1. Increasing plant diversity promotes ecosystem functions in rainfed rice based short rotations in Malagasy highlands
- Author
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Marie Sauvadet, Patrice Autfray, Jean Trap, Eric Blanchart, Aude Ripoche, Philippe Letourmy, Bodovololona Rabary, Thierry Becquer, Richard Randriamanantsoa, Agroécologie et Intensification Durables des cultures annuelles (UPR AIDA), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad), Centre National de Recherche Appliquée au Développement Rural (FOFIFA), Département Performances des systèmes de production et de transformation tropicaux (Cirad-PERSYST), Ecologie fonctionnelle et biogéochimie des sols et des agro-écosystèmes (UMR Eco&Sols), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut de Recherche pour le Développement (IRD)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Fonctionnement écologique et gestion durable des agrosystèmes bananiers et ananas (UR GECO), and STRADIV project (STRADIV project no. 1504-003) supported by Agropolis Foundation (France) and partly by CRP Rice Program supported by CGIAR
- Subjects
0106 biological sciences ,Agroecosystem ,[SDV.SA]Life Sciences [q-bio]/Agricultural sciences ,Rotation culturale ,agrobiodiversité ,F08 - Systèmes et modes de culture ,01 natural sciences ,7. Clean energy ,F07 - Façons culturales ,2. Zero hunger ,Ecology ,biology ,04 agricultural and veterinary sciences ,Legume ,Rendement des cultures ,Agroécosystème ,Diversification ,Cover crop ,Rotation ,Context (language use) ,Ecological intensification ,010603 evolutionary biology ,Crop ,Culture en mélange ,Riz pluvial ,Ecosystem services ,Monocropping ,15. Life on land ,Crop rotation ,Sorghum ,biology.organism_classification ,services écosystémiques ,Agronomy ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,Système de culture ,Animal Science and Zoology ,Soil fertility ,[SDE.BE]Environmental Sciences/Biodiversity and Ecology ,Weed ,Agronomy and Crop Science ,Agroecology - Abstract
International audience; Plant diversification is one of the main ways to ecologically intensify agroecosystems to improve their sustainability and resilience. Rotations and/or a mixture of crops can mitigate pest and weed infestation, reduce diseases, and improve soil fertility and crop productivity. However, rainfed rice yields in the Malagasy highlands remain low despite the frequent use of cropping systems including crop rotations and mixtures. In this study, we compared three rainfed rice based short rotations with rainfed rice monocropping to quantify the benefits of plant diversification on different ecosystem functions such as weed and nematode control, soil fertility, soil macrofauna abundance and diversity, and rice yield over four cropping seasons. The three rotations were based on rice in rotation with one legume, groundnut (RG), a cereal-legume mixture, sorghum and cowpea (RSC), or a mixture of legumes, velvet bean and crotalaria (RVC). Rice growth, N content and yield, soil N content, weed biomass, nematofauna and macrofauna were assessed and a profitability analysis was performed at rotation scale. The legume mixture had a significant and positive effect on rice growth, N content and yield, soil N content, and weed and nematode control due to high biomass production in the cropping cycle including legume mixture, by limiting weed growth and leaving a large quantity of N-rich residues to enrich the soil for the following rice crop. The nematicide properties of the legume mixture may reduce the infestation of plant-feeding nematodes. The RG and RSC rotations produced intermediate results. While rice yields were higher in these rotations than when rainfed rice was grown alone, weed biomass remained high due to minimal competition with weeds during the crop rotation cycle especially with groundnut. For RSC, nematode control was limited as both sorghum and cowpea are host plants for nematodes. Despite a year with no crop income with the RVC rotation, profitability was higher mainly due to the increased rice yield and reduced field management costs. The choice of species is thus crucial to optimise ecosystem functions adapted to farmers’ context and objectives.
- Published
- 2021