May the Inclusion of a Legume Crop Change Weed Composition in Cereal Fields? Example of Sainfoin in Aragon (Spain)

Alicia Cirujeda,Joaquín Aibar,Sonia Murillo,Ana Isabel Marí,Xavier Oriol Solé-Senan,Gabriel Pardo

doi:10.3390/agronomy9030134

Abstract

Onobrychis viciifolia (Scop.) (sainfoin) is promoted in the Spanish Aragón region through the Agro-Environmental Schemes (AES) since 2007 with the aim of enhancing biodiversity. Also, in other countries, the interest in this legume crop is growing due to its rusticity and beneficial effects on the soil and livestock. However, the effect of the crop on weed flora in the subsequent cereal crops has hardly been investigated yet. With this aim, weed flora has been characterised in 2011–2014 in sainfoin fields in the second and third year of establishment (S2 and S3), in cereal monocrop (CM), in cereal after sainfoin (CS) and in organic cereal fields (OC). Additionally, the soil seedbank was determined in two years in CM and S3 fields. Weed species richness of emerged flora and of the soil seedbank was highest for sainfoin and lowest for CM, being intermediate for OC and CS regardless of the sampling year. The most feared weed species in winter cereal did not increase by growing sainfoin or in CS compared to CM. Curiously, summer annuals dominated in the soil seedbank. Sainfoin fields cause thus a shift in the weed flora, which does not seem to damage subsequent cereal crops provided fields are mouldboard ploughed after sainfoin.

Highlights

Since the new Common Agrarian Policy enacted in 2015, so-called “greening” encourages farmers to include different crops in their rotation
The objectives of this work are (1) to describe the weed flora in sainfoin fields in the second and third years (S2 and S3) in cereal monocrop fields (CM), in cereal grown after sainfoin (CS) and in organic cereal fields (OC) and (2) to evaluate the weed soil seedbank in S3 compared to CM and, to find out if growing sainfoin during three years increases the abundance of weeds in following cereal crops
The effect of crop was significant for the Shannon Diversity Index and species richness, whereas the effect of year was significant for species richness only (Table 1)

Summary

Introduction

Since the new Common Agrarian Policy enacted in 2015, so-called “greening” encourages farmers to include different crops in their rotation. In Spanish dryland areas, this measure has led to an increase in sowing legume crops in low-land areas, mainly vetch and lucerne. Between 2007 and 2014, one of the Agri-Environmental Schemes (AES) financed by the Aragón Government has been promoting sainfoin (Onobrychis viciifolia Scop.) with the objective of favouring steppe fauna, especially enhancing the nesting and reproduction of steppe birds. In the new Rural Development Plan (2015–2020) this measure has been included once more aiming to combine agriculture and environmental protection. Sainfoin is a forb belonging to the Fabaceae family and is grown as perennial forage on calcareous soils. The main climatic limitations of sainfoin are high temperatures and soil temperatures exceeding

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