Farm Table says:
A Review of the Literature:
World population is projected to reach over nine billion by the year 2050, and ensuring food security while mitigating environmental impacts represents a major agricultural challenge. Thus, higher productivity must be reached through sustainable production by taking into account climate change, resources rarefaction like phosphorus and water, and losses of fertile lands.
Enhancing crop diversity is increasingly recognized as a crucial lever for sustainable agro-ecological development. Growing legumes, a major biological nitrogen source, is also a powerful option to reduce synthetic nitrogen fertilizers use and associated fossil energy consumption. Organic farming, which does not allow the use of chemical, is also regarded as one prototype to enhance the sustainability of modern agriculture while decreasing environmental impacts.
The main objective of this article is to describe and analyze the potential advantages of cereal-grain legume intercrops with species sown and harvested together in organic cropping systems focusing on grain yield, grain protein concentration, nitrogen use, weed control and economic gross margin.
The review is based on a literature analysis reinforced with the integration of an original dataset of 58 field experiments conducted since 2001 in contrasted pedo-climatic European conditions in order to generalize the findings and draw up common guidelines.
The major points are that intercropping lead to:
- higher and more stable grain yield than the mean sole crops (0.33 versus 0.27 kg m−2 )
- higher cereal protein concentration than in sole crop (11.1 versus 9.8 %)
- higher and more stable gross margin than the mean sole crops (702 versus 577€ha−1 )
- improved use of abiotic resources according to species complementarities for light interception and use of both soil mineral nitrogen and atmospheric N2.
Intercropping is particularly suited for low-nitrogen availability systems but further mechanistic understanding is required to propose generic crop management procedures. Also, development of this practice must be achieved with the collaboration of value chain actors such as breeders to select cultivars suited to intercropping.
As a final remark, it is important to emphasize that the development of intercrops cannot take place without the assent and collaboration of all the actors in the value chain because the low degree of integration of the supply chain can be viewed as a lock-in mechanism.
- the farmers who need technical support since the new generation of farmers may not possess the know-how to grow arable crops as intercrops and organically
- the companies collecting and storing seeds which will have to adapt their collecting, sorting and storage equipment to satisfy the processors’ quality demands
- the industrials to adapt food processing
- the breeders expected to select varieties suited to intercropping
- the technical institutions which must acquire and transfer operational knowledge
- the researchers to produce cognitive know-how on the multiple mechanisms in play
- the national and European authorities to consider relevant policy and subsidies to help to reintroduce these cropping strategies.