Eco-functional intensification by cereal-grain legume intercropping in organic farming systems for increased yields, reduced weeds and improved grain protein concentration

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Organic farming is based on to rely on a higher cropping systems diversity than its conventional counterpart and is regarded as one prototype to enhance the sustainability of agriculture and cereal-rich cropping systems. Nevertheless, organic arable crop rotations in temperate regions consist mainly of sole crops (SC; pure stands), with diverse pastures in farming systems with livestock being an exception (Hauggaard-Nielsen et al. 2001b).
In organic farming, nitrogen (N) availability can be limiting especially in the absence of livestock (David et al. 2005ab) and causes cereal yield depressions and lower protein contents. For these reasons, integrating legumes with symbiotic fixation of atmospheric N2 is essential for balancing nitrogen exports from the system. New agronomic solutions should be developed addressing multifunctionality including: i) higher yields; ii) improved quality; iii) provision of ecosystems services and iv) the adaptation of production systems to climate change (IAASTD 2009). Intercropping (IC) cereals and legumes, i.e. simultaneously growing two (or more) species in the same field for a significant period but without necessarily sowing or harvesting them at the same time (Willey 1979; Vandermeer et al. 1998; Malézieux et al. 2008) is a practice for eco-functional intensification, which is considered a mean to enhance yields in organic farming (Niggli et al. 2008). However, due to the intensification of agriculture during the last 50 years (Crews and Peoples 2004) annual intercropping is now rare in European countries (except for animal feeds) and elsewhere in intensive farming systems (Anil et al. 1998; Malézieux et al. 2008). Nevertheless, because of the numerous ecosystems services in introducing cereal-legume intercropping (Hauggaard-Nielsen and Jensen 2005) there seems to be a renewed interest in cereal/legume intercrops in Europe, notably in organic farming (Anil et al. 1998; Malézieux et al. 2008) as a mean of eco-functional intensification.
Intercropping has been shown to increase and stabilize yields (Hauggaard-Nielsen et al. 2009b; Lithourgidis et al. 2006) and to increase cereal grain protein content and baking quality compared to sole crops (Gooding et al. 2007), particularly in low-N input systems and organic farming where N can be a limiting resource (Corre-Hellou et al. 2006; Bedoussac and Justes 2010ab; Naudin et al. 2010). Intercropping has also been shown to: i) improve soil conservation (Anil et al. 1998); ii) favour weed control (Vasilakoglou et al. 2005; Banik et al. 2006; Corre-Hellou et al. 2011); iii) reduce pests and diseases (Trenbath 1993; Altieri 1999) and iv) provide better lodging resistance (Anil et al. 1998). In contrast, grain legumes, such as peas (Pisum sativum L.) grown as sole crops are known to be weak competitors towards weeds (Wall et al. 1991; Townley-Smith and Wright 1994; Mcdonald 2003), and weed infestations have been shown to severely limit the N nutrition and grain yield of organically grown grain legumes (Hauggaard-Nielsen et al. 2001b; Corre-Hellou and Crozat 2005). Moreover grain legumes sole crops are sensitive to lodging and affected by numerous pests and diseases, which can cause serious yield losses in organic farming where pesticides use is forbidden. Thus, from these perspectives intercropping can be a way to successfully produce organic grain legumes (Hauggaard-Nielsen et al. 2007).
The main objective of the study is to analyze and describe the potential advantages of cereal-grain legume intercrops for gr ain yield, grain protein content and weed control in organic cropping systems. This chapter integrates a comprehensive amount of original data from field experiments conducted since 2001 in France (south and west, with contrasting soil and climatic conditions) and Denmark, in experimental and farm contexts, on spring and winter cereal-grain legume intercrops (Table 1) to try and generalize the findings for more common guidelines.

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• Intercropping, an application of ecological principles to improve nitrogen use efficiency in organic farming systems. (deposited 27 Jun 2011 15:06)
  • Eco-functional intensification by cereal-grain legume intercropping in organic farming systems for increased yields, reduced weeds and improved grain protein concentration. (deposited 13 Jun 2012 06:36) [Currently Displayed]