Productivity, litter dynamics and soil fertility in agroforestry systems with coconut and cupuassu trees in eastern amazon

Abstract Agroforestry systems (AFS) are sustainable land use strategies that promote productivity and environmental conservation. The intercropping of coconut palm ( Cocos nucifera L.) and five progenies of cupuassu trees [ Theobroma grandiflorum (Willd. ex Spreng.) Schum.] was evaluated in terms of soil fertility, litter dynamics, and species productivity in Mojú, PA, Brazil. The experiment was implemented in randomized blocks with five treatments (AFS cultivated with cupuassu progenies 174, 186, 215, 286, and Tp) and four replicates. For some variables, these treatments were also compared to a native forest (FOR) and a pasture (PAS). Soil fertility variables at different depths, litterfall and stock, growth, and fruit production were evaluated using ANOVA (F-Test), mean comparison tests (Tukey test for variables involving the five experimental treatments only, and Fisher’s LSD tests, for variables involving the further areas besides the experimental treatments), and Principal Component Analysis (PCA) were applied to these data. Treatments 174, 286, and Tp showed the best fertility results, with pH up to 4.7, exchangeable Ca above 23 mmol c dm⁻ 3 , and BS above 50% in the 0–10 cm layer. FOR had lower pH (3.5) and higher Al saturation (Al sat = 79.5%). Litterfall showed greater accumulation in the dry season. Genotype 215 yielded higher fruits weight (102.5+7.0 kg ha −1 ), and pulp weights (40.5+3.2 kg ha −1 ), while 186 had more fruits per plant. Intercropping with cupuassu trees did not negatively affect the coconut trees and promoted maintenance of soil fertility, especially pH, SOM, P, exchangeable Ca and BS, compared to FOR and PAS. The results demonstrate that different cupuassu progenies offer different benefits, such as greater productivity or more positive impacts on soil fertility, which might be complementary to each other. Therefore, using progenies with these complementary attributes in the same planting with coconut trees can enhance the benefits of AFS.