Predicting soil CO2 emissions and sinks due to soil management factors of Brachiaria decumbens pastures using Tier 2 IPCC Methodology

Abstract

Soil carbon sequestration refers to the process of transferring carbon dioxide (CO2) from the atmosphere into the soil. The objective of this research was to do a simulation of how soil management factors in pastures can contribute to mitigate climate change by reducing soil CO2-eq emissions due to increases of soil organic carbon.  In livestock systems of Cumaral (Meta), Colombia, IPCC Tier 2 methodology was used to compare changes in soils C stocks under (a) two pasture types: Brachiaria decumbens grass pastures (B1) and Brachiaria decumbens grass pastures associated with Pueraria phaseloides legume (B2); (b) four increasing doses of CaCO3: 0, 1.1, 2.2, 3.3 tons ha-1; (c) three sources of N, P, K fertilizers: 100 kg ha-1 Urea, 200 kg ha-1 Triple Superphosphate and 100 kg ha-1 Potassium Chloride. The statistical design was a randomized complete block design in factorial arrangement 2 x 4 x 3. Tukey test showed that the inclusion of kudzú in B. decumbens pasture (B2), 2.2 and 3.3 tons CaCO3 ha-1 in B1 and B2, and the fertilization of B1 with Urea and B2 with Triple Superphosphate showed a greater benefit in soil C accumulation and CO2-eq emissions neutralization. Adittional cluster analysis showed that B2 liming with higher lime doses regardless of the type of fertilizer used presented major soil C stored grouped in Cluster 1. We concluded that these soil management factors should be feasible to implement in pastures, that can help offset the negative effects of global climate change on livestock systems at tropical zones.