declared objective of the Ecophyto 2018 plan to reduce pesticide use by 50% is ambitious, and can only be reached by significant modifications to current cropping systems.  Using the Integrated Protection (IP) systems tested by INRA Dijon at its Experimental Farm at Epoisses, results show that it is indeed possible to control weed flora while using few herbicides.

Ten years of trials for Integrated Protection cropping systems

Long-term systemic experimentation was initiated at Epoisses in 2000.  Five cropping systems are experimented in addition to the traditional system, and a few examples are : IP system with no tillage, IP system with no mechanical weeding, the typical IP system, and a herbicide-free system.  Integrated Protection is based on a combination of weed flora management techniques, among which is diversification of crop sequences, with the introduction of spring crops (barley, sunflower, soya, maize, sorghum, lupin) and cover crops (triticale), in addition to the traditional system of crop rotation composed of oilseed rape, wheat, and winter barley.  IP strategies also use tillage planning for managing seed stock in the soil, weed growth prevention by adapting crop sowing dates, choice of competitive varieties, and mechanical weeding.

Satisfactory control of weed flora infestation

Results obtained from 10 years of trials indicate that the above strategies can satisfactorily control weed infestation, while significantly reducing dependence on herbicides and its associated environmental impacts.  Results concerning greenhouse gas production or energy consumption remain satisfactory, and are even slightly lower than with the traditional system, thanks to crop diversification using legume crops which do not require nitrogen fertilization.  However, IP strategies involve more complex systems, and certain weed management methods are difficult to implement, notably by causing labour organization difficulties on the farm level.  Using the tested IP systems has led to a slight fall in farm income (of around -100€/hectare on average), due mostly to the low yields of diversification crops included in the system.  These results illustrate the importance of diversification in the overall effort to reduce pesticide use.

Farmers and farming industry stakeholders are attentive to these innovative cropping systems, and numerous farmers and farming advisors have visited the Epoisses site.  They have seen for themselves that weed flora can be controlled in systems using very small quantities of herbicide.

Where does the experiment go from here?

Experimentation goes on in order to verify that the observed trends regarding changes in the weed community, using selected species more suitable for integrated protection, do not lead to loss of control of weed infestation in the long term.  Also, the range of criteria for evaluating the systems will be extended, in particular measurement of effects on biodiversity (earthworms, beetles, soil microflora…) and on the seeping of pesticides into groundwater.  Scientists have been working for several years to evaluate the potential of direct covered sowing strategies in order to reconcile the reduction of herbicide use, weed infestation control, and improved energy performance.

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What is Integrated Protection?

Integrated Protection (IP) against weed flora is based on combinations of cropping techniques designed to reduce weed infestation in crops while reducing herbicide use.  This type of farming is often considered to strike a balance between intensive, high-input farming, and organic farming which prohibits the use of chemical inputs.  The idea is to use farm management methods that exploit physical and biological regulations in order to control pests by affecting different stages of their life cycles.  IP combines and promotes a number of alternatives to herbicides, which have partial but complementary effects.  However, IP is not opposed to the occasional use of chemical products when this proves necessary.

Typically, techniques are combined in order to :

  • Reduce infestation potential (seed stock in topsoil)
  • Avoid the growth periods for weed species : stale seedbed technique
  • Destroy weed plantlets that grow during the crop cycle, particularly by mechanical weeding
  • Limit weed growth

Taken individually, none of these techniques are as efficient as herbicides.  Thus they need to be combined in order to affect weed propagation in a coherent cropping system, and farmers need to be fully aware of the interactions between the techniques in order to exploit possible synergies.  Biological and physical regulations can be controlled by adapting farm practices, either for one crop year in a specific plot, or over several years in larger areas.