Soil Amendment with Biochar Affects Water Drainage and Nutrient Losses by Leaching: Experimental Evidence under Field-Grown Conditions

Leaching of soluble elements from cultivated soils is a major concern to meet the target ofagricultural sustainability in most areas. The effect of biochar application to a cultivated soil on waterdrainage and the consequent solute losses was assessed during a trial carried out over two consecutivegrowing seasons. Biochar was added to a loam-texture soil, at 0, 1, and 2% d.w. rates. A lysimeter-likeset-up arranged in the experimental field-unit, allowed collecting the percolating water. Two multiplelinear regressions (ANCOVA models) were applied to detect biochar effect on: (1) The seasonalamount of drained water; and (2) the concentration of solutes in the drained water. The statisticalcomparison among a set of slope coefficients as affected by treatments (growing season and biochar)was used as modelling approach. The lower biochar application rate (1%) significantly reducedboth the amount of drained water and its concentration in solutes. Conversely, the higher biocharapplication rate (2%) showed no significant effects. Nitrate and chloride showed a significantinteraction with biochar application rates. Higher biochar application increased nitrate leachingwhile reduced that of chloride. Biochar application within a rate no more than 1% resulted in a usefuland quite effective technical operation.