Effect of biochar derived from barley straw on soil physicochemical properties, crop growth, and nitrous oxide emission in an upland field in South Korea

This study was conducted to investigate soil quality, Chinese cabbage growth, and N₂O emission after biochar application in an upland field in South Korea. Each of the barley straw biochar (BC, applied at 10 ton ha⁻¹), inorganic fertilizer (IF, applied at N-P-K = 320–78–198 kg ha⁻¹), and BC + IF treatment areas were separated by a control (Cn) treatment area. Soils treated with BC and BC + IF treatments had lower bulk density and higher porosity than those in the Cn treatment areas. Soil chemical properties (pH, TN, Avail. P₂O₅, and CEC) after biochar addition were improved. In particular, soil pH and CEC related to crop nutrient availability were significantly increased in BC areas compared to those in Cn and IF areas. Fresh weights of Chinese cabbage grown under BC, IF, and BC + IF treatment conditions increased by 64.9, 78.4, and 112.0%, respectively, over that in the Cn treatment area. Total nutrient (TN, TP, and K) uptakes among the treatment areas were, in declining order, BC + IF (14.51 g plant⁻¹) > IF > BC > Cn. More interestingly, the BC application had a positive effect on growth of Chinese cabbage under IF application conditions, and there was a tight relationship between the effect of BC application on Chinese cabbage growth and that of agronomic IF application efficiency. Compared to the IF results, total N₂O flux was lower with BC (flux decreased by 60.6%) or BC + IF (flux decreased by 22.3%) treatments. These results indicate that Chinese cabbage yield, when cultivated in soil conditions such as those in an upland field in South Korea, can be increased by application of BC or a combination of BC and IF.