Biochar Effects on Maize Physiology and Water Capacity of Sandy Subsoil

Sandy soils facilitate maize growth in cold regions. However, Danish coarse sands have poor water and nutrient retention capacity which may constrain crop growth during dry spells. A greenhouse maize experiment was conducted in which straw biochar was applied to the subsoil at concentrations of 0, 1, 2, and 3%. All the plants were fully irrigated until flowering. Thereafter, half of the plants were subjected to drought until 76% of soil water content at field capacity was depleted in the control. Plant height and number of leaves were not significantly different at flowering although significantly lower for 3% biochar at stem elongation stage. Leaf water potential, stomatal conductance as well as photosynthesis and transpiration were maintained in biochar 2 and 3% during the drying cycle reflecting the increase in soil water holding capacity. In the drought treatments, plant biomass tended to be greater for biochar 2% but decreased for biochar 1 and 3%. Cob biomass was increased by biochar 3% but decreased by 1 and 2 %. Biochar however decreased plant biomass and cob biomass under irrigation.