INTERCROP

Intercropping of cereals and grain legumes in European organic farming systems

Intercropping, the simultaneous cultivation of more than one species or cultivaron the same piece of land, can increase organic cereal and grain legume proteinproduction in Europe, enhance biodiversity in European farming systems and safeguard the organic farmers’ earnings. Despite its advantages, intercroppinghas traditionally been neglected in research on plant production systems in temperate agricultural ecosystems, due to its complexity and because of the difficulties for its management and lesser relevance in cropping systems based onagrochemicals.

The INTERCROP project takes a unique multidisciplinary and integrated Europeanapproach to evaluate the potential of this technique and define intercroppingstrategies for sustainable plant production management in organic farming systems under different regional conditions in Europe.

Intercropping is defined as the growth of morethan one crop species or cultivar simultaneouslyin the same field during a growing season. It isthe practical application of ecological principlessuch as diversity, crop interaction and othernatural regulation mechanisms. Intercropping has many advantages, mainly related to thecomplementary use of environmental resourcesby the component crops which results inincreased and more stable yields, better nutrientrecycling in the soil, better control of weeds,pests and diseases and an increased biodiversity.Cereals and legumes, both for forage and forgrain, are the most common intercrops.The mainadvantage of the legume–cereal intercrop is theinput of nitrogen to the system by the fixation ofatmospheric N2 by the legume, which results inimproved use of renewable nitrogen sources.

Cooperation at the EU level

INTERCROP is composed by a multidisciplinaryteam of European scientists which work co-ordinately, conducting research on intercroppingand facilitating the exchange and synthesis ofexisting knowledge in order to make recommen-dations for using intercropping under differentregional conditions and farming systems.

INTERCROP objectives

The project’s core experiment is a field trial inwhich pea and barley are intercropped in withspring sowing and compared with the respectivecrops in pure stands.To compare the performanceof intercropping in organic farming situationsacross Europe, all INTERCROP partners haveestablished this experiment at organic sites usingthe same cultivars.

INTERCROP consists of six inter-related work-packages (WP) made up of tasks that involveseveral partners:

WP1. Survey and demonstration on-farmDuring 2004, almost 100 organic farmers acrossEurope were interviewed about intercropping.The survey of farms in different countries wasbased on a standard questionnaire coveringsubjects including farm structure, crop rotation,fertiliser use, plant protection methods and typeof intercrop.

In the summer 2005, on-farm demonstrationshave been carried out in order to increaseawareness and provide advice on intercropping,especially cereal–grain legume systems, inorganic farming.

WP2. Agronomic performance and yield stabilityIn the basic field trial, measurements such as leafarea index, dry matter production and grain yieldhave been taken each year by all partners inorder to determine the agronomic performanceof cereal-grain legume intercrops in terms ofyield advantage and to study the yield stabilitycompared with associated sole crops.At somesites, a series of extra designs within the basicfield trial have allowed for the collection ofadditional information about specific strategiesfor optimising the use of environmentalresources by the intercrop.

Intercropping for an increased production, weed control, improved product quality and prevention of N-losses

WP3. Nutrient acquisition, N loss and subsequent crop NTotal N acquisition and soil N have been determi-ned annually in the intercrops and sole crops inorder to estimate N balances, effects of intercrop-ping on post-harvest N dynamics in the soil andthe potential risks of N leaching.The N2 fixedfrom the atmosphere and taken up from the soilhave also been estimated using 15N isotope tech-niques. N accumulation in a following autumn-established cereal as influenced by the pre-crophas been determined and its economic effectsestimated.The acquisition of other nutrients suchas phosphorous, potassium and sulphur by theintercrop has also been monitored.

WP4. Intercropping for weed, pest and disease managementIn the basic field trial, pests and diseases havebeen monitored at the key physiological stagesof the crops and weed species, weed dry matterproduction and weed N content have also beendetermined every year.A glasshouse study onroot elongation of spring pea, spring barley,white mustard and rye grass was also conducted,based on the hypothesis that the reduced weedpressure often observed in intercrops is due toincreased root competition for nutrients.

WP5. Quality parameters in intercropped components and following cropsThe different interaction mechanisms that occurbetween plant species when intercropped aswell as the effect of the intercrop on thefollowing crop in the rotation might influencegrain quality.This has been studied bydetermining the effect of intercropping on aseries of quality factors, such as physical grainquality, ratio of nitrogen and sulphur concentra-

tions, protein quality of wheat for bread-makingand livestock feeding value of barley, wheat, peaand faba beans.

WP6. ModellingAn existing simulation model (STICS-monocrop)has been adapted for use with pea–barley inter-cropping with a special emphasis on nitrogenuptake by the crops.The parameterisation ofSTICS-intercrop has been based on a set of dataobtained from a basic pea–barley experiment inwhich crops were grown in optimal conditions.The model has been validated with a set of datacollected annually from the basic field trial by allpartners.The STICS-intercrop model is nowsuitable for use with different crops, various cropmanagement methods (including low inputfarming) as well as different pedoclimaticsituations.

Dissemination activities

All of the INTERCROP partners have successfullygathered the required data for each WP and thishas provided a wealth of interesting newinformation. During the duration of the projectpartners have been very active in the dissemina-tion of information about the activities beingconducted in INTERCROP.

Open field days to visit the different experimentshave been organized yearly at the different sites,partners have frequently given talks at popularand scientific levels, and scientific articles eitherfully or partially based on the results have alsobeen produced. Students have also been involvedat different levels.The project is also publicizedby presentation of posters at different congressesand symposiums.

INTERCROP is a three-year project funded by theEuropean Community under the 5th FrameworkProgramme of RTD, Key Action no. 5.1.1(Sustainable Agriculture – New and improvedproduction and farming systems).

Project durationThe project was initiated in January 2003 andwill finish in December 2005.

PartnersINTERCROP brings together scientists from eightinstitutions in Denmark, France, Germany, Italyand UK, who have complementary and inter-nationally respected expertise in differentaspects of the project, including crop ecology,plant nutritional physiology, nutrient cycling,grain quality, cropping systems research, cropmodelling and organic farming.

The partners are:

Denmark: Risø National Laboratory &Danish Institute of AgriculturalSciences.

France: Ecole Supérieure d’Agricultured’Angers & INRA Avignon

Germany: Kassel University.Italy: Università “Mediterranea” di

Reggio Calabria.UK: University of Reading.

Project coordinatorErik Steen Jensen, Biosystems Department, RisøNational LaboratoryPhone: +4546774108,e-mail: erik.s.jensen@risoe.dk

More information about INTERCROPIn November 2003 INTERCROP opened its ownwebsite (www.intercrop.dk).The site contains allthe project information and is updated frequent-ly with information concerning the project andpartners’ activities.

In May 2006, INTERCROP will participate in amajor organic congress to be held in Odense,Denmark.The congress will be held in collabora-tion with other EU funded projects.

Facts on INTERCROP

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