Inoculation with a soil fungus accelerates decomposition of avocado cv. Hass leaf litter in three plantations in Colombia

Abstract

The objective of this study was to evaluate the effect of a fungal inoculation on the litter decomposition in three plantations of avocado (Persea americana) cv. Hass in Colombia at different altitudes (Támesis 1340 m, Jericó 1900 m, and Entrerríos 2420 m). These processes are key in the proper functioning of soil biogeochemical cycles. The litter was either uninoculated or inoculated with the fungus Mortierella sp., then transferred into litter bags and finally deposited in the field sites where remained for 430 days. Residual dry matter (RDM) and nutrient content was monitored overtime. Five regression models of litter decomposition were employed: single, double, and triple exponential models and two continuous models. Although, all models properly fitted the data variation, the double exponential was the most effective based on regression parameters (mean square error and Akaike index). In all three sites the rate of decomposition was higher when the litter was inoculated with the fungus. Thus, the RDM was significantly lower when the litter was inoculated with Mortierella sp. At day 430, the uninoculated RDM in Tamesis, Jerico, and Entrerrios was 0.48, 0.47, and 0.50, respectively; while the inoculated RDM was 0.47, 0.44, and 0.46, respectively. The rate of decomposition followed the decreasing sequence: Jericó > Támesis > Entrerríos. The nutrient release pattern was: K > Ca > Mg > N > P > Cu > Mn > Zn > Fe. While K was rapidly released, Ca, Mg, and N were slowly released; P, Cu, Mn, Zn, and Fe were immobilized during the decomposition process. However, fungal inoculation on the litter significantly reduced the magnitude of nutrient accumulation for P, Mg, S, Mn, and Zn. This effect was variable overtime and among sites. Litter N and P contents and the N:P ratio were good indicators of the decaying process.

Effect of a Wood-Based Carrier of Trichoderma atroviride SC1 on the Microorganisms of the Soil

“…These fungi are considered good degraders of toxic pollutants, such as pesticides and heavy metals [ 91 , 93 , 94 ], and they have potential for biocontrol [ 95 , 96 , 97 ]. They are also important plant growth promoters and can enhance soil conditions under salt stress [ 98 , 99 ], but most importantly, they can degrade cellulose, hemicellulose, and organic matter in periods that range from 30 to 430 days, depending on the substrate and the soil conditions [ 100 , 101 ]. Tamayo-Vélez et al [ 100 ] reported an optimal degradation rate of organic matter by Mortierella 90 days after inoculation.…”

“…They are also important plant growth promoters and can enhance soil conditions under salt stress [ 98 , 99 ], but most importantly, they can degrade cellulose, hemicellulose, and organic matter in periods that range from 30 to 430 days, depending on the substrate and the soil conditions [ 100 , 101 ]. Tamayo-Vélez et al [ 100 ] reported an optimal degradation rate of organic matter by Mortierella 90 days after inoculation. These results can be compared to what we have observed, as 90 days were sufficient to rank Mortierella spp.…”