Do Coffee Agroforestry Systems Always Improve Soil Carbon Stocks Deeper in the Soil?—A Case Study from Turrialba, Costa Rica

Abstract

Shaded perennial agroforestry systems (AFS) are regarded as desirable land-use practices that improve soil carbon sequestration. However, most studies assume a positive correlation between above ground and below ground carbon without considering the effect of past and current land management, textural variations (silt and clay percentage), and such other site-specific factors that have a major influence on the extent of soil C sequestration. We assessed SOC stock at various depths (0–10, 10–30, 30–60, and 60–100 cm) in shaded perennial coffee (Coffea arabica L.) AFS in a 17-year-old experimental field at the Centro Agronómico Tropical de Investigación y Enseñanza, (9°53′44′′ N, 83°40′7′′ W; soil type: Ultisols and Inceptisols, Turrialba, Costa Rica. The treatments included coffee (Coffea arabica L.) grown conventionally (with chemical fertilizers) and organically (without chemical fertilizers) under two shade trees, Erythrina poeppigiana (Walp.) O.F. Cook., and Terminalia Amazonia J.F.Gmel., Sun Coffee (Coffea arabica L.) (Sole stand of coffee without shade), and Native Forest. Three replicated composite soil samples were collected from each system for each depth class, and SOC stocks in three soil aggregate fractions (2000–250 µm, 250–53 µm, and <53 µm) and in the whole soil determined. The total SOC stocks were highest under forest (146.6 Mg C ha−1) and lowest under sun coffee (92.5 Mg C ha−1). No significant differences were noted in SOC stock within coffee AFS and sun coffee across fraction sizes and depth classes. Organic management of coffee under heavily pruned E. poeppigiana, with pruned litter returned to soil, increased SOC stocks for 0–10 cm depth soil only. High input of organic materials including pruned litter did not improve SOC stocks in deeper soil, whereas variations in silt and clay percentages had a significant effect on SOC stocks. The study suggests that high amounts of aboveground biomass alone are not a good indicator of increased SOC storage in AFS, particularly for soils of sites with historical characteristics and management similar to this study.

Reservas de carbono en sistemas agroforestales con café (C. arabica L.) ante el cambio climático: caso México

“…Los resultados de COS en la línea base fueron superiores a los que obtuvieron Balaba Tumwebaze y Byakagaba (2016) en sistemas agroforestales de café (54,01 t ha -1 ) en un clima semicálido húmedo de Uganda. Pero fueron inferiores con los datos que reportaron Zaro et al (2020), quienes encontraron que los suelos de algunos sistemas cafetaleros de Brasil almacenaron alrededor de 195,60 t ha -1 de C. También fueron inferiores a los resultados generados por Chatterjee et al (2020), en sistemas cafetaleros bajo sombra de Costa Rica que almacenaron hasta 146,6 t ha -1 de C. El COS que se encontró en este estudio diferió con los resultados obtenidos por Chatterjee et al (2020), Balaba Tumwebaze y Byakagaba (2016) y Zaro et al (2020), debido a que las tipologías de los suelos fueron diferentes en cada región, además de que la influencia del clima y el manejo agronómico del sistema fueron determinantes en las reservas de COS (Jansson & Hofmockel, 2020).…”

“…El incremento del COS en los tres diseños agroforestales a los veinte años, se debió a la rotación del cultivo de café y a la rotación de la cohorte de plátano a los diez años en D2 y D3. El suelo, tanto en la línea base como en la simulación a cincuenta años, representó el mayor reservorio de C en los diseños agroforestales de café evaluados, tal como se registró en diversas investigaciones (Chatterjee et al, 2020;Ehrenbergerová et al, 2016;Solis et al, 2020).…”

Fine root contribution to the soil carbon stock of an agroforestry system in a Caatinga-Atlantic Forest transition zone

“…This indicated that the carbon accumulation in the 0-10 cm layer depended on more litter contribution than only the carbon originating from the fine root turnover, as in natural systems of Brazilian biomes (OZÓRIO et al, 2019). The influence of the FRC stock in the 10-20 cm layer was high due to a decreasing carbon incorporation rate from the surface to the deeper layer (CHATTERJEE et al, 2020). AFS are known to have complex re-lations between species which results in a heterogeneous environment, especially in the soil-plant transition.…”

“…In this work, fine roots were found in the surface layer and directly related to the higher concentration of organic matter and nutrients (WITSCHORECK; SCHUM-ACHER; CALDEIRA, 2003). Chatterjee et al (2020) also reported that the SOC stock in coffee AFS was increased only to a depth of 10 cm after 17 years of establishment due to shade-pruned Erytrina spp.…”

Agroforestry System as the Best Vegetation Management to Face Forest Degradation in Indonesia

“…An increase of 1 g kg −1 (0.1%) of soil organic carbon increases the available water capacity of the soil by 6% (vol/vol). Increased capacity of available water, relevant for the survival of the dry season during the week [62,63].…”