Soil aggregation and associated organic matter under management systems in sandy-textured soils, subtropical region of Brazil

Abstract

Increasing the diversity of plant species in agricultural production areas favors the maintenance or improvement of soil quality, particularly for soils with a sandy texture. This bene cial effect is related to the formation of aggregates of different origins. This study aimed to i) verify whether soil use and management affect the proportion of biogenic (Bio) and physicogenic (Phy) aggregates, and ii) verify whether biogenic aggregation is more likely to lead to soil improvement than physicogenic aggregation. Three management systems were evaluated (permanent pasture, PP; no-tillage system, NT; and no-tillage + Brachiaria system, NT + B) as well as a reference area (Atlantic Forest biome vegetation, NF). According to their origin or formation pathway, the aggregates were separated, identi ed, and classi ed as Bio (formed by biological processes) and Phy (resulting from chemical and physical actions). Only the PP area promoted greater aggregate formation through Bio. The PP area also increased the total organic carbon (TOC) content of the aggregates and affected the isotopic signal of δ 13 C. The NT + B system provided an increase in the TOC content of its aggregates in comparison with aggregates in the NT and NF areas. Among the formation pathways, the Bio aggregates had the highest TOC and SOM fractions contents and the most negative δ 13 C values. The higher amounts of plant residues in the soil was more important than the diversity of species in favoring the formation of Bio aggregates. The bene cial effect of Brachiaria can also be observed when adopted in consortium with corn in grain production systems.

Organic Carbon Dynamics in Soil From Forest Fragments in the Atlantic Forest and Cerrado Biomes

“…Still, fragment 1 of the Cerrado was the smallest studied, with 55.7 ha, rectangular shape, and the smallest base width; it may be subject to a greater action of the edge effect, starting at the edges of the fragment and spreading to the center of the fragment, which may explain the low C contents in the CF, since the process of change in the community is still incipient in the CF, which leads to a reduction in TOC (Ribeiro et al, 2010;Falcão et al, 2020;Moraes et al, 2021). The process of biomass oxidation by microorganisms in the CF of fragment 1 is possibly faster than the transfer of organic compounds to the soil (Rolo et al, 2018;Pinto et al, 2023;Rosset et al, 2023).…”

Estoques de carbono e nitrogênio e atributos edáficos em cronossequência agricultura-florestas secundárias no Pará

“…Os agregados biogênicos contiveram pelo menos 50% a mais de nitrogênio do que nas amostras de solo. Desta forma, facilitar a formação de agregados biogênicos em solos extremamente arenosos é uma maneira eficiente de aumentar o sequestro de carbono no solo (PINTO et al, 2023), uma vez que a proteção física da matéria orgânica (MO) dentro dos macroagregados é considerada a forma mais suscetível de estabilização do carbono orgânico. Além disso, é importante destacar que os agregados biogênicos são capazes de criar agregados de maneira mais rápida do que outros processos (RODRÍGUEZ et al, 2021).…”