The Application of Coffee Pulp Biochar Improves the Physical, Chemical, and Biological Characteristics of Soil for Coffee Cultivation

A field experiment was conducted for 2 years (2019 and 2020) to determine the response to the application of Biochar (BC) obtained from the coffee pulp in combination with chemical fertilization (CF) in coffee trees. The established treatments were the edaphic application of different doses of BC (0, 4, 8, and 16 t ha −1 ) and levels of CF (0, 33, 66, and 100% of the nutritional requirements) on the physical (bulk density (ρ a ), stable aggregates), chemical (nutrient availability), and biological (respiration) properties of soil from a coffee crop. Regarding the physical properties, it was mainly observed that BC doses of 8 or 16 t ha −1 reduced ρ a (0.82 and 0.83 g cm −3 , respectively) and increased the aggregation status (96.5% and 96.84%, respectively) in comparison to 0 t ha −1 in 2020. The chemical properties showed that the application of 16 t ha −1 BC decreased about 60% of the exchangeable acidity (EA) compared to the control (0 t ha −1 ) whereas the pH (4.96 and 4.92) and organic carbon (OC) (4.41 and 4.59) were higher than in the control soil (EA: 0.58 and 0.54 meq/100 g; pH: 4.63 and 4.55; OC: 4.17 and 4.32% in 2019 and 2020, respectively). Soil respiration (biological property) strongly increased (around 50–60%) with the combination of 66% CF and BC doses between 8 and 16 t ha −1 in both years. Doses between 8 and 16 t ha −1 BC of the coffee pulp can improve the quality of soils for coffee cultivation and provide an alternative and more sustainable amendment that may help reduce chemical fertilization.