Fostering carbon sequestration in humid tropical and subtropical soils

Description

In the warm and humid tropics and subtropics, conservation agriculture, based on no-tillage and cropping systems with high biomass production, creates a positive balance between the output and input of carbon (C), which increases soil organic C (SOC) stocks by 0.3–0.6 Megagrams per hectare per year (Mg ha-1 yr-1 )in the top 30 cm and in some cases >1.0 Mg ha-1 in the top 1 m of soil. The occlusion of organic matter (OM) inside stable aggregates, facilitated by no-tillage and organo-mineral interactions, are important factors in SOC accumulation, in addition to the high biomass input by crops, such as maize, and by cover crops, including legumes. Lower nitrous oxide emission and higher methane consumption in no-tillage soils reduce the yield-scaled greenhouse gas (GHG) emission compared with conventionally tilled soils. There is potential to foster C sequestration in tropical and subtropical soils, but only when suitable soil and OM management is utilised.

Table of contents

1 Introduction 2 Evolution of conservation agriculture and its impact on soil carbon 3 Carbon stabilisation by organo-mineral interactions in highly weathered soils 4 Greenhouse gas balance at the soil–atmosphere interface 5 Conclusion 6 Where to look for further information 7 References