Diverse cropping systems

Key learning outcomes

  • Understand the contribution of crop establishment date in driving the weed species and densities 
  • Understand the role that crop choice can have in aiding or inhibiting control of weeds 
  • Be able to use these two concepts together to develop a diversified rotation


At the heart of any IWM strategy should be a diversified rotation – making use of autumn and spring cropping, and different crop types, to reduce the over-arching weed burden. This module will describe the role in which diversity in crop establishment has for weed management, and how this can be practically applied to deliver meaningful weed control.

Training session

Using diverse cropping systems in weed management

This is a presentation developed by Philippe Delval, ACTA, France. The video is about nine minutes long. Additional notes, comments and links to additional content are given below the presentation.

  Music by Anton_Vlasov from Pixabay

Comments, notes and resources referenced in the video

  • Cultivation techniques : e.g. stale seedbed technique, sowing dates and densities, under-sowing, conservation tillage, pruning and direct sowing
  • Use of resistant/tolerant cultivars and standard/certified seed and planting material  where appropriated
  • Use of adequately balanced practices of fertilisation, liming and irrigation/drainage
  • Hygiene measures (e.g. by regular cleansing of machinery and equipment)
  • important beneficial organisms (e.g. by adequate plant protection measures or the utilisation of ecological infrastructures inside and outside production sites)

    These measures are to be implemented according to the culture cycle

  • Limiting pest initial population = Forms of conservation allowing management of infestations and primary inocula of pests
  • Avoiding attacks = Avoid the concordance between the phase of contamination of the pest and the period of sensitivity of the culture
  • Relieving the pressure = Minimize damage when the crop and the pest are in contact
    • Combination = Each method in itself is often insufficient to control a pest
    • Basics = IPM is doomed to failure if preventive methods are not implemented
    • Economical in inputs = Success depends on complementary methods and not substitutions

    IWM tool = Selection of preventative measures


      By diversifying crops (alternating host and non-host plants) and the dates or conditions of establishment that result from them, rotation can disrupt the cycle of pests.

      Cultural practices - Breaking of pest cycles over time: Rotation

      Adapting the succession and the cultivated species according to the health risks

      Rotation is the temporal organization of cultivated species on fields of an entire farm. This temporal distribution can have an influence on the conservation of crop enemies, especially when they have long and polyphagous capacities (ability to develop in or on several crops) by reducing infestations and to avoid specialization of the flora.

      Choosing diversified crops in the rotation

      Choosing diversified crops for a rotation makes it possible to vary the botanical families of the cultivated species, the type of rooting, the habit, the technical itineraries and thus to lengthen the period of return to the same crop. Thanks to this rotational measure, the negative impact of some pests can be reduced.

      Adapting cultivated species to the pedo-climatic context

      The choice of species to sow or plant in a cropping system is crucial and the pedo-climatic context must be considered first. A good adaptation of the cultivated species to the soil and to the climate will allow rapid implementation, will limit any unnecessary stress and will place these species in good conditions to resist crop enemies.

      Diversifying the periods of planting in the rotation

      In a rotation, it is interesting to vary the timing of planting, in order to break the cycles of pests. Thus, we can alternate autumn sowing with spring sowing, but also early sowing and late sowing.


    IWMPRAISE Inspiration Sheet : This IS discusses a traffic-light system technic of rotation with cereals developed by NIAB: Rotations and weeds in the UK

    IWMTOOL one factsheet is dedicating on describing rotation

    Designing a diverse crop rotation and/or specifically timing of the rotation can help to manage weeds, and prevent weed species from becoming dominant

    The changes to rotations videos are displayed further down this page


    Setting up cover plants in intercropping

    Intercropping is the period between harvesting one main crop and sowing the next crop. Intercropping cover, also called cover crops, are plants cultivated in this period to produce different agronomic and ecosystem services.

    Introducing a covering and cleansing crop into the rotation

    Introducing a cover crop in the rotation limits the development or emergence of weeds by their ability to develop rapidly, to cover the soil well and to exercise strong competition for resources (light, nutrients, water).

    Mechanically destroying intercrop cover plants and meadows

    It is possible to mechanically destroy a cover crop or a meadow, rather than using glyphosate in particular. Grinding, scalping, rolling, stubble cultivation, ploughing, allowing to freeze, as many techniques as specific conditions


    IWMTOOL one factsheet is dedicated to describing cover crops

    Cover crops are defined as all subsidiary crops that are grown in between main crops to cover the soil that otherwise would have been bare or covered with spontaneous vegetation.

    IWMPRAISE Inspiration Sheet : IWMPraise Italian colleagues have developed an IS defining  cover crops and subsidiary crops and their use for crop diversification.

    Crop diversification through the use of intercrops and subsidiary crops

    IWMGAME [arable crops] : one card represents implementation of cover crops. Cover crops have preventative and curative effects. You can play this card during the intercropping period and this method has beneficial side effects.


    Diversification of the cropping systems allows diversification of the weed management practices that will affect the weed species differently. Also other processes and interactions influenced by the diversity of the cropping system can benefit the crop and weed control. Weed control tactics based on diversification of cropping systems here are divided into diversification in time (cover crops and crop rotations) and diversification in space (intercropping, landscape arrangement and field margin management).


    Associations of species and cultivars = Genetic diversity limiting epidemics

    Associating trees with other species to diversify a crop (agroforestry)

    The association of trees with other cultivated species makes it possible to diversify crops while providing refuge areas and food resources for many organisms. Agroforestry is a concept of sustainable management of cultivable land which has many advantages for integrated protection.

    Combining several cultivated species to diversify a crop

    Associations or mixtures of species, by causing genetic diversity, in some cases limit the impacts of parasitic epidemics but also limit the development of weeds and resist lodging. They can also in certain cases play a role of refuge vis-à-vis the beneficial organism populations.

    Combining several cultivars of the same species to diversify a crop

    Associations or mixtures of varieties, by causing genetic diversity, make it possible in certain cases to limit the impacts of parasitic epidemics.

    Combining cover / companion plants to diversify a crop

    Companion plants that are grown in conjunction with cash cultivation are referred to as "cover crops associated with cultivation".

    They are sown before (under cover of the previous crop, at the harvest of the previous crop or in intercrop) or during the establishment of the crop of interest (at the same time as the sowing of the main crop or after it. ). This is intended to accompany the main crop by covering the ground during its first cycle of development, without competing with it afterwards.

    IWMGAME [arable & perennial crops]: one card is represented this measure. It have preventative and curative effects competing weeds. It concerns only inter-row in perennial crops to avoid competition on the row with the crop. You can play it at the first stage period and this method have benefit side effects. This method is no effective on perennial weeds.


    Practicing ground-covering of perennial crops: inter-row, below the row or total

    Ground covering has a main role which further limits the use of herbicides. In some cases, it can also help control pathogens by removing excess water on the ground. It also has many other advantages (limitation of vigor, improvement of the soil, etc.).

    Mechanically managing the row-cover of perennial crops

    Ground covering of perennial crops must be regularly maintained in order to control the risk of the development of undesirable weeds. This maintenance can be carried out mechanically using mowers or mulchers.

    Our Spanish colleagues have created  an IS sheet looking at cover crops in olive orchards

    Cover crops in olive-field trials of southern and northern Spain 


    IWMTOOL: One factsheet is dedicated to intercropping

    Intercropping is a way to increase the spatial crop diversity in agroecosystems, allowing optimized resource use and weed control at crop rotation level or in perennial crops.

    IWMGAME [perennial crops]: three cards represent this measure. It have preventative and curative effects competing weeds. You can play it during the intercropping period and this method have benefit side effects. This method is no effective on perennial weeds.

    One more card concerns the management of covers. It is important to control competition with the crops.


    IWMGAME [arable crops]:  One card represents this measure. It has only preventative effects avoiding weeds to develop on the field margin to invade the field later. You can play this card during the intercropping period and this method have no side effects. This method is not effective on perennial weeds.

    IWMTOOL: One factsheet dedicated to describing field margin management

    Grassy field margins, wildflower strips and beetle banks can boost the abundance of seed-eating carabids in the adjacent crop.

    A second factsheet is dedicated to describing landscape arrangement

    An increasing amount of natural habitats surrounding agricultural fields enhances weed diversity, because they may function as a source of propagules for colonising fields.


    Tolerating the presence of useful and uncompetitive weeds
    The purpose of weed tolerance is to avoid the use of herbicides. Their presence can improve the structure of the soil through their root system and can promote the presence of beneficials and pollinators within the cultivated field.
    It is possible to accept and control the presence of certain species of useful weeds in the plots, therefore, to allow them to develop, or even to introduce them if they are not historically present in the plots concerned. The choice of weeds to maintain depends both on their usefulness for the maintenance of auxiliary organisms, pollinators or other species and on their low competitive power toward the crop.

    Spring cropping: how it works

    A presentation by John Cussans, NIAB, Cambridge, England. The video is about five minutes long.

    Spring cropping: in detail

    A presentation by John Cussans, NIAB, Cambridge, England. The video is about fourteen minutes long.