Effect of Biochar Type, Concentration and Washing Conditions on the Germination Parameters of Three Model Crops

Abstract

Biochar has been recognized as a promising and efficient material for soil amendment. However, its effects on seed germination are variable due to its alkaline pH and/or the presence of phytotoxic substances. In this study, two types of biochar (B1 and B2) were mixed with soil at different concentrations (0%, 5%, 10%, 25%, 50% and 100%, w:w), and both the solid and liquid fractions of these mixtures were tested on the germination of basil, lettuce and tomato seeds. Furthermore, solid fractions subjected to a pre-washing treatment (B1W and B2W) were also investigated for their effects on seed germination. Three germination parameters were then measured: seed germination number (GN), radicle length (RL) and germination index (GI). Biochar B2W at 10% increased both RL and GI in basil by 50% and 70%, respectively, while B1 at 25% increased these parameters in tomato by 25%. No effects or negative effects were recorded for lettuce. Liquid fractions (L1 and L2) generally hampered seed germination, suggesting the presence of potentially water-soluble phytotoxic compounds in biochar. These results point to biochar as a suitable component for germination substrates and highlight that germination tests are critical to select the best performing biochar according to the target crop.

Phytotoxicity Removal Technologies for Agricultural Waste as a Growing Media Component: A Review

“…Washing can be categorized into two types based on the type of washing agent used: water washing and chemical washing [129]. Water washing is the simplest and most common method.…”

“…Usually, the higher the concentration of the washing agent, the better the removal effect, but a too-high concentration of the washing agent may cause damage to the material. Therefore, it is necessary to choose a suitable washing agent and dosage based on the characteristics of pollutants and the tolerance of substrates or plants [129]. Moreover, the washing temperature and pH will affect the chemical reaction rate and equilibrium state between pollutants and washing agents [139].…”

Evaluating the Application Potential of Acid-Modified Cotton Straw Biochars in Alkaline Soils Based on Entropy Weight TOPSIS

“…Although its physicochemical properties depend on the raw material, preparation temperature, and preparation method [7,8], biochar generally has a porous structure, a high specific surface area (SSA), and rich surface functional groups. Studies have shown that biochar application can improve soil structure, water and nutrient retention, and fertility [9,10], mitigate abiotic and biotic stresses (e.g., salinity, pollution, and pathogens) in plants [11], and reduce chemical fertilizer application without causing yield loss [12][13][14][15][16][17][18][19]. Biochar generally has a high pH and thereby is alkaline in nature.…”