Roberto Ruiz de Arcaute is a research technician for the Basque Research and Agrarian Developement Institute, as well as being one of our usual speakers in our training courses.

What is the relevance of weeds for crops?

Weeds make one of the main challenges for organic farmers. In horticultural crops, the possibility of using different kinds of mulching and, in fruit trees and grapeyards, the more and more usual use of vegetal covers between rows and the mechanization of work in the rows decrease the necessary work for their control. However, in extensive farming crops, the limit to physical or mechanical methods to weed control demands farmers an accurate control of rotation, a great attention to the land preparation before sowing and in the initial stages, and crop tracking during the first weeks after the emergency to decide whether to act with a weeding tool.


How can organic farmers ensure pest and illness control? What are the differences from a conventional one?

It is clearer and clearer that environmental biodiversity – increased either by the maintenance of diverse hedges on the edges or by the management of covers on fruit trees and grapeyards, thanks to the implementation of flower bands in horticultural crops or the shelter bands in extensive farms – is the guarantee for pest ranges to be kept under the damage threshold. On the other hand, soils health, being kept by means of appropriate main crop rotations and the addition of interstitial crops between them able to disinfect and as a provider of organic material to the ground, are key to crops health thanks to the interaction of soil microorganisms with the rhizosphere. If, despite prevention measures, farmers detect any problem to be likely to escape from control, they have available a number of authorised products to be used in organic farming, really efficient against those pests and illnessess which can reduce damage and performance looses.

The main difference from the convenional system is that, for any pest and illness control to be effective requires the farmer to foresee the problem by careful observation of the crop (vegetation growth, soil coverage, roots and collar state, presence of known pests individuals and/or biological control aids), and of the environment (mainly weather and ground) to value/estimate main problems to be faced, as in organic farming there is not an only ´recipe´ to solve problems as in the conventional system, organic system is so difficult that easy recipes don’t work.


Regarding fertilization What are the main aspects to be taken into account by organic farmers? What would you advice to optimize crop rotation?

Mainly that the ground scheme requires of organic material contributions to be kept healthy and active, and the most economic way to get this organic material is by means of rotations including fodders and green fertilizers. Besides, the N required for the development of crops can only be organic, so, either it comes froms biological fixation of soil microorganisms (mainly in leguminous spices) or it is supplied as an external input, (diverse composts), which can mean  a higher cost than the one of growing leguminous plants or other spices as fodders or green fertilizers. This is linked to the issue of rotations: paying attention only to extensive farms, it must be necessary to start the rotation sequence with leguminous plants and to take advantage of the following season to grow a quality cereal, always paying attention to weed management. Afterwards, an interstitial crop or a fodder, followed by a summer crop would be useful to break weed cycles and keep the farm as clean as possible from weeds. This would be the spirit to plan an appropriate  rotation sequence in extensive farms.


How can difficulties of seed management and lack of appropriate varieties to the sector  be dealt with?

Generally speaking, the behaviour of almost every current commercial varieties in organic farming is not known, as they have been assessed in conventional farming condition. For thirteen years assessment research on soft wheat in organic farming have been conducted by GENVCE, which in Aragon are managed by ARAX net, whose results, already published, may help farmers to choose among the analysed varieties. So far, the most highly renowned ones due to their results among organic farmers are local or a little old varieties, whose certified seeds, let alone organic certified seeds, are difficult to find. This is a concerning subject because the lack of productivity of organic crops can be partially due to the conditions in which reproductive materials are. For example, from time to time some wheat shipments have been found out to be affected by covered smut (a Tilletia fungus), which can neither be used for consumption nor as a reproductive material as they would pollute the grain batch as well as the farm where to be planted.

It is required to reflect on this situation, as even though the production of organic farming certified seeds increases every year, the new rules to become effective next January set a higher demand than the current one of the use of organic seeds, so it is necessary to get ready for that momento. European Commission has proposed the development of essays of high agronomic value in organic farming for different spices, whose results will be known from 2022 on. It is also going to be allowed to produce a new kind of reproductive material called ‘Organic Heterogenous Material’ (OHM), which, once in the hands of farmers, they will be able to multiply and commercialize it in the organic field. This kind of material does not exist in Spain yet, so it requires institutions and research centres to make an effort to promote its obtention and participative assessment, and the organic sector to keep up along this path.


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