Introduction: Although the use of fertilizer in poor soils is necessary to increase soil fertility and optimal plant growth, in recent years, the use of chemical fertilizers has caused a lot of environmental damage. Currently, one of the well-known ways to minimize the use of chemical fertilizers is the use of resources and soil modifier compounds, including biochar. Biochar is a carbon-rich material that has recently shown promising results for the sustainable management of agro-ecosystems, increased plant growth, and soil health. Biochar enhances the capacity for water retention and nutrient absorption, ensuring timely delivery to the plant.
Material and Methods: This study was conducted at Ilam University's research greenhouse from 2022 to 2023. The experiment followed a factorial design and utilized a completely randomized approach with three replications. The treatments consisted of three different barley cultivars (HOR8887, HOR7496, and HOR9793) and three levels of biochar (control or zero, 2 g/kg, and 4 g/kg). To create the biochar, natural asphalt was used, which is a readily available and cost-effective material commonly found in underground mines. It is characterized by its hard, black composition and high melting temperature. The process of synthesizing the chemical biochar involved sulfonating Iranian natural asphalt with concentrated sulfuric acid, resulting in the formation of potassium natural asphalt sulfonate (K-NAS). Initially, one gram of Iranian natural asphalt was mixed with 5 ml of concentrated sulfuric acid and stirred at room temperature for 15 minutes. The reaction mixture was then heated for two hours at 220 degrees Celsius and gradually added to water and ice. The resulting product, natural asphalt sulfonic acid (NASA), was washed twice with distilled water and dried at 100℃. Subsequently, one gram of NASA was mixed with 20 ml of 10% potassium hydroxide solution and stirred for one hour at room temperature. The solvent was evaporated, and the mixture was dried at 100 degrees Celsius to obtain potassium natural asphalt sulfonate (K-NAS), also known as chemical biochar.
Results and Discussion: The results of this experiment showed that there was a significant difference between the barley cultivars for the number of fertile tillers, flag leaf length, spike length, plant height, peduncle length, and hundred seed weight at the probability level of 1%. Biochar had a positive and significant effect on flag leaf length, spike length, awn length, number of seeds per spike, and hundred seed weight at the probability level of 5%; But it showed a non-significant effect on other functional traits. But it showed a non-significant effect on other functional traits. The results showed that the highest number of claws per plant was related to the HOR9793 variety with a level of 4 gr of biochar and an average of 14.8. In cultivar HOR7496, the highest number of seeds per spike 23.4, was obtained with the consumption of 4 gr/kg of biochar. The highest weight of 100 seeds, corresponding to the variety HOR8887, was obtained at the rate of 4.34 grams when consuming 4 gr/kg of biochar.
Conclusion: Our experiment's overall findings indicate that utilizing 4 g/kg of this biochar can significantly impact both the yield and its components in greenhouse conditions. Consequently, considering the plentiful availability and cost-effectiveness of this particular biochar, we strongly recommend conducting further field studies.