Effect of Date Kernel Biochars on Enzymatic Activity in Rhizosphere and Non-rhizosphere Soils of European Borage (Borago officinalis L.)

Abstract

The aim of this study was to investigate the effect of date kernel biochar and nano-biochar on enzymatic activities of rhizosphere and non-rhizosphere environment of European borage. The date kernel was converted to biochar at 400 and 800 ºC pyrolysis temperatures and mixed with different soils. Four soils with different characteristics including acidic, calcareous, saline-sodic and saline-highly sodic were selected. Biochars were then converted to nano-size materials using the rolling ball method. Also nanoparticles were extracted from date kernel powder by hydrothermal method. The obtained biochars were mixed with soil and transferred to greenhouse pots. European borage was planted and harvested after 60 days. Rhizospheric and non-rhizospheric soils were collected and the activity of acidic and alkaline-phosphomonoesterase, protease and β-glucosidase enzymes were measured. The highest and lowest activities of acid-phosphomonoesterase, protease and β-glucosidase enzymes were found in the acidic and saline-highly sodic soils, respectively. However, the highest alkaline-phosphomonoesterase activity was observed in the saline-highly sodic soil. The activity of enzymes in the rhizosphere soil was greater than in the non-rhizosphere soil. The highest activities of enzymes were found in the control and were reduced by using biochar, nano-biochar and nanoparticle biochars. The conversion of biochar to nano-biochar could not increase the activity of enzymes in the soil.