Objective  Effects of adding biochar in soil on the growth and nutrient-uptake of continuous monocropped cucumber plants were studied.

  Methods  A pot experiment was performed on cucumber seedlings grown in soil without (CK) or with various concentrations of biochar at 0.5%, 1%, 2%, and 3%. Growth and nutrients absorption by the plants were monitored to determine the effects and optimal application of the soil conditioner.

  Results  The fresh and dry weights as well as the nitrogen, phosphorus, and potassium contents of the cucumber seedlings increased significantly as the amount of added biochar increased but declined at higher levels of the addition. With 1% added biochar in soil, the biomass and the contents of nitrogen, phosphorus, and potassium in the plants peaked. The pH and organic carbons in soil underwent an upward trend with increasing biochar. Compared to CK, adding 2% biochar to the potting soil significantly improved the contents of available potassium, 2% and 3% significantly elevated that of available phosphorus, and 1% significantly rose that of alkali hydrolysis nitrogen.

  Conclusion  As commonly known, presence of biochar can improve the structure, fertility, and microbial activity in soil. In this study, it was found that an addition of the soil conditioner at 1% level achieved not only the desirable effects on the soil but also on the growth of continuous monocropped cucumber plants.