Explaining the Water-Holding Capacity of Biochar by Scanning Electron Microscope Images

Abstract

Biochar is a solid material formed during biomass thermochemical decomposition processes. This organic compound has particular properties that may cause effects on soils depending on its feedstock and processing conditions. Thus, the characteristics and purpose of use of this material must be recognized prior to its use. Two types of biochar, derived from different wood sources, were compared, one from caatinga biome species and another from cashew trees. Two species from caatinga biome were used, jurema-preta (Mimosa tenuiflora Willd. Poir.), and marmeleiro (Croton sonderianus Müll. Arg.). This study aimed to identify the best biochar material regionally available to increase water-holding capacity in the soil, based on laboratory tests and microstructural porosity evaluation. Biochar from Caatinga wood demonstrated an improved water-holding capacity if compared to cashew wood biochar. The particle diameters of 2 and 4 mm showed the highest levels, which were 2,268 g.g-1 for caatinga wood and 0.574 g.g-1 for cashew wood biochars, respectively. While the smaller quantities of macropores and a larger number of micropores (smaller radius) could explain the higher water-holding capacity for biochar from caatinga wood, the thick lignified cell walls of biochar from cashew wood support the idea of a hydrophobic effect contributing to water lower holding capacity.

Lignoceliuliozinės žematemperatūrės bioanglies hidrofiliškumo didinimo tyrimai ir technologijos kūrimas

“…Koreliacijos koeficientas šio modelio atveju siekė 0,87 (3.5 lentelė). Remiantis kitu tyrimu (Gondim et al, 2018), bioanglies VSG taip pat gali būti Y = 1,508 + (0,27 × P);…”

Hydrophilic Polymer Changes the Water Demand in the Implementation of a Dwarf Cashew Orchard

“…The result of the chemical analysis of the cashew wood biochar is shown in Table 1. Water retention capacity, determined in a Hainnes funnel at the field capacity (10 kPa), was 0.53 and 0.57 g g −1 for particle size diameters of 4 and 2 mm, respectively (Gondim et al, 2018). Both the biochar and the polymer were applied dry and at the pit.…”

Biochar‐based land development

“…Water remains in plant-available form in the internal micrometer-scale porosity that consequently increases the water retention ability of soil (Rasa et al, 2018).Willow biochar with the internal pore size of 10-50 μm (equivalent pore diameter) could enhance the pore size and plant available water in heavy clay soil (Rasa et al, 2018). Smaller quantities of macropores and larger micropores could explain such an increase in WRC (Gondim et al, 2018). For cashew wood biochar, the highest level of WRC was recorded with a particle diameter of 4 mm (Gondim et al, 2018), while in another experiment in Californian, soil higher field capacity was with 1-2 mm particle size of walnut biochar (Wang et al, 2019).…”

“…Smaller quantities of macropores and larger micropores could explain such an increase in WRC (Gondim et al, 2018). For cashew wood biochar, the highest level of WRC was recorded with a particle diameter of 4 mm (Gondim et al, 2018), while in another experiment in Californian, soil higher field capacity was with 1-2 mm particle size of walnut biochar (Wang et al, 2019). One estimate involving 166 specific combinations of various biochar and soil properties revealed a 0.26% increase in WRC per t ha À1 of the biochar addition.…”