The Potential of Biochar to Enhance the Water Retention Properties of Sandy Agricultural Soils

Elizaphan Otieno Ndede,Soboda Kurebito,Keiji Jindo,Takeo Tokunari,Olusegun Idowu

doi:10.3390/agronomy12020311

Abstract

The impact of climate change has become increasingly severe in drylands, resulting in heat stress and water deficiency and, consequently, reducing agricultural production. Biochar plays an important role in improving soil fertility. The properties of sandy soils where water deficiency occurs with a greater frequency need to be enhanced by biochar amendments to increase the water retention capacity (WRC). Few studies have reported the effects of biochar on the readily available water (RAW) of these soils or an evaluation of the optimal application rate of the biochar. In this study, we aimed to assess the effect of different biochar types and application rates on the soil properties related to water retention. Under laboratory conditions, we amended sandy soil with four different types of biochar (woodchip (WBC), waterweed of Ludwigia grandiflora (WWBC), poultry litter (PLBC) and bagasse (BBC)) at rates of 0%, 5%, 10%, 15%, 25%, 50%, 75% and 100%. Soils treated with zeolite and perlite, both conventional materials, were arranged for a comparative study. The water content in the amended soils was recorded at saturation, field capacity, wilting point and oven-dry. Our results show a reduction in the bulk density by increasing the amendment rate across all biochar types. Although the WRC increased with the application rate, the RAW reduced and peaked at a 5% (v/v) biochar content for almost all the biochar types. WBC and WWBC showed the highest RAW increments of 165% and 191%, respectively, at a 10% (v/v) rate. In most cases, higher rates (such as 75% (v/v) of PLBC) caused negative effects on the RAW. Following these results, it is clear that both the biochar type and the application rate significantly influence the hydrological properties and the RAW capacity of sandy soils. A 5% (v/v) biochar amendment could significantly improve the readily available water to mitigate drought in sandy agricultural soils.

Highlights

Climate change and the related impacts—for example, drought—have become more severe and widespread across the globe, especially in arid and semi-arid regions (ASALs) [1]
We investigate how sandy soils would interact with varying amounts of biochar from different feedstocks, analyze the resulting impact on the readily available water (RAW) capacity and provide a comparison with the existing soil conditioners zeolite and perlite
PLBC depicted the highest ρb with a considerably low specific surface area compared with that of wood-based biochar types (WBC and WWBC). This could be due to the shape of the biochar particles that were almost even in PLBC but quite rugged in the wood-based biochar types

Summary

Introduction

Climate change and the related impacts—for example, drought—have become more severe and widespread across the globe, especially in arid and semi-arid regions (ASALs) [1]. Average temperatures are generally rising and land and water resources deteriorate daily, resulting in heavy agricultural losses [2]. These situations present most regions with the cruel reality of frequent extreme climate events, associated hunger and rampant poverty. There is an increased need to explore interventions to improve food security amidst these impactful events to save humanity and the planet alike. Emerging concepts such as climate-smart agriculture (CSA) gain traction as nextgeneration interventions to intensify food production with reduced climate impacts. This is an initial step toward the conservation of this diminishing resource

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