Novel approaches to remediate soil water repellency

Soil water repellency (SWR) represents a major challenge to agro-ecological systems, contributing to soil and water degradation and impacting biological productivity. This study evaluated three bioremediation approaches to mitigate SWR: (i) microbial remediation using Rhodococcus sp., both individually and in combination with biochar (2%) and clay (2%); (ii) enzymatic treatments using α-amylase, laccase, and protease; and (iii) the application of spent mushroom substrate (SMS), in both dry sieved form and as an extract. Treatments were applied to severely water-repellent soils, with results monitored over a three-month incubation period. The findings revealed that combining clay, biochar, and microbial inoculants was highly effective in eliminating SWR, reducing the initial molarity of ethanol droplet (MED) values of 3.4 M (in YM soil), 3.4 M (in ME soil), and 2.4 M (in SV soil) to 0 M (no detectable SWR by the MED test) after three months. Enzymatic treatments also significantly decreased SWR, with laccase being the most effective, reducing MED from 3.4 to 0.2 M. The addition of SMS, particularly at 2%, further reduced SWR, with dry SMS reducing MED to 1.0 M in both YM and ME soils after three months, and the SMS extract lowering MED to 0.8 and 0.6 M in YM and ME soils, respectively. These findings highlight the potential of using natural, sustainable methods such as microbial inoculation, enzymes, and SMS to effectively reduce SWR and improve soil health.