Miscanthus Biochar had Limited Effects on Soil Physical Properties, Microbial Biomass, and Grain Yield in a Four-Year Field Experiment in Norway

Adam O’Toole,Christophe Moni,Monique Carnol,Daniel Rasse,Bernard Bosman,Anne Schols,Simon Weldon

doi:10.3390/agriculture8110171

Abstract

The application of biochar to soils is a promising technique for increasing soil organic C and offsetting GHG emissions. However, large-scale adoption by farmers will likely require the proof of its utility to improve plant growth and soil quality. In this context, we conducted a four-year field experiment between October 2010 to October 2014 on a fertile silty clay loam Albeluvisol in Norway to assess the impact of biochar on soil physical properties, soil microbial biomass, and oat and barley yield. The following treatments were included: Control (soil), miscanthus biochar 8 t C ha−1 (BC8), miscanthus straw feedstock 8 t C ha−1 (MC8), and miscanthus biochar 25 t C ha−1 (BC25). Average volumetric water content at field capacity was significantly higher in BC25 when compared to the control due to changes in BD and total porosity. The biochar amendment had no effect on soil aggregate (2–6 mm) stability, pore size distribution, penetration resistance, soil microbial biomass C and N, and basal respiration. Biochar did not alter crop yields of oat and barley during the four growing seasons. In order to realize biochar’s climate mitigation potential, we suggest future research and development efforts should focus on improving the agronomic utility of biochar in engineered fertilizer and soil amendment products.

Highlights

The challenge of producing more food for a growing world population while mitigating climate change demands new solutions for managing agricultural systems [1]
There were no significant differences between the treatments in soil bulk density and porosity in
Bulk density was significantly lower by 7% in biochar 25 t C ha−1 (BC25) in 2014 compared to the control while the lower dose treatment (BC8) did not differ from the control (Table 2)

Summary

Introduction

The challenge of producing more food for a growing world population while mitigating climate change demands new solutions for managing agricultural systems [1]. The application of biochar to soil has received increasing attention as an alternative method for increasing long-term soil carbon levels while potentially improving soil quality and crop productivity [2]. Biochar is the term given to charcoal or carbonized biomass when it is used for the purpose of soil carbon sequestration and for improving soil fertility [3]. Meta-analyses confirm that biochar can improve soil physical and hydrological functioning [4] and can reduce N2 O and CH4 emissions [5,6]. Biochar has been shown to increase crop yields on average by 25% in the tropics but has had no effect in temperate regions [7]. In Norway, biochar application is recognized as one of several methods with

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