Introduction: In natural systems and agroecosystems, the study of soil carbon and nitrogen as a function of the type and magnitude of their plant cover is important because the concentration and content of these elements are related to soil fertility and quality and environmental impact.
Objectives: To determine the carbon and nitrogen in the soil as a function of the type and magnitude of the plant cover of tropical montane cloud forest (TMCF) systems, full sun coffee monoculture (FSCM), coffee agroforestry system as a traditional polyculture (CASTP) and coffee agroforestry system as a commercial polyculture (CASCP).
Materials and methods: Plant covers were characterized and quantified. Soil samples were taken at depths of 0 to 10, 10 to 20 and 20 to 30 cm to determine the concentrations and contents of soil organic carbon (SOC) and nitrogen in its total (Nt), organic (Norg), nitrate (NO3-), ammonium (NH4+) and mineral (Nmin) forms.
Results and discussion: The order of magnitude of plant cover was TMCF>CASTP>CASCP>FSCM. The same order was found in SOC (TMCF: 229.33 Mg·ha-1, CASTP: 211.03 Mg·ha-1, CASCP: 90.95 Mg·ha-1 and FSCM: 92.56 Mg·ha-1), Nt (TMCF: 16.10 Mg·ha-1, CASTP:14.21 Mg·ha-1, CASCP: 7.89 Mg·ha-1 and FSCM: 6.50 Mg·ha-1) and Norg (TMCF: 16.02 Mg·ha-1, CASTP:14.16 Mg·ha-1, CASCP: 7.82 Mg·ha-1 and FSCM: 6.44 Mg·ha-1) stocks. The C:N ratio was similar in the systems.
Conclusions: The TMCF and CASTP had the largest organic carbon and Nt stocks in the soil. Agroforestry systems with coffee were better than coffee monoculture.