Impact of Organic Vegetable System on Soil Organic Matter Pools and CO₂ Emission in the Tropical Region

ABSTRACT

It is widely recognized that the input of organic matter in tropical agriculture is essential to maintain productivity and soil quality. This study aimed to investigate the dynamics of organic C pools and CO₂ emission influenced by organic compost fertilization and leucaena biomass in an area of 6 years under organic farming. The system consisted of 5 treatments based on 5 levels of fertilization with organic compost (0, 10, 20, 30, and 40 t ha⁻¹). Each block was surrounded by leucaena and their pruning’s were distributed in equal proportions for all treatments. Two rotating crops were performed per year, cabbage/corn. Soil samples were collected in the 0–10 and 10–20 cm layers in 2-year seasons. TOC and N stocks were between 23.1 and 51.6 t ha⁻¹, and 2.1 and 5.4 t ha⁻¹, respectively. The highest compost doses increased the microbial biomass C and N. The increase in microbial biomass was followed by higher emissions of C-CO₂. Increased microbial quotient values indicated C accumulation in the system by a higher amount of active metabolic C. The microbial biomass was less efficient in the use of the high organic compost doses. The dose of compost should be reduced and applied constantly by the farmers to attend the plant demand by nutrients and increase the efficiency of C sequestration in the soil. This C sequestration will also improve biological activity and soil quality in tropical regions, increasing food production.

KEYWORDS:

• Agroforestry system
• composting
• Green manure
• organic fractions

Acknowledgements

The authors thank INCAPER (Espírito Santo Institute for Research, Technical Assistance and Rural Extension) for the study in partnership, the Brazilian sponsors CAPES (Coordination of Improvement of Personal Higher Education), CNPq (National Counsel of Technological and Scientific Development) and FAPES (Foundation for Research Support of the State of Espírito Santo) for granting financial support and scholarships.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

The work was supported by the FAPES (Foundation for Research Support of the State of Espírito Santo) CNPq (National Counsel of Technological and Scientific Development).