ORGANIC CARBON AND NUTRIENT BUILD-UP IN A CALCIORTHENT SOIL UNDER SIX FOREST TREE SPECIES

ABSTRACT

The study was conducted under 18-year-old forest tree plantations consisting of six multipurpose tree species;

	• [Pongamia pinnata (Linn.) Pierre,
	• Albizia procera (Roxb.) Benth.,
	• Acacia lenticularis (L.) Willd,
	• Eucalyptus tereticornis (Smith),
	• Swietenia mahagoni Linn, and
	• Terminalia arjuna Bedd.]

at the experimental area of the Department of Forestry, Rajendra Agricultural University, Bihar, Pusa (Samastipur), India.

The aim was to identify tree species that could grow and ameliorate calciorthent soils deficient in soil organic carbon (SOC), available N and P₂0₅, and available Zn and Fe. Most of the tree species studied were effective in bringing about improvement in the soil properties as reflected by the significant increases in EC, SOC, available macro-nutrients (N, P₂O₅, and K₂O) and microutrients. Of these tree species, E. tereticornis showed maximum SOC (7.54 g kg⁻¹) but with A. procera, T. arjuna and A. lenticularis lower but not significantly so. Higher available macronutrients were recorded under the leguminous tree species i.e. A. procera and A. lenticularis followed by P. pinnata. The order of the levels of the micronutrients in the different species varied but with E. tereticornis. T. arjuna, and P. pinnata usually among the highest. E. tereticornis, A. procera and T. arjuna all produced high litter fall (over 8 Mg ha⁻¹). A. procera produce most timber, followed by T. arjuna. Considering timber production, carbon sequestration and improvement in soil fertility, A. procera was found to be the best among the tested tree species, and may be a viable option for natural resource management using an agroforestry system to sustain long-term soil productivity in calcareous recent alluvial soils of Bihar.

Key words:

• bio-amelioration
• available nutrients
• organic carbon