Distribution of Different forms of Aluminium (Al) under Tea Plantations of Different Age in Eastern Bihar of India

On average, aluminium makes up 7–8% of the earth's crust, making it the most prevalent metal on the planet and the third most abundant element (after silicon and oxygen). Al is present and widespread throughout the plant life cycle, although it serves no particular biological purpose. Al is mostly present in soil as minerals (aluminosilicates and aluminium oxides) therefore, organisms are typically not exposed to significant quantities of it. The paper aims to distribute different forms of aluminium (Al) under different age tea plantation plantations in Eastern Bihar of India. The study was carried out in different age tea plantations in the eastern region of India with the objective to find out the different forms of Al in the plantation. A representative soil sample was taken from each of the three (3) tea plantations that were taken into consideration for each treatment. Free oxides of iron and aluminium were extracted using the citrate-dithionite-bicarbonate (CBD) method. Following the tea plantation age, treatments were taken into consideration, viz. (i) T1: < 10 years old, (ii) T2: 10–20 years old, (iii) 20–30 years old, (iv) 30–40 years old, and (v) > 40 years old tea gardens. Results found that all forms of Al, such as exchangeable Al, Extractable Al, Non-exchangeable Al, Oxide form of Al/CBD extractable-Al, and Amorphous Al/Oxalate extractable Al concentration, increased with increasing the age of the tea plantation. Furthermore, all forms of Al showed significant and positive correlation with each other. Concentration of various forms of Al in tea soils followed in the order of Oxalate-Al > CBD-Al > Exchangeable Al > Extractable Al > Non-exchangeable Al. Forms of Al concentration gradually increase during tea cultivation over the years, which must be the cause of lowering soil acidity and affect nutrient availability to tea plant growth at old age plantations. Clay content of these soils varied from 19.75 to 21.83%, with a mean content of 20.94%. Water holding capacity found to be low due to light-textured soil, having ranged between 27.00 and 35.67% with an average of 30.76%. All soils were found to be moderately acidic, with soil pH ranging between 4.65 and 5.48, with an average of 5.01. From this study, it may be concluded that the content of all fractions of aluminium concentration increases with increasing age of the tea plantation and all exists exist in equilibrium condition conditions in the soil solution.