Biochar Amendment Enhances Water Retention in a Tropical Sandy Soil

Martha Lustosa Carvalho,Maurício Roberto Cherubin,Moacir Tuzzin De Moraes,Carlos Eduardo P Cerri

doi:10.3390/agriculture10030062

Martha Lustosa Carvalho, Maurício Roberto Cherubin + Show 2 more

Open Access

https://doi.org/10.3390/agriculture10030062

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Abstract

The use of biochar, which is the solid product of biomass pyrolysis, in agricultural soils, has been shown as a strategic solution for building soil carbon stocks and mitigating greenhouse gas emissions. However, biochar amendment might also benefit other key soil processes and services, such as those that are related to water retention, particularly in sandy soils. Here, we conducted an experiment to investigate the potential of biochar to enhance pore size distribution and water retention properties in a tropical sandy soil. Three biochar rates were incorporated (equivalent to 6.25, 12.5, and 25 Mg ha−1) into plastic pots containing a sandy Oxisol sampled from a sugarcane field in Brazil. Undisturbed samples of the mixture were collected at two evaluation times (50 and 150 days) and used to determine water retention curves and other soil physical properties. The results showed that biochar amendment decreased soil bulk density and increased water retention capacity, micropore volume, and available water content. Higher soil water retention in amended soil is associated with the inherent characteristics of biochar (e.g., internal porosity) and potential improvements in soil structure. Microporosity and water retention were enhanced with intermediate biochar rate (12.5 Mg ha−1), instead of the highest rate (25 Mg ha−1) tested. Further studies are needed to validate these results under field conditions.

Highlights

Climate-smart agriculture is critical for achieving food and energy security and mitigating global warming and climate change [1,2]
We investigated the impact of biochar amendment on pore function and water retention properties in a tropical sandy soil
Biochar amendment promoted a reduction of soil bulk density as compared to control (Figure 1)

Summary

Introduction

Climate-smart agriculture is critical for achieving food and energy security and mitigating global warming and climate change [1,2]. Agricultural activities (e.g., land use change, soil tillage, and use of synthetic N fertilizers) account for 14% of greenhouse gas (GHG) emissions of anthropogenic origin [3,4], which has intensified alterations in the planet’s hydrological regimes in response to global climate change [5,6]. These modifications may bring new challenges for food production in some areas, including Brazil, where more than 80% of production areas are rainfed [7].

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