Effect of biochar on N2O emission, crop yield and properties of Stagnic Luvisol in a field experiment.

Soils are one of the main sources of nitrous oxide (N₂O) in agriculture. Soil management practices can significantly affect N₂O emissions through changing soil physical, chemical and biochemical properties. Application of biochar to arable soils can be an option for N₂O emission mitigation, but the effect of biochar can be different for soils with different fertility levels. The objective of this study was to evaluate the effect of biochar application on N₂O emission, soil properties and barley yield from loamy sand Stagnic Luvisol with high and medium levels of fertility caused by high rates of farmyard manure and fertilizer application for 10 years. A small-scale field experiment was conducted during the growing season of 2012 in North-Western Russia. Four treatments were used in the experiment: 1) control (no biochar, no N-fertilizer), 2) biochar (12 t ha^-1), 3) N-fertilizer (90 kg ha^-1 N) and 4) biochar (12 t ha^-1) + N-fertilizer (90 kg ha^-1 N), in five replicates. Significant changes in water-holding capacity and the amount of available nitrogen (N) occurred in the soil with high fertility, and thus it emitted significantly more N₂O for the growing season than the soil with medium fertility. Biochar application effect on N₂O emissions depended on the soil management history and was reducing the emission from the soil with high fertility rich in mineral N and C but not from the soil with medium fertility if no nitrogen fertilizer was applied to the latter soil. The yield-scaled N₂O emission was the highest from the control treatments for the soil with both fertility levels, and the soil with high fertility was always characterized by higher yield-scaled N₂O emissions than the soil with medium fertility. Application of biochar reduced yield-scaled N₂O emission from the soil with medium and high fertility levels showing that biochar application to the soil can improve N use by the plants. [ABSTRACT FROM AUTHOR]