Health Assessment in Water-Logged Soil Cultivated to Rice under Amendment with Rice Straw Biochar, Magnetic Rice Straw Biochar, and their Urea Intercalated Derivatives

Abstract

Waterlogged soils under rice cultivation often exhibit impaired soil health due to anaerobic conditions that alter microbial dynamics and nutrient cycling. Biochar amendment has been proposed as a strategy to improve soil health under such conditions. This study assessed soil health in waterlogged soil cultivated to rice following amendment with rice straw biochar (RSB), magnetic rice straw biochar (MRSB), urea-intercalated rice straw biochar (URSB) and urea-intercalated magnetic rice straw biochar (UMRSB). A pot experiment was conducted in a Completely Randomized Design (CRD) with five treatments including an unamended control. Soil health indicators assessed included microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), dissolved organic carbon (DOC), dissolved organic nitrogen (DON) and urease activity. Results showed that MRSB and UMRSB amendments significantly (p ≤ 0.05) increased MBC, MBN and urease activity compared to the control and plain RSB treatment. DOC and DON values were highest in URSB-amended soils. The magnetic modifications of rice straw biochar showed superior capacity to improve biological indicators of soil health in waterlogged paddy soils, suggesting their potential application in sustainable rice production systems.