Notice of Retraction Does Adding Wheat Straw Biochar Improve Rape Growth

Biochar addition to soil has been shown to enhance soil quality and crop production. However, little is known about the effect of biochar pyrolysed at different temperatures and added at different rates on soil properties and crop yields. The objective of this study was to investigate the effect of different rates (1%, 5% and 10%) of biochar, produced with wheat straw under different temperatures (200°C, 300°C, 500°C), on soil properties and rape yield in a greenhouse pot experiment. Wheat straw biochar characteristics changed with increasing pyrolysing temperatures. High temperature biochar had high pH and electrical conductivity (EC), and contained more carbon and water-soluble potassium, but less hydrogen, water-soluble nitrogen and phosphorus. Biochar addition to soil resulted in an increase of rape dry matter by 34.0% on average. Rape nitrogen and phosphorus concentrations decreased, and potassium concentrations increased, with increasing rates of biochar addition. Meanwhile, higher rates of added biochar usually resulted in larger increases in soil pH, soil organic matter, soil total nitrogen, soil available phosphorus and soil available potassium. It is concluded that the impact of biochar on either soil or rape plants mainly depends upon the added rate rather than pyrolysis temperature of production.