Effects of Biochars Treated with Peroxide and Montmorillonite on Aggregation and Water Retention in a Mexican Clayey Soil.

Water supply shortage due to limited and uneven precipitation patterns in central Mexico is problematic to severely affect crop yields. Soils in Guanajuato are clayey, which are expansive with easily losable moisture resulting in crumbly soils that can reduce capacity of water retention (WR) and soil stability. Biochar (BC) is a carbon-rich material pyrolysed by feedstock biomass with limited oxygen. Nowadays, biochars have been designed to possess specific properties enhancing important biochar’s parameters such as cation exchange capacity, surface area, and water retention capacity. Treatments such as oxidizing with hydrogen peroxide (PE) and/or mixing clay with feedstock have been widely used to achieve such properties. This study evaluated effects of soil application of biochar derived from “Agave tequiliana”, treated with PE and montmorillonite (CL) on water retention and soil aggregation. Air-dried Haplic Phaeozem soil was repacked into 100 mL cylinder with six different types of BC; normal BC, PE and CL, each under two pyrolysis temperatures of 400 and 800^oC. Applications rate of BC was 3% (w/w). Water retention curve (WRC) using pressure plate apparatus was developed. Water resistant soil aggregates were analyzed by wet sieving method on different incubation periods of 7, 14, 21 and 28 d. BC400-PE has obtained the highest water content than other treatments and control until pF 3.0 followed by BC400 and control. If compared the pyrolysis temperature and its respective treatments, 400^oC has obtained highest water content than 800^oC. Experiment will be continued until pF 4.2.