Effect of Biochar and Chemical Fertilizers on Some Soil Properties, Yield and Quality Characteristics of Black Seed (Nigella sativa) under Water Deficit

A field experiment was conducted which focused on the effects of walnut wood biochar and chemical fertilizers on quality characteristics of Black Seed (Nigella sativa) under water deficit conditions. The experiment was carried out in a split plots factorial layout based on a randomized complete block design with three factors and three replications. Three levels of irrigation (I1: 100%, I2: 70% and I3: 40% of crop water requirement) were assigned as the main plots and the combination of three levels of biochar (B1: 0, B2: 10 and B3: 20 t.ha-1) and two levels of chemical fertilizers (F1: without and F2: with chemical fertilizer) were allocated to sub plots. Recommended dose for nitrogen, phosphorus, and potassium was 150 kg N.ha-1, 75 kg P2O5.ha-1 and 100 kg K2SO4.ha-1, respectively. Results showed that irrigation had no effect on soil properties, but application of 20 t ha-1 of biochar improved soil saturation percentage, soil organic carbon, and total nitrogen. Irrigation significantly influenced the seed yield, oil yield, oil percentage, and fatty acids, except oleic acid. The 70% water requirement treatment increased the amount of fatty acids, except stearic acid. Plant quality characteristics significantly increased by 10 t ha-1 biochar application. Application of 10 t ha-1 biochar plus 70% irrigation water requirement and using chemical fertilizer (I2B2F2) produced the highest seed yield (1158.4 kg ha-1). Based on the results, it seems that application of 10 t ha-1 biochar is suitable for black seed production under water deficit condition.