Can highly weathered soils under conservation agriculture be C saturated?
| Autor: | Florent Tivet, Julio Cezar Franchini, Daiani da Cruz Hartman, João Carlos de Moraes Sá, Juliane Zuffo dos Santos, Rafael Schimiguel, Rattan Lal, Ademir de Oliveira Ferreira, Clever Briedis |
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| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
Agroecosystem
P33 - Chimie et physique du sol 010504 meteorology & atmospheric sciences P40 - Météorologie et climatologie F08 - Systèmes et modes de culture agroécologie adaptation aux changements climatiques Soil science 01 natural sciences Nutrient Fertilité du sol Agriculture durable Matière organique 0105 earth and related environmental sciences Earth-Surface Processes Changement climatique Utilisation des terres Impact sur l'environnement 04 agricultural and veterinary sciences Soil carbon Soil quality séquestration du carbone Pratique culturale Oxisol réduction des émissions Soil water 040103 agronomy & agriculture 0401 agriculture forestry and fisheries Environmental science Soil horizon P01 - Conservation de la nature et ressources foncières Saturation (chemistry) Cycle du carbone Gaz à effet de serre |
| Zdroj: | Catena |
| Popis: | Soil organic carbon (SOC) plays an essential function in global agroecosystems. Conservation agriculture (CA) associated with diverse and high C-input is an important tool to increase SOC, improve soil quality, and increase agronomic productivity. However, the information about the potential of highly weathered soils under CA to accumulate SOC, and when the SOC saturation may occur, is scarce. This study was based on the hypothesis that in highly weathered soil from tropical and subtropical agro-ecosystems, the potential to store SOC lies more in the sub-soil than in surface layers and is determined by nutrient scarcity. Thus, the aim of this study, performed in a long-term incubation experiment (30 months), was to: (i) assess the SOC flow and mineralization based on CO 2 -C emissions for estimating SOC accumulation; (ii) evaluate the impact of nutrient scarcity on C accumulation efficiency by soil layers; and (iii) determine when C saturation occurs in these soils. The incubation study was performed in three Brazilian Oxisols under long-term CA, and was comprised of four amounts of C-inputs (0, 6, 12 and 24 Mg C ha − 1 ) added at 0, 10 and 20-months to three soil layers (0–20, 20–40 and 40–100 cm). The CO 2 -C emission was 19.0, 9.0 and 7.0% higher in the 0–20 cm than that in 40–100 cm layer for Ponta Grossa, Londrina and Lucas do Rio Verde sites, respectively, which was associated with higher antecedent SOC content and fertility status. A higher SOC accumulation efficiency was observed for the 0–20 cm layer than in deeper layers. Nutrient scarcity in deep soil layers; especially that of P, Ca 2 + and Mg 2 + ; was the driving force limiting SOC accumulation. Carbon saturation was not achieved indicating a high SOC storage capacity in these soils. Because these and similar soils cover a large global area, they possess a large C sink to mitigate atmospheric CO 2 -C . The potential SOC storage estimated for 20–100 cm layer based on this study and upscaling for 1/3 Brazilian Oxisols (100 million ha) may offset 0.06 to 0.36 Pg C yr − 1 or 5.5% to 32.7% of the global annual greenhouse gas emissions by land use change. |
| Databáze: | OpenAIRE |
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