Effect of Wheat-Derived Biochar on Soil Nutrients Availability and Nutrients Uptake by Two Safflower (Carthamus tinctorius L.) Cultivars under Water Stress

Biochar may improve the negative effects of water stress on plant dry weight and nutrients uptake of Safflower (Carthamus tinctorius L.). The effects of 1.5 and 3% biochar application to a calcareous soil cultivated with two cultivars of safflower under normal and 50% of normal irrigation on soil nutrients availability, plant dry weight, and nutrients concentration were studied. Results indicated that the biochar application increased soil electrical conductivity (from 0.52 to 1.46 dS m(-1)) and the availability of the soil phosphorus (from 8.0 to 13.2 mg kg(-1)), potassium (from 185 to 1107 mg kg(-1)), iron (from 0.76 to 1.40 mg kg(-1)) and manganese (from 1.10 to 4.57 mg kg(-1)). Water stress and plant cultivar treatments had no effect on the soil nutrients availability. The dry weight of Goldasht and Esfahan cultivars was 1.89 and 1.73 g pot(-1), respectively, and decreased 12 and 26% with 1.5 and 3% biochar application, respectively. The decreases in the plant dry weight with water stress in soils treated with 0, 1.5, and 3% biochar were 34, 27, and 18%, respectively. The plant concentration of phosphorus, potassium, iron, and manganese was increased with biochar application and was associated with soil nutrients availability.