SHORT COMMUNICATION BIOMASS PRODUCTION AND SOIL AMELIORATION IN A HIGH DENSITY TERMINALIA ARJUNA PLANTATION ON SODIC SOILS R. K. JAIN* and BAJRANG SINGH National Botanical Research Institute, Lucknow (U.P.) Ð 226 001, India (Received 10 May 1997; revised 20 November 1997; accepted 22 November 1997) AbstractÐThree plant densities of Terminalia arjuna (10 000, 20 000 and 30 000 plants ha À1 ) established on a sodic wasteland, were evaluated for their biomass production potential, energy content and soil amelioration at Lucknow, India (80853' E; 26845' N). Height, diameter and biomass production increased signi®cantly (P < 0.05) from lower to higher plant density. The yearly growth and biomass accumulation also increased signi®cantly upto six years. The highest density plantation accumulated 516 GJ ha À1 energy content at six years. The impact of the plant density on soil properties showed a signi®cant reduction in soil bulk density, whereas the porosity and water holding capacity of the soil increased at the highest density. Soil pH, exchangeable sodium percentage and exchangeable Na + were reduced with the plant age and plant density whereas organic C, K + , Ca ++ and Mg ++ cations increased with plant growth as well as plant density. # 1998 Published by Elsevier Science Ltd. All rights reserved KeywordsÐPlant density; Terminalia arjuna; sodic soil amelioration; biomass; energy. 1. INTRODUCTION In order to alleviate the fuelwood problem in India short rotation intensive culture (SRIC) of trees on degraded lands appears to be a viable option. 1,2 Consequently various energy plantation programmes have been initiated during the last decade. 3,4 Of these, plantations established on sodic lands have received con- siderable attention. 5,6 Terminalia arjuna has been observed to be a promising species on sodic soils as it survives well even in water- logged areas which is a common feature of such sites. 7,8 This study was carried out in a short rotation, high density plantation of T. arjuna to evaluate the production potential and bioenergy content. The eects of tree growth on soil amelioration were also moni- tored over a 6-year period. 2. MATERIAL AND METHODS 2.1. Experimental site Plantations were established at Lucknow in north India (80845' ±53' E to 26840' ±45' N). The general relief of the site is ¯at with a gentle slope of about 1±1.5%. Site soils are inceptisol with a silty clay loam texture and are characterized by high pH (9.3±10.8) and very low organic matter. These soils are sodic with exchangeable sodium percentage (ESP) varying from 30 to 50 and electrical conductivity < 0.6 dS m À1 . Carbonate and bi- carbonate of Na + and Ca ++ are dominant ions. The soil pro®le has no conspicuous hor- izons but shows mottling of MnO 2 and round- ish granules of iron varying 3±5 mm in size. Indurated pans comprised of large lime nodules (CaCo 3 ) ranging from 10 to 31 mm are found at 45±75 cm depth of the soil pro®le which restricts the subsurface drainage and root development. The water table ¯uctuates between 4 and 5 m depth. These soils often get water-logged during rains and impede root respiration. One-year-old seedlings of Terminalia arjuna Bedd. were planted in re®lled soil pits, 0.5 m 3 in size. Planting stock was procured from Allen forest nursery, Kanpur. Experimental plots measuring 10 Â 5 m had 50, 100 and 150 trees per plot spaced at 1 Â 1 m, 1 Â 0.5 m and 0.66 Â 0.5 m with a density of 10 000, 20 000 Biomass and Bioenergy Vol. 15, No. 2, pp. 187±192, 1998 # 1998 Published by Elsevier Science Ltd. All rights reserved Printed in Great Britain 0961-9534/98 $19.00 + 0.00 PII: S0961-9534(98)00011-7 *Author to whom all correspondence should be addressed. 187