Restoring soil carbon and chemical properties through silvopastoral adoption in the Colombian Amazon region

Abstract

Silvopastoral systems (SPS) have been widely implemented in the Colombian Amazon region to improve pastures involving a greater diversity of species, soil tillage, fertilization, and higher stocking rate, which can induce changes in soil properties and functions. This study aimed to evaluate soil chemical properties and carbon sequestration changes due to the transition from traditional pastures to silvopastoral systems. The study was conducted in the Colombian Amazon region, specifically in La Montañita and El Doncello Counties, in Caquetá, the second most important hotspot of deforestation in the entire Amazon basin. In each study site, we established a chronosequence consisting of three areas following the typical land‐use change at the region: (i) native vegetation, (ii) traditional pasture, and (iii) silvopastoral system. We found that agricultural practices involving liming and tillage, performed under the silvopastoral management, contributed to reducing soil active acidity and exchangeable acidity with soil pH increasing from 3.8 to 4.3 and H++Al3+ decreasing from 5.8 to 2.3 cmolc kg−1. These alterations favored increases in Ca2+ and Mg2+ contents mainly, increasing the base saturation from 17% in traditional pastures to 55% under silvopastoral systems. The synergic effect of the mix of grasses and trees under silvopastoral management improved soil micronutrient contents and modified soil C stocks in 20–30 cm layer. A rate of soil C accretion of 0.26 Mg ha−1 yr−1 for the 0–30 cm detected in silvopastoral systems suggests that its implementation could be a promising tool for C sequestration in tropical regions, capable of restoring soil functioning of degraded areas.

Soil enzyme responses to land use change in the tropical rainforest of the Colombian Amazon region

“…Those variable soil C and N responses to land transition from forest to pasture corroborate previous studies in the Amazon region [ 14 , 16 , 37 – 41 ]. In hill landscape the pasturelands are under long-term continuous grazing and poor pasture/soil management practices resulting in reduced C inputs to soil and soil health degradation as previously reported in the Colombian Amazon region [ 14 ].…”

“…[ 49 ] and Olaya‐Montes et al . [ 14 ] in Amazon soils. Highly-weathered tropical soils, rich in Fe and Al oxides in clay fraction, can adsorb large amounts of P as insoluble phosphate [ 50 , 51 ], limiting the availability of inorganic P for plants [ 48 ].…”

“…In the Amazon region, intensive deforestation of native rainforest for expansion of livestock and agricultural activities has led to significant changes of soil C stocks, and degradation of soil physico-chemical properties in many regions [ 12 – 15 ]. Particularly, soil health degradation and soil C declines were substantial in pasture systems with low-fertility soils [ 14 – 16 ]. It is also well established that replacing native rainforest diminishes quantity and quality of organic matter input to the soil, the primary source of microbial resources (e.g., C, N, S, P), and, therefore, significantly shifting soil microbial communities [ 17 – 19 ].…”

Browse from Three Tree Legumes Increases Forage Production for Cattle in a Silvopastoral System in the Southwest Amazon

“…There is increased impetus to evaluate novel tree species that can contribute to resilient livestock production systems that both adapt to and mitigate climatic change and prevent further losses in biodiversity and forest cover [ 6 ]. The benefits of trees in pastures can include enhanced soil nutrient cycling and soil formation, increased rate of recovery of compacted soils, reduction in water and nutrient runoff and soil erosion, additional habitat to support biodiversity, mitigation of climate change via carbon sequestration and increased ecological connectivity [ 7 , 8 , 9 , 10 ]. In the tropics, trees planted in pastures also provide shade which can reduce heat stress.…”

Table_1.DOCX

“…A. Improved chemical soil health: Fisher et al, 1994;Schultze-Kraft et al, 2018;Baptistella et al, 2020;Lira et al, 2020;Olaya-Montes et al, 2020;Vazquez et al, 2020B. Improved physical properties: Schultze-Kraft et al, 2018Baptistella et al, 2020;Boddey et al, 2020 C. Increased below-ground biodiversity and biological activity: Byrnes et al, 2017;Boddey et al, 2020;Vazquez et al, 2020…”