Effect of Pistachio Shell Biochar and Organic Cow Manure Application on Plant Growth, Water Retention Capacity and Nutrient Stress Mitigation

Abstract Sustainable crop production supports food security by mitigating water and nutrient stress from manures by excessively drained water. Cow manure is a good nutrient resource to enhance soil fertility and plant growth but requires a suitable amender to reduce the nutrients loss by leaching. Worldwide more than 20,400 metric tonnes of pistachios were consumed where roughly 30% of the weight of the nut is the shell which could be a good feedstock for biochar production. Therefore, this study was conducted to produce biochar from pistachio shell by pyrolysis process at three different temperatures 350 to 550 °C and based on various properties characterization, the biochar at 450 °C was amended with 0% (control), 2%, 4% and 8% to the cow manure for eggplant growth ( Solanum melongena ). Out of all fractions of biochar application, 2% biochar has virtuous performance to increase 5.63 ± 1.45 cm of plant height, 1.33 ± 4.79 cm leaf length and 1.90 ± 4.43 cm leaf width over the control. The leaf chlorophyl content and plant biomass were also significantly ( p = 0.02) increased compared to the control. The lower fraction of biochar application showed almost similar water retention capacity with control ( p > 0.11) due to the better plant growth. Based on the findings of this study, it is proposed that lower fraction of biochar application with manure is a constructive solution to improve soil quality, reduce nutrient loss and eggplant growth. Under the circular economy and frameworks of sustainability, pistachio shell biochar production has a high legislative attention on valorizing nutshell wastes. Graphical Abstract