Contribution of nitrogen from litter and soil mineralization to shade and sun coffee (Coffea arabica L.) agroecosystems
Date of Original Version
Coffee (Coffea arabica L.) production is important for its economic, ecological and social values in tropical areas. Whether coffee is grown under shade (SHD) or full sunlight (SUN), may have a direct impact on soil nitrogen (N) cycling, which can affect yield and agroecosystem sustainability. We studied N cycling in coffee farms in three municipalities in Puerto Rico and evaluated three ecosystem types in each: SUN coffee, SHD coffee and secondary forest (FOR). Aboveground litter dry matter and litter N inputs were quantified. Litter dry matter inputs (t ha-1year-1) were higher in SHD (2.15) and FOR (1.83), and were significantly greater than SUN (1.40). Litter N inputs (kg N ha-1year-1) were significantly lower in SUN (31) than in SHD (52) and FOR (43). Cycling of N was evaluated in detail in the municipality of Las Marias in SHD and SUN coffee. Litter N inputs (kg N ha-1year-1) to soil were significantly different between FOR (41) and SHD (56). The standing stock of N in aboveground biomass SHD was ∼3 times that in SUN, and total N input was twice that in SUN. However, soil N standing stocks were similar in SHD and SUN, indicating faster litter N turnover in SUN than in SHD ecosystems. By contrast, net soil N mineralization rates (kg N ha-1year-1) were ∼2 times higher in SHD (96) than in SUN (49), indicating that soil N turnover is greater in SHD than SUN. Our results suggest that litter N is mineralized at a slower rate in SHD than in SUN, whereas soil N is mineralized at a slower rate in SUN than in SHD. Higher inputs of N to soil, and soil N turnover in SHD may result in improved coffee production and associated forest biomass N uptake. Higher soil N mineralization rates in SHD coffee suggest improved ecosystem sustainability than in SUN coffee, presumably due to higher microbial activity, greater microbial diversity and substrate availability.
Publication Title, e.g., Journal
López-Rodríguez, Glenny, David Sotomayor-Ramírez, José A. Amador, and Eduardo C. Schröder. "Contribution of nitrogen from litter and soil mineralization to shade and sun coffee (Coffea arabica L.) agroecosystems." Tropical Ecology 56, 2 (2015). https://digitalcommons.uri.edu/nrs_facpubs/250