Soil hydrophysical and chemical attributes in ferralsol amended with wood biochar

ABSTRACT

Most studies concerning biochar, which can enhance chemical, physical, and biological soil qualities and increase crop yields, are short-term experiments in controlled environments with temperate regions and sandy soils. Biochar amendment benefits for clayey soils in tropical climate regions are uncertain. Herein, field conditions in clayey soil were investigated for 28 months. Eucalyptus biochar was obtained from charcoal production and incorporated in soil with disc plows (0.00–0.20 m). Treatments comprised six single biochar application amounts–0 (control), 10, 20, 30, 40, and 50 Mg·ha^-1. The experiments were conducted in April 2016, and corn was cultivated in 2016/17 and 2017/18. Soil samples were collected in 2018 for macro/micronutrient, bulk density, porosity, macroporosity, microporosity, water availability, and soil penetration resistance evaluations in the 0.00–0.05-, 0.05–0.10-, 0.10–0.20-, 0.20–0.30-, and 0.30–0.40-m layers. Chemicals P, K and Ca increased compared to the control. The K and Ca increases were related to the biochar composition (6% K and 2% Ca). Soil bulk density decreased by 0.07 kg·dm^-3, and macro/microporosity (total porosity) increased linearly by 2.5% in the 0.05–0.10-m layer with increasing biochar application amount. Soil penetration resistance was unaffected. For each 1 Mg·ha^-1 of biochar applied, a 500-L·ha^-1 increase in available water occurred, which may be important for crops with low water demand and to overcome water restriction periods.

Key words charcoal fines; soil fertility; soil porosity; soil water availability; field experiment