Water retention in sandy soils of different origins with the addition of biochar

Abstract

This study evaluated biochar influence on water retention in sandy soils with different source materials. Samples from Horizon A of six profiles of Neossolos Quartzarênicos (Salto das Nuvens, Utiariti, Pantanal, Coberturas Detrito Lateríticas Ferruginosas, Botucatu e Bauru formations), collected in different regions of the state of Mato Grosso, Brazil, were used to determine the hydro-physical characteristics with the addition of biochar. The biochars assessed were produced from two sources of raw material (sugarcane filter cake and cotton husks) under pyrolysis at a temperature of 400 °C. Retention curves for soils with and without biochar, the field capacity, permanent wilting point, available water in the soil, total porosity, macroporosity, and microporosity were determined. The results evidenced that the application of biochar increases the microporosity (86.7% with cotton husks biochar and 67.9% with filter cake biochar) and reduces the microporosity of sandy soils (38.2% with cotton husks biochar and 36.0% with filter cake biochar); also, there was a higher increase in water availability with biochar from cotton husks (57.1%). There was an increase in soil microporosity and a reduction in macroporosity due to the influence of biochar addition in the sandy soils from the Salto das Nuvens, Utiariti, Pantanal e Coberturas Detrito Lateríticas ferruginosas, with no changes in the Botucatu and Bauru Formations. Biochar increases water retention in sandy soils; however, this does not occur for all geological formations studied.