ROOT PHYTOMASS RECOVERY AND ROOTING CHARACTERISTICS OF FIVE AGROFORESTRY TREE SPECIES IN EASTERN INDIA

Knowledge of the quantitative assessment and structural development of root system is essential to improve and optimize the productivity under agroforestry systems. We conducted studies on root phytomass recovery by sieves of different mesh sizes (2.0, 1.0, 0.5 and 0.25 mm) and root distribution for five, four-year-old agroforestry tree species, namely, Acacia auriculiformis, Azadirachta indica, Bauhinia variegata, Bombax ceiba and Wendalendia exserta. Results indicated that the 0.5-mm sieve was adequate for recovery for the majority of roots. Maximum rooting depth was recorded in W. exserta (2.10 m) and minimum, in B. variegata (1.00 m). Variation in horizontal root spread was 2.05 m in B. ceiba and 8.05 m in A. auriculiformis. Root spread exceeded the crown cover for all tree species. The first order lateral roots were more horizontal than the second order. The length and diameter of the main root were highest in A. indica (108.3 cm) and B. ceiba (23.2 cm) respectively. Maximum length of lateral roots was recorded in B. variegata (201.6 cm) and maximum diameter, in A. indica (1.8 cm). Total root phytomass among different species accounted for 18−38% of the total tree biomass. This study infers that although all trees have potential to conserve water and improve fertility status of the soil, A. auriculiformis is the most effective for promoting soil fertility. The deep rooted W. exserta and A. auriculiformis will be preferred for cultivation under agroforestry systems and could reduce competition for nutrients and water by pumping from deeper layers of soil.