Impact of MgCl<sub>2</sub> Modified Biochar on Phosphorus and Nitrogen Fractions in Coastal Saline Soil

Abstract

Biochar application is claimed to improve nutrient availability in many problem soils; however, pristine biochars are often reported to produce inconsistent results. Therefore, appropriate biochar modification techniques are required to retain soil nutrients at an optimum level. To increase Nitrogen (N) and Phosphorus (P) availability in coastal saline soil, two slow pyrolyzed biochars viz domestic organic waste (DWB) and farmyard manure (FMB) were modified with MgCl 2 . Ten different treatments comprising the biochars (pristine and modified) with and without the recommended fertilizer were applied (2% w/w) to the soil and incubated for ninety days. The soils were analyzed for pH, EC, available 4 NH + , 3 NO − and different phosphorus fractions sequentially extracted by NH 4 Cl, NaHCO 3 , NaOH, and HCl. During the incubation period, biochar treatments increased all phosphorus and nitrogen fractions than the control and recommended fertilizer treatment. The application of FMB significantly (p < 0.05) increased NH 4 Cl, NaHCO 3 , and NaOH extractable P fractions from DWB, while HCl soluble fraction was enhanced (p > 0.05) by DWB. The increased Al and/or Fe bound phosphate after 60 days of incubation had significant correlations to decreasing soil pH and NaHCO 3 -P, indicating reduced availability with time. Further Mg modification slightly increased P availability only after 60 days of incubation. The modification also improved both nitrogen fractions but significantly (p < 0.05) increased the NO 3 -N content which could be the result of electrostatic attraction between Mg 2+ and 3 NO − ions. Overall, Mg-modified biochar may retain both phosphates and nitrates in soil. However, the magnitude of retention will vary depending on biochar type, nutrient species, and aging in soil.

Effect of Temperature and MgCl2 Concentration on the Catalytic Pyrolysis of Malt Waste Using Response Surface Methodology

“…Regarding possible biochar applications, some works in the literature recommend its use as an adsorbent for the decolorization of reactive dyes, [80–82] supercapacitor, [83] soil conditioner [84] and CO 2 adsorption material [85] . The high HHV of biochar from non‐catalytic pyrolysis of MW can allow its use as a renewable energy source, while the catalytic biochar can be used as soil amendment and a Mg source for the soil [86] …”

“…[85] The high HHV of biochar from non-catalytic pyrolysis of MW can allow its use as a renewable energy source, while the catalytic biochar can be used as soil amendment and a Mg source for the soil. [86]…”

Biochar and Seed Priming Technique with Gallic Acid: An Approach toward Improving Morpho-Anatomical and Physiological Features of Solanum melongena L. under Induced NaCl and Boron Stresses

“…57 Biochar is a biomass of carbon, a low-cost porous pyrogenous matter formed by heating organic waste 58,59 (such as crop deposits or animal manure) under zero or inadequate oxygen environments in a closed furnace at elevated temperatures ≤700 °C through pyrolysis. 60 Biochar is extensively used due to its appropriate carbon content in nutrient-poor and degraded soils. Biochar provides minerals and nutrients (such as Mg, S, Ca, K, and P) and improves soil physical status (such as bulk density, aggregate stability, high cation exchange capacity [CEC], porosity, and saturated hydraulic conductivity).…”

“…Biochar is a biomass of carbon, a low-cost porous pyrogenous matter formed by heating organic waste , (such as crop deposits or animal manure) under zero or inadequate oxygen environments in a closed furnace at elevated temperatures ≤700 °C through pyrolysis . Biochar is extensively used due to its appropriate carbon content in nutrient-poor and degraded soils.…”