Greenhouse gas fluxes in brazilian climate-smart agricultural and livestock systems: A systematic and critical overview

Author(s)

Bieluczyka, Wanderlei Mauricio Roberto ; Cherubin, Mauricio Roberto ; Siqueira-Neto, Carlos Eduardo Pellegrino Cerri Marcos ; Siqueira-Neto, Marcos ; Abdalla-Filho, Adibe Luiz ; Castro, Jose Igor Almeida ; Locatelli, Jorge Luiz ; Tsai, Siu Mui ; de Camargo, Plinio Barbosa

• Document type: Journal article
• Source: JOURNAL OF CLEANER PRODUCTION; v. 464, p. 17-pg., 2024-06-07.

Abstract

Tropical climate-smart agriculture could be a cost-effective and scalable nature-based solution toward achieving net-zero greenhouse gas (GHG) emissions in the coming decades. Nevertheless, the lack of integrated on-farm CO2, CH4, and N2O flux measurements remains a barrier to including these systems in certification programs and the carbon (C) market. This systematic literature review critically examines field-measured GHG emission studies within climate-smart agri-systems in Brazil, aiming to: (i) integrate GHG-measured data, (ii) explore geographical representativeness and connections between organizations and authors, (iii) analyze distributions of studied GHG molecules, climate-smart system types, and productive components, (iv) conduct a meta-analysis on the adoption of climate-smart agriculture, and (v) identify methodological and scope gaps, providing insights for future research directions. The systems considered include no-till, well-managed pasture, integrated croplivestock, and integration with trees (i.e., crop-forestry, livestock-forestry, crop-livestock-forestry, and multistrata agroforestry). Out of 1200 papers mentioning GHGs and climate-smart systems, 74 contained reliable onfarm flux measurements. Most authors were Brazilians affiliated with Embrapa and public Universities. Studies concentrated on the Atlantic Forest and Cerrado, with scarce data for other biomes. Over half of the trials assessed individual GHG molecules and only one climate-smart system. Urochloa spp. and Avena spp. were the most studied forage genera, while soybeans and corn dominated annual crops. Eucalyptus spp. and beef cattle were common trees and animals. No-till, integrated crop-livestock, and agricultural integrations involving trees showed soil C-CH4 influx from 0.8 to 1.0 kg ha-1 y-1. Transitioning from pasture monoculture to integrated systems decreased N-N2O emissions by up to 1.63 kg ha-1 y-1. Converting extensive grazed land to intensifiedintegrated systems reduced animal CH4 intensity, with cuts of up to 122 g CH4 per kg of average daily weight gain. Future research must urgently address methodological issues, such as de-standardization (e.g., 8-10 flux units found per GHG molecule) and the absence of crucial ancillary variables. In conclusion, adopting diversified climate-smart agri-systems shows potential to mitigate GHG emissions, but caution is advised when extrapolating our numerical findings due to limited data across Brazilian edaphoclimatic conditions. We urge scientists to prioritize frequent on-farm measurements of all three GHGs (CO2, N2O, and CH4) along with agroecosystem C sequestration across multiple climate-smart systems, enabling reliable and comparable net GHG flux calculations to identify the most sustainable option. Advancing and standardizing GHG measurements in Brazil offer an opportunity to enhance GHGs inventory accuracy, calibrate models, and promote policies and investments that expand refined tropical climate-smart agriculture. (AU)

• FAPESP's process: 21/10573-4 - Center for Carbon Research in Tropical Agriculture (CCARBON)
• Grantee: Carlos Eduardo Pellegrino Cerri
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 14/50279-4 - Brasil Research Centre for Gas Innovation
• Grantee: Julio Romano Meneghini
• Support Opportunities: Research Grants - Research Centers in Engineering Program
• FAPESP's process: 20/15230-5 - Research Centre for Greenhouse Gas Innovation - RCG2I
• Grantee: Julio Romano Meneghini
• Support Opportunities: Research Grants - Research Centers in Engineering Program