Effects of Applying Arbuscular Mycorrhizal Fungi to Nitrogen Cycle Microorganisms in Soils with Coffee Plantations

Abstract

Abstract: Mycorrhizae are associations between plants and beneficial fungi. They are the most active components of the plant’s nutrient absorption organs. On the other hand, soil microorganisms are fundamental for their functioning and dynamics as a living system. This research aimed to evaluate the effects of applying arbuscular mycorrhizal fungi (AMF) to the abundance of functional groups associated with the nitrogen cycle of soils with coffee plantations in Sasaima, Cundinamarca, Colombia. The soil samples were collected from four study plots during months 0, 2, and 8 and handled as follows: Plot 1. Application of liquid AMF (75-80 spores/gram of dry powder); Plot 2. Application of AMF in solid formulation (300 spores/gram); Plot 3. Application of native AMF, extracted from the soil under study (25 spores/gram); and Plot 4. Control, no application of AMF . The abundance of soil microorganisms associated with the nitrogen cycle was estimated using the most probable number technique to quantify ammonifying, proteolytic, ammonium-oxidizing, nitrite-oxidizing, and denitrifying microorganisms. The standard physicochemical parameters of the soil were measured. Afterward, univariate and multivariate analyses of the data were performed. The results showed a positive correlation between the application of AMF, organic carbon, and phosphorus, higher in the plots with native AMF. However, the abundance of functional groups of the nitrogen cycle did not show significant differences among the treatments; still, the principal components analysis showed a correlation between the plots with liquid and solid AMF, ammonifying microorganisms, and ammonium-oxidizing bacteria.