Grain legumes and the environment
To determine the environmental impact of increasing the production and use of grain legumes in Europe, specific methods of measurement are required, some of which are not currently available. It was in this context that the international scientific workshop was organised in Zurich in November 2004 by AEP and Agroscope FAL Reckenholz, supported by the EU Concerted Action known as GL-Pro (‘European Extension Network for the Development of Grain Legume Production in the EU’, QLK5-CT-2002-02418).
The proceedings of this workshop have been recently published1 and they include 40 articles (225 pages), issued from talks and posters presented in the four themed sessions of the workshop: ‘Methodology for environmental assessment of grain legumes: state of the art’; ‘Grain legumes in crop rotations’; ‘Nitrogen cycle of grain legume crops’; and ‘Grain legumes in animal feeding’. They also include syntheses of the sessions, including the expert discussions arising from the workshop.
The workshop objectives were: to gather and exchange expert knowledge, to define knowledge gaps and future research needs and to establish an inter-disciplinary expert network of scientists working on environmental aspects of grain legume production and use. The emphasis was on the methodology required and most suitable for assessing the environmental consequences of increasing grain legumes in European agriculture.
The questions posed are complex and the discussions emphasised the added-value of interdisciplinary approaches and of complementing models with agronomic and physiological know-how to improve tools and analyses. The real challenge is for research to be carried out on different temporal and spatial scales, and at different process and systems levels.
The nitrogen cycle and underlying mechanisms need to be modelled in more detail. In crop production, the whole crop rotation or at least crop sequences must be considered. Investigating only an individual crop is certainly insufficient and may lead to wrong conclusions. Losses of nitrogen in the form of nitrate to ground water and nitrous oxide to the air related to the cultivation of grain legumes should be measured more accurately. To date, few data are available to quantify these emissions in relation to symbiotic nitrogen fixation. Long-term trials should be given high priority, so that all the effects can be measured and evaluated satisfactorily.
Further research is also required to improve the management of the nitrogen cycle, for instance, through optimisation of crop rotations, use of catch crops, intercropping or optimisation of fertilisation within the whole crop rotation.
When investigating the role of grain legumes in crop rotations, the effects of nitrogen which are specific to grain legumes, and non-nitrogen (or break crop) effects that also occur with non-legume crops should be distinguished. Often, these two types of effects are mixed up in discussion.
It is important that research takes into account the pedo-climatic effects in different countries and regions especially as there are close interactions between genetic background and environment. The challenge for genetic improvement of grain legumes by breeding lies in the creation of robust varieties with high and stable yields. There is potential for improvements in the composition of seed, changes in bioactive compounds and of protein degradability in the rumen.
Moreover, the workshop showed that plant and animal research should be linked more closely. Processes in the field can influence those in the barn, and vice versa: excreted nutrients should be returned to the field. It is a challenge for integrated systems research to optimise the nutrient cycles as far as possible.
Finally, for animal nutrition the workshop emphasised that the benefits of grain legumes could be increased by changing specific characteristics of the seed, either through plant breeding or through an appropriate treatment. The type of system used to evaluate the quality of feed was also highlighted as having a significant impact on the formulation. Optimising and unifying the different evaluation systems being used for grain legumes would help to get standardised values and clarify information for users.
This workshop was a first milestone. The analyses carried out should now be complemented and we hope that ongoing and future research projects will contribute to the knowledge base. Such multidisciplinary expertise is vital in order to exploit fully the potential of these low input crops for production and end use, avoid or reduce any negative effects and target more sustainable agriculture.
1Proceedings of the International Scientific Workshop ‘Grain legumes and the environment: how to assess benefits and impacts’, Zurich, 18–19 November 2004, (2006, Ed. AEP) cost €40 and can be ordered from the AEP office.
(a.schneider-aep@prolea.com)
