Legume silvopastoral systems enhance soil organic matter quality in a subhumid tropical environment

Abstract

The silvopastoral system avoids the degradation of tropical grasslands by providing essential nutrients to the soil while improving livestock diet and farmer's income by increasing the marketable wood supply. We hypothesize that intercropping shrub‐tree legumes into signalgrass increases microbial activity and soil organic matter (SOM) quality. We investigated silvopastoral system soils over 5 yr in a subhumid climate in northeastern Brazil to determine the total C and N contents and to estimate C‐microbial biomass and respiration, microbial and metabolic quotients, humic acid (HA), and fulvic acid (FA). The experimental design evaluated (a) signalgrass intercropped with gliricidia at 0, 4, and 8 m from the center of the double legume row; (b) signalgrass intercropped with sabia at 0, 4, and 8 m from the center of the double legume row; and (c) single signalgrass. Samples were obtained after 2, 3, 4, and 5 yr from silvopastoral system implementation. The shrub‐tree legumes soils had total C (39 g kg−1) and total N (3.8 g kg−1) contents significantly higher (30 and 72%, respectively) than single signalgrass soil only on the fifth year after establishment. Microbial biomass C at 0 and 4 m from the legume's rows was 700 mg kg−1, which was 75% higher than single signalgrass soils. There was strong microbial respiration (∼50 mg C‐CO2 kg−1 d−1) in legumes soils, but the metabolic quotient did not indicate disturbance in microbial activity. The microbial quotients were significantly higher in shrub‐tree legumes soil, and the HA/FA ratio was nearly 1, demonstrating greater efficiency in SOM decomposition by microbial activity. Overall, 5 yr after establishment, the silvopastoral system has improved SOM quality and contributed to grassland sustainability.

Influence of land use and different plant residues on isotopic carbon distribution of total and water extractable organic matter in an incubation experiment with weathered tropical soil

“…The intensive cultivation and monoculture succession cause land degradation, loss of organic carbon and biodiversity, and social constraints (FAO, 2015; Ferrante & Fearnside, 2022). The recovery of overexploited soils may be faced with low input cropping practices that heighten the SOM as a determinant variable to support sustainable crop productivity (Canellas et al, 2014; Lira Junior et al, 2020). Understanding the dynamics of SOM related to land use and OM input is a keystone for the restoration of degraded and altered ecosystems and enhances food security, water supply, and biodiversity.…”

Realizing Livelihood and Environmental Benefits of Forages in Tropical Crop-Tree-Livestock Systems

“…SPS consist of diverse agroforestry arrangements that combine herbaceous plants, shrubs and trees for animal nutrition and complementary uses like timber or fruit production (Murgueitio et al, 2011). In particular, SPS with tree legumes are a promising nature-based solution to reduce the environmental impact of cattle production, while increasing its productivity, especially in Latin America Chará et al, 2018;Landholm et al, 2019;Arango et al, 2020;Lira Junior et al, 2020). SPS arrangements might be in the form of scattered trees in pastures, pastures within tree alleys, living fences and windbreaks surrounding a pasture, to name a few (Murgueitio and Ibrahim, 2001;Murgueitio et al, 2011;Chará et al, 2018).…”

Promoting Forage Legume–Pollinator Interactions: Integrating Crop Pollination Management, Native Beekeeping and Silvopastoral Systems in Tropical Latin America

“…SPS consist of diverse agroforestry arrangements that combine herbaceous plants, shrubs and trees for animal nutrition and complementary uses like timber or fruit production (Murgueitio et al, 2011). In particular, SPS with tree legumes are a promising nature-based solution to reduce the environmental impact of cattle production, while increasing its productivity, especially in Latin America (Dubeux et al, 2017;Chará et al, 2018;Landholm et al, 2019;Arango et al, 2020;Lira Junior et al, 2020). SPS arrangements might be in the form of scattered trees in pastures, pastures within tree alleys, living fences and windbreaks surrounding a pasture, to name a few (Murgueitio and Ibrahim, 2001;Murgueitio et al, 2011;Chará et al, 2018).…”