Carbon Stocks, Litterfall and Pruning Residues in Monoculture and Agroforestry Cacao Production Systems

Abstract

SUMMARYAgroforestry systems (AFS) can serve to decrease ecosystem carbon (C) losses caused by deforestation and inadequate soil management. Because of their shade tolerance, cacao plants are suitable to be grown in AFS, since they can be combined with other kinds of trees and shrubs. The potential for C sequestration in cacao farming systems depends on various factors, such as management practices, stand structure and plantation age. We compared conventionally and organically managed cacao monoculture systems (MCS) and AFS in Sara Ana (Bolivia) with respect to C stocks in plant biomass and to amounts of litterfall and pruning residues. The total aboveground C stocks of the AFS (26 Mg C ha−1) considerably exceeded those of the MCS (~7 Mg C ha−1), although the biomass of cacao trees was greater in the MCS compared to the AFS. Due to higher tree density, annual litterfall in the AFS (2.2 Mg C ha−1 year−1) substantially exceeded that in the MCS (1.2 Mg C ha−1 year−1). The amounts of C in pruning residues (2.6 Mg C ha−1 year−1 in MCS to 4.3 Mg C ha−1 year−1 in AFS) was more than twice those in the litterfall. Annual nitrogen (N) inputs to the soil through pruning residues of cacao and N-fixing trees were up to 10 times higher than the N inputs through external fertiliser application. We conclude that appropriate management of cacao AFS, involving the pruning of leguminous trees, will lead to increases in biomass, litter quantity and quality as well as soil C and N stocks. Thus, we recommend stimulating the expansion of well-managed AFS to improve soil fertility and enhance C sequestration in soils.

Long-term dynamics of cocoa agroforestry systems established on lands previously occupied by savannah or forests

“…Such management schemes would lead to the renewal of mature and old systems whilst keeping good C storage abilities. However, the timespans -and levels -of C storage of Cameroonian cAFS remain highly significant in comparison to other agricultural systems or cocoa monocultures (Schroth et al, 2015;Schneidewind et al, 2018).…”

Oil palm agroforestry shows higher soil permanganate oxidizable carbon than monoculture plantations in Eastern Amazonia

“…Consistent with our hypothesis, the oil palm‐based AFS had a higher POx‐C content than did the oil palm monocultures. The AFS studied were composed of several species that contribute to C and soil nutrients via the following two mechanisms: (1) decomposition of the layer of plant material formed by litterfall (mainly T. cacao) and pruning (mainly T. cacao and G. sepium) (Dawoe et al, 2010; Fontes et al, 2014; Schneidewind et al, 2019) and (2) diverse root systems (in terms of morphology, architecture, association with microorganisms, and chemical composition) that incorporate C into the soil by root cycling and release of exudates in different amounts and depths (Hombegowda et al, 2016) and exploit soil resources better. Forest tree species generally have deeper root systems, resulting in the exploration of deeper layers of the soil, enabling them to access nutrients that are out of the reach of plants with rather superficial root systems as in agroforestry, such as T. cacao and E. oleracea (de Mendonça Góes et al, 2004; Martins & Augusto, 2012), which are then returned to the soil through litterfall (Das & Chaturvedi, 2008; Montagnini & Nair, 2004).…”

“…Forest tree species generally have deeper root systems, resulting in the exploration of deeper layers of the soil, enabling them to access nutrients that are out of the reach of plants with rather superficial root systems as in agroforestry, such as T. cacao and E. oleracea (de Mendonça Góes et al, 2004; Martins & Augusto, 2012), which are then returned to the soil through litterfall (Das & Chaturvedi, 2008; Montagnini & Nair, 2004). In general, AFS is more efficient than monocultures in incorporating C into the soil because of the higher production and quantity of litter (Schneidewind et al, 2019) and roots (Niether et al, 2019; Rajab et al, 2016) owing to the higher density and diversity of plants in AFS.…”

“…Consistent with our hypothesis, the oil palm-based AFS had a higher POx-C content than did the oil palm monocultures. The AFS studied were composed of several species that contribute to C and soil nutrients via the following two mechanisms: (1) decomposition of the layer of plant material formed by litterfall (mainly T. cacao) and pruning (mainly T. cacao and G. sepium) (Dawoe et al, 2010;Fontes et al, 2014;Schneidewind et al, 2019) and (2) diverse root systems (in terms of morphology, architecture, association with microorganisms, and chemical composition) that incorporate C into the soil by root cycling and release of exudates in different amounts and depths (Hombegowda et al, 2016) systems as in agroforestry, such as T. cacao and E. oleracea de Mendonça G oes et al, 2004;Martins & Augusto, 2012), which are then returned to the soil through litterfall (Das & Chaturvedi, 2008;Montagnini & Nair, 2004). In general, AFS is more efficient than monocultures in incorporating C into the soil because of the higher production and quantity of litter (Schneidewind et al, 2019) and roots (Niether et al, 2019;Rajab et al, 2016) owing to the higher density and diversity of plants in AFS.…”

Efecto del quitosano en la propagación vegetativa de cacao (Theobroma cacao L.) por esquejes

“…El valor en el mercado de dicha producción fue de $98.3 mil millones de dólares (Marketsandmarkets, 2017). La cual se concentra en 5.5 millones de pequeños productores (0.2 a 0.5 hectáreas), no es tecnif icada y se utilizan pocos insumos (Schneidewind et al, 2019). Se estima que en el futuro la producción mundial será insuf iciente para su demanda, debido a factores como: pérdida signif icativa por plagas y enfermedades, árboles envejecidos, rendimientos limitados, y efectos del cambio climático (Nieto-Figueroa et al, 2020).…”