Agriculture, Ecosystems and Environment 324 (2022) 107705 Available online 23 October 2021 0167-8809/© 2021 Elsevier B.V. All rights reserved. Leaf litter species affects decomposition rate and nutrient release in a cocoa plantation Shahla Hosseini Bai a, * , Marta Gallart a , Kanika Singh b , Godfrey Hannet c , Birte Komolong d , David Yinil e , Damien J. Field b , Bushra Muqaddas a , Helen M. Wallace a a Centre for Planetary Health and Food Security, School of Environment and Science, Griffth University, Nathan Campus, QLD 4111, Australia b Sydney Institute of Agriculture and School of Life and Environmental Sciences, The University of Sydney, Eveleigh, NSW 2015, Australia c National Agricultural Research Institute, Islands Regional Centre – Keravat, Post Offce Box 204, Kokopo, East New Britain Province, Papua New Guinea d National Agricultural Research Institute, Head Offce, P.O. Box 4415, Lae, Morobe Province, Papua New Guinea e Cocoa Board of Papua New Guinea, Head Offce, P.O. BOx 532, Rabaul, Papua New Guinea A R T I C L E INFO Keywords: Cocoa Shade-tree species Litter decomposition Nutrient release Soil nutrients ABSTRACT Mineral nutrient fuxes derived from litterfall are key components of nutrient biogeochemical cycles in both natural and agroforesty systems. Cocoa production systems are generally nutrient depleted and may beneft from on external nutrient application to maintain primary productivity. However, in developing countries the main source of nutrients is often nutrient recycling through decomposing leaf litter, and in this regard shade-tree species play an important role in cocoa agroforestry. This study aimed to investigate the nutrient inputs of litter from two shade-tree species (Canarium indium and Gliricidia sepium) and cocoa trees (Theobroma cacao) after 15 months of decomposition in a cocoa plantation. Litter from G. sepium lost more mass (59%) than T. cacao (37%) and C. indium (10%), and showed a higher average concentration of total nitrogen (TN), boron (B), iron (Fe) and phosphorus (P) after 15 months of feld incubation than that of C. indium. It also showed a low C:N ratio and N release, which suggest N mineralisation. All litter species showed high C:P ratio and negative P release, which suggests P immobilisation. Litter from G. sepium and T. cacao showed a rapid K release after 1 month of decomposition. The differing mass loss rates and litter nutrient concentrations of the three species could beneft T. cacao by providing asynchronous nutrient inputs and improve long-term sustainability of mixed-species plantations. 1. Introduction Plant litter decomposition is a fundamental process in nutrient dy- namics in all terrestrial ecosystems and is driven by microbial activity. Rates of litter decomposition determine how quickly nutrients released from plant litter are taken up by plants, soil microorganisms, and soil fauna (Coleman et al., 2020; Porre et al., 2020). The main factors infuencing leaf litter decomposition rates have been identifed as plant species and genotypes, climate and local soil properties, however, we still lack detailed knowledge that integrates litter decay rates in biogeochemical cycles within and among ecosystems (Freschet et al., 2013). This gap compromises our ability to predict the impact of lit- terfall in the functioning of natural and managed ecosystems (Vigulu et al., 2019; Porre et al., 2020). The establishment of sustainable agroecosystems that synchronise nutrient release from organic residues and meet plant nutrient and water requirement is under debate (Kho, 2000). Nitrogen (N), phosphorus (P) and potassium (K) are considered essential nutrients for plant growth and development (Kho, 2000; Isaac et al., 2007a, 2007b). Plants also require small concentrations of boron (B), calcium (Ca), iron (Fe), K, magnesium (Mg), manganese (Mn) and zinc (Zn) to maintain optimal plant growth and development (Vanhove et al., 2016; Zaia et al., 2012). As many terrestrial ecosystems are often limited in nutrient availability, intensive agroforestry systems conventionally apply external nutrient sources including mineral fertilisation, organic amendments, and compost to replenish soil nutrients (Nguyen et al., 2017; Vigulu et al., 2019). Cocoa (Theobroma cacao) is one of major cash crops (Bai et al., 2017), which is often produced in agroforest plantations that have high nutrient demand (Bai et al., 2017; Hosseini-Bai et al., 2019; Singh et al., 2019a). On average, a metric tonne of harvested T. cacao pods exports * Corresponding author. E-mail address: s.hosseini-bai@griffth.edu.au (S.H. Bai). Contents lists available at ScienceDirect Agriculture, Ecosystems and Environment journal homepage: www.elsevier.com/locate/agee https://doi.org/10.1016/j.agee.2021.107705 Received 23 May 2021; Received in revised form 30 September 2021; Accepted 4 October 2021