Abstract

The reclamation of degraded pastures has a prominent role in the Brazilian climate policy and is one of the main strategies of Brazil's Low-Carbon Agriculture Plan (ABC Plan). Here, we aimed to evaluate the changes in soil C and N stocks in livestock areas under pasture reclamation and contribute to the empirical basis for evaluating the ABC Plan. Based on the assessment of six chronosequences across Brazilian Cerrado, we observed that the effects of management practices for pasture reclamation on soil C and N stocks in livestock areas were quite variable. Any general tendencies depend on the depth evaluated. At the 0–30 cm soil layer, pasture areas under reclamation in Brazilian Cerrado showed an average soil C change rate of 0.47 Mg C ha⁻¹yr⁻¹. However, for the more in-depth assessment (0–100 cm), the adoption of management practices for pasture reclamation did not affect the average rate of soil C changes for these areas. In this sense, we suggest that an up-scaling from single case studies may lead to overestimations of soil C inventories. Thefore, ABC Plan must review some of its approaches based on general values and extrapolations regarding C sequestration in pasture areas.

摘要

退化牧场的开垦在巴西气候政策中占有突出地位，是巴西低碳农业计划（ABC计划）的主要战略之一。在这里，我们旨在评估牧场开垦畜牧区土壤碳和氮库的变化，并为评估 ABC 计划提供经验基础。基于对巴西塞拉多六个时间序列的评估，我们观察到牧场开垦管理实践对畜牧区土壤碳和氮储量的影响差异很大。任何一般趋势都取决于评估的深度。在 0-30 cm 土层，巴西塞拉多开垦牧场的平均土壤碳变化率为 0.47 Mg C ha ^-1 yr ^-1. 然而，对于更深入的评估（0-100 厘米），牧场开垦管理实践的采用并未影响这些地区土壤碳变化的平均速率。从这个意义上说，我们建议从单一案例研究中扩大规模可能会导致土壤碳库存的高估。因此，ABC 计划必须根据有关牧场地区碳封存的一般价值和推断来审查其某些方法。