Structure alteration of a sandy-clay soil by biochar amendments

Abstract

Purpose The aim of the present study was to investigate structure alterations of a sandy-clay soil upon addition of different amounts of biochar (f bc ). Materials and methods All the f bc samples were analyzed by high energy moisture characteristic (HEMC) technique and 1 H nuclear magnetic resonance (NMR) relaxometry. HEMC was applied in order to evaluate aggregate stability of biocharamended soil samples. 1 H NMR relaxometry experiments were conducted for the evaluation of the pore distributions through the investigation of water dynamics of the same samples.Results and discussion The HEMC technique revealed improvement in aggregate stability through measurements of the amount of drainable pores and the stability ratio. The latter increased as the amount of biochar was raised up. The 1 H NMR relaxometry revealed a unimodal T 1 distribution for both the sole sandy-clay soil and the biochar. Conversely, a bimodal T 1 distribution was acquired for all the different f bc samples. Conclusions Improvement in aggregate stability was obtained as biochar was progressively added to the sandy-clay soil. A dual mechanism of water retention has been hypothesized. In particular, intra-aggregate porosity was indicated as the main responsible for molecular water diffusion when f bc comprised between 0 and 0.33. Conversely, inter-aggregate porosity resulted predominant, through swelling processes, when f bc overcame 0.33.

Biochar and Water Quality

“…Biochar particles often have lower density than soil particles (Blanco‐Canqui, 2017). Biochar can also decrease soil bulk density and increase porosity by improving soil aggregation (Baiamonte et al, 2015). Pyrolysis at increasing temperatures increases the internal porosity (i.e., micropore space) of the biochar.…”

“…Studies have found that biochar application can increase wet aggregate stability by 3 to 226% (Blanco‐Canqui, 2017). The high variability in biochar effectiveness on increasing aggregate stability can be attributed to differences in soil texture and biochar particle size (Baiamonte et al, 2015; Blanco‐Canqui, 2017). Addition of fine biochar can enhance aggregation more in sandy soils than in silty clay and clayey soils.…”

“…Similarly, Liu et al (2014) reported that C concentration for corn ( Zea may s L.) cob biochar increased from 67 to 88% when pyrolysis temperature increased from 300 to 600°C. Literature review suggests that the biochar‐induced soil C concentration can promote soil aggregation and reduce soil erodibility, but the C concentration in biochar can vary with biochar properties (e.g., pyrolysis temperature; Jien and Wang, 2013; Baiamonte et al, 2015). …”

Effects of conocarpus biochar on hydraulic properties of calcareous sandy soil: influence of particle size and application depth

“…These effects of biochar application, however, depend on various factors such as the soil types, the type of feedstocks used for charring, pyrolysis conditions and the amount of biochar applied to the soils (Abel et al 2013;Glaser et al 2002; Barnes et al 2014). In this context, Baiamonte et al (2015) found that the incorporation of biochar into the sandy-clay soil increased soil aggregate stability by improving the porosity, the field capacity, and the maximum available water.…”

Natural and anthropogenic pyrogenic carbon in Mediterranean ecosystems: the need for interdisciplinary learning and collaboration

“…Applying the high-energy moisture characteristic (HEMC) technique and the powerful 1 H nuclear magnetic resonance (NMR) relaxometry to evaluate changes in aggregate stability and pore size distribution of biochar-amended soils, Baiamonte et al (2014) showed that aggregate stability improved as a biochar was progressively added to a sandy-clay soil. Since the recognition of the interaction mechanisms between water and biochar is of paramount importance to understand why biochar soil amendments improve soil fertility and crop production, a more detailed analysis of the 1 H NMR relaxation was performed.…”