Litter layer and earthworms as an indicator of coffee production in the coffee and pine based agroforestry system

Critical support for successful coffee-based agroforestry production is the amount of litter input and the activity of macro-organisms. The purpose of this study was to analyze the relationship between the amount of litter on the soil surface, the population of earthworms, and the growth and production of coffee. The research was conducted between June 2019 and March 2020 at the Universitas Brawijaya Forest, East Java, Indonesia. For the coffee plants, a proportional random sampling method was used to capture the range of plant sizes within the study location. The range of diameters at breast height (DBH) recorded were divided into ten decils and four replicates within each decil. For each plant, DBH was transformed into tree biomass and fresh coffee bean weight was also measured. Litter weight and depth were measured using a 50 x 50 cm quadrat frame. A sampling of earthworms used the TSBF monolith method. There was a positive relationship between litter thickness, litter weight, the number of earthworms, and earthworm biomass against the dry weight coffee bean, while the four variables have no significant relationship with coffee tree biomass. We concluded that litter layer and earthworm biomass can be used as a simple indicator of coffee production.