Long-Term Effect of Cover Crops on Species Abundance and Diversity of Weed Flora.

Alessia Restuccia,Aurelio Scavo,Cristina Abbate,Gaetano Pandino,Stefania Fontanazza,Sara Lombardo,Umberto Anastasi,Giovanni Mauromicale

doi:10.3390/plants9111506

Abstract

Cover crops are gaining in popularity as an eco-friendly tool for weed control in organic and low-input agricultural systems. A 5-year study was carried out in a Mediterranean environment (Sicily, south Italy) to (1) quantify cover crop biomass production and (2) evaluate the effects on weed soil seed bank, aboveground biomass, species richness, species composition and associations between communities. Cover crop treatments included subterranean clover (Trifolium subterraneum L.) and spontaneous flora, both with and without burying dead mulch into the soil, compared to a conventional management treatment. Weed biomass was significantly reduced by subterranean clover, contrariwise to spontaneous flora, with season-dependent results. Cover crop biomass, which ranged from 44 to more than 290 g DW m−2, was negatively correlated to weed biomass. Moreover, subterranean clover decreased the size of the soil seed bank and species richness. Based on relative frequency, a low similarity was found between the conventional management and cover crop treatments. In addition, no significant differences in species composition across treatments were observed, whereas principal component analysis highlighted some associations. The results suggest that subterranean clover cover cropping is a good option for weed management in Mediterranean agroecosystems.

Highlights

Specialized orchards of the arid or semiarid regions of the Mediterranean basin are often characterized by low levels of soil organic matter and severe weed infestations, which need a frequent use of chemical inputs for their management [1]
The real weed flora analysis showed that 38 weed species or genera were present in total throughout the study (Table 1), most of them were not high frequent enough to be analyzed for principal component analysis (PCA)
The present study aimed to evaluate the influence of 5 years of cover cropping, by subterranean

Summary

Introduction

Specialized orchards of the arid or semiarid regions of the Mediterranean basin are often characterized by low levels of soil organic matter and severe weed infestations, which need a frequent use of chemical inputs for their management [1] In these agroecosystems, weeds represent the most serious constraint to agricultural production, causing serious yield losses due to their highly competitive capacity and allelopathic activity [2,3]. Low biodiversity in agroecosystems is associated to the development of a selective weed flora more difficult to manage, and to a greater vulnerability to new invasive species [7] Both weed abundance and diversity are closely influenced by agricultural practices, mainly soil tillage systems, crop rotation and fertilization [8], with a central role played by environmental conditions [9,10]. Given the increasing interest in limiting the dependence on herbicides, weed control in croplands is addressing to find ecologically-based practices

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