Agroforestry systems are an alternative option for sustainable production management. These systems contain trees that absorb nutrients from deeper layers of the soil and leaf litter that help improve the soil quality of the rough terrain in high altitude areas, which are areas extremely susceptible to environmental degradation. The aim of this study was to characterize the stock and nutrients in litter, soil activity and the population of microorganisms in coffee (Coffea arabica L.) plantations under high altitude agroforestry systems in the semi-arid region of the state of Pernambuco, Brazil. Samples were collected from the surface litter together with soil samples taken at two depths (0-10 and 10-20 cm) from areas each subject to one of the following four treatments: agroforestry system (AS), native forest (NF), biodynamic system (BS) and coffee control (CT).The coffee plantation had been abandoned for nearly 15 years and, although there had been no management or harvesting, still contained productive coffee plants. The accumulation of litter and mean nutrient content of the litter, the soil nutrient content, microbial biomass carbon, total carbon, total nitrogen, C/N ratio, basal respiration, microbial quotient, metabolic quotient and microbial populations (total bacteria, fluorescent bacteria group, total fungi and Trichoderma spp.) were all analyzed. The systems thatwere exposed to human intervention (A and BS) differed in their chemical attributes and contained higher levels of nutrients when compared to NF and CT. BS for coffee production at high altitude can be used as a sustainable alternative in the high altitude zones of the semi-arid region in Brazil, which is an area that is highly susceptible to environmental degradation

Biochar is a material produced by the pyrolysis of agro-industrial waste, which has become one of the most promising management tools to improve soil quality. The aim was to determine the effects of incorporating biochar from different coffee wastes in sandy soil, cropped with maize, on soil chemical and microbial attributes. The experiment followed a factorial design 2 × 3 + 1 with two types of biochar, including coffee ground (CG) or coffee husk (CH) in 3 doses (4, 8, and 16 t·ha-1) and a control fertilized solely with bovine manure (3 t·ha-1). The variables analyzed were soil organic carbon, chemical attributes, microbial biomass (C, N and P), soil basal respiration and microbial gene abundance (16S rRNA, 18S rRNA and nifH gene). Most chemical attributes were strongly increased by CH application, while CG at 8 t·ha-1 increased the soil C:N ratio (3.5 times), P (2.1 times) and K+ (7.9 times) and at 4 t·ha-1 increased the C content, microbial biomass C and N (3, 2.1 and 1.6 times, respectively). The application of CG biochar at 16 t·ha-1 showed trend to increase the abundance of bacteria, fungi and diazotrophic genes (11, 10 and 2%, respectively). Contribution of both coffee biochar types, but mainly CH, was more effective than the soil that received organic manure alone. Biochar from coffee wastes is a promising tool to improve sandy soil quality.

Biochar has been used to reuse the agro-industrial wastes and improve soil quality. Several studies have been carried out to show the impact of biochar on physical and chemical soil attributes. However, there are still gaps regarding the effects on as microbial biomass and enzymatic activities that are important to determine sensitive indicators to evaluate changes in management practices. The objective of this study was to assess the effect of two biochars on the chemical, microbial biomass carbon, and the enzymatic activities in an Entisol cultivated with bean. We evaluate two types of coffee biochar: ground and husks, four doses (4, 8, 12, and 16 Mg ha-1) and control. All treatments received organic fertilization with cow manure. Husks biochar increase the soil pH, Ca, and K, also contributing to the reduction of toxic aluminum contents and raising the concentrations of P labile. The treatments that received ground biochar showed higher soil organic carbon, microbial biomass, β-glucosidase, and fluorescein diacetate. Biochar produced from coffee residues increased sandy soil quality. We showed the first report on the beneficial impact of coffee biochar on enzymatic and microbiological quality of sandy soil cultivated with the bean.

Plant growth-promoting bacteria (PGPB) are an effective tool for improving nutrients in agricultural systems; however, their efficacy depends on successful colonization in soils. To address this challenge, biochar has been identified as an effective material for enhancing soil ecosystem services and can serve as a protective for PGPB. However, the impact of biochar and PGPB on soil health indicators and plant growth remains poorly understood. This study aimed to evaluate the effects of biochar and PGPB on soil chemical and biological properties in cowpea. We used biochar from bean husk (BHB) and grape fermentation residue (GFB) and Bradyrhizobium elkanii USDA 76 (BRA), Burkholderia cepacia ATCC 25416 (PRB), or Rhizobium altiplani BR10423 (RHI). BHB and PRB stimulated cowpea growth, while GFB and PRB promoted soil phosphatase activity. Overall, different combinations of biochar and PGPR increased soil pH, phosphorus, potassium, organic carbon content, and urease activity, but did not affect microbial biomass carbon and β-glucosidase activities. The biochars inoculated with the BRA showed the highest productivity. For example, plants subjected to the BRA + GFB treatment exhibited a 3.85-fold increase in productivity compared to the additional treatment that involved the use of commercial peat. The study demonstrated a positive effect of biochar and PGPB on soil enzymatic activity, nutrient content, and cowpea growth suggesting a sustainable alternative to chemical fertilizers, especially in poor soils. These findings highlight the potential of biochar as an environmentally sustainable carrier of PGPB while addressing the issue of agricultural waste reuse.