Abstract

Leaching of NO₃ has been shown to be a major problem in coarse-textured sandy soils. It has been suggested that biochar application to sandy soils could reduce leaching of NO₃. However, how biochar could be used to provide short-term NO₃ leaching reduction in sandy soils has received little research attention. Therefore, the aim of this study was to determine if and how biochar could be used to reduce NO₃ leaching from artificial columns of sand (sandy soil). To achieve this, a simple assay was developed in a controlled temperature room to assess the short-term impacts of biochar on NO₃ leaching from a column containing sand. The capacity to pick-up variations in NO₃ leaching pattern from the sand columns based on the concentrations of the NO₃ solutions used to perfuse the sand columns, as well as, the rate at which these solutions were perfused through the sand columns using this approach was initially established. A pulse chase experiment showed that the NO₃ was very mobile, and once the supply was removed, the column of sand rapidly lost the NO₃. The exception appears to the inclusion of biochar where this process is slowed down, but eventually the sand column lost all the NO₃. When oak biochar produced through high temperature pyrolysis (500-600 ^oC) by a commercial producer (Humko, d.o.o., Bled Sheenjek, Slovenija) was applied to the sand columns at a rate of 10% (w/w), the pattern of NO₃ leaching was modified. Biochar appeared to delay NO₃ leaching from the sand. The extent of this delay, and how it may influence NO₃ availability in the soil for plant uptake requires further research.

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