Soil Carbon Dynamics under Pastures in Andean Socio-Ecosystems of Colombia

María-Cristina Ordoñez,Apolinar Figueroa,Leopoldo Galicia,Juan Fernando Casanova Olaya

doi:10.3390/agronomy10040507

Abstract

Models can help to explain the main interactions, magnitudes, and velocity by which biological processes accumulate soil organic carbon (SOC) in pastures. An explanatory model using Insight Maker software was constructed for each soil under natural and cultivated pastures, using theoretical carbon models and data which were collected monthly in andisol sites. The model was calibrated and validated by comparing the modeled data to the field data until the smallest prediction error was reached. The indicators used were the mean absolute error (MAE), root-mean-square error (RMSE), mean absolute percentage error (MAPE) and the coefficient of determination (R2). In natural pasture soil, the diversification of organic inputs consistently promoted the growth of microbial biomass and metabolic efficiency. In contrast, intensive management of cultivated pastures, involving the removal of plant cover, plowing and low input of organic matter, stressed the microbial community and increased the potential carbon loss through secondary mineralization and surface runoff. The application of modeling indicated that it is necessary to improve agronomic practices in cultivated pastures, to maintain soil cover and to increase the application of organic fertilizer by 1.5 times, in order to reduce stress on the microbial biomass, accumulate SOC, minimize organic matter mineralization and reduce C losses due to surface runoff. Therefore, improving agricultural management based on the understanding of soil processes will allow increasing the potential for SOC storage, while improving pasture sustainability.

Highlights

Pasture makes up the largest percentage of terrestrial ecosystems [1]
This paper focuses on modeling main interactions, magnitudes, and velocity by which the biological processes accumulate soil carbon under two pasture management schemes in Andean socio-ecosystems in Colombia
The formation of metabolites and CO2 derived from the processes is increased; they have the necessary amounts of carbon to guarantee the formation of soil aggregates and the carbon availability for the formation of cellular tissue

Summary

Introduction

Pasture makes up the largest percentage of terrestrial ecosystems [1]. The largest reservoir of organic carbon in pastures is the soil organic matter, which contains about 90% of the total system organic C [2]; the primary mechanisms that regulate carbon content in pasture ecosystems include inputs and losses of organic matter [3,4]. Fisher et al [5] estimated that the input of organic matter into managed pasture soils ranges from 33.5 to 40.5 Mg ha−1 year−1. In the literature on Andean pastures, the relationships between management and soil organic carbon (SOC) storage, based on the magnitude, distribution and transfer of carbon in the soil ecosystem, are unknown.

Methods

Results

Discussion

Conclusion