On the performance of poplars (Populus deltoides) on marginal soils in northern India

Transcription

1 PERGAMON Biomass and Bioenergy 16 (1999) 257±262 On the performance of poplars (Populus deltoides) on marginal soils in northern India P.N. Misra, S.K. Tewari * National Botanical Research Institute, Lucknow± , India Accepted 3 August 1998 Abstract Attempts to raise poplar plantation were successfully made on partially reclaimed sodic lands of northern India. The silvicultural practices for poplar plantation on marginal soils beyond its established geographical limits were investigated between 1985 and The investigations included trials for evaluation of suitable clones, optimum spacing, irrigation and fertilizer requirement and inter-cropping studies. The performance of indigenous poplar clones was better than exotic clones. The spacing of 5 4 m (wider in North±South) produced the highest volume. Irrigation was very critical in summer months and 12±14 irrigations per year were required for good growth of trees. Poplars responded to application of nitrogen (160 kg ha 1 ) and phosphorus (100 kg ha 1 ) fertilizers. Intercropping with German chamomile resulted in maximum net return and wheat produced the highest increment in poplar diameter. # 1999 Elsevier Science Ltd. All rights reserved. Keywords: Poplar; Clone evaluation; Fertilization; Spacing; Irrigation; Intercropping 1. Introduction Poplars have only a limited zone in India. Outstanding success has been obtained in tarai region of Uttar Pradesh, which lies between latitude of 298 and 308N. Besides its adaptation to certain geographical limits, the poplars prefer good aerated soils. However, there are reports that it can grow on alkaline [1] to moderately acidic soils while extremely acidic soils are harmful to it [2]. Badly structured compact soils with poor porosity do not suit its cultivation [3]. Its * Corresponding author. successful cultivation on saline±sodic soils in Hissar (28±298N latitude) has also been reported [4]. Having a shallow root system, its cultivation is likely to succeed on such sites which have indurated (clay and or kankar) pan at varying depth (0.75 to 1.0 m) in the subsoil. Being a deciduous tree, the poplar sheds large quantities of leaves during winter months. These leaves add organic matter to soil which tends to improve it. The crown structure of poplar trees is such that they form a thick canopy during their active growth period, which coincides with summer months, providing enough shade to restrict the upward movement of subsoil water and thereby accumulation of salts at the surface /98/$ - see front matter # 1999 Elsevier Science Ltd. All rights reserved. PII: S (98)00066-X

2 258 P.N. Misra, S.K. Tewari / Biomass and Bioenergy 16 (1999) 257±262 These growth characters of the poplar formed the basis of the idea of its cultivation in sodic land, which is considered un t and lies outside the acclimatized zone. The results of several trials, conducted to standardize its cultivation technique in such conditions, are summarized in the following text. 2. Materials and methods 2.1. The Geo-edaphic description The experiments were conducted at Banthra Research Station and its Aurawan Centre during the period 1985±1995. The site is located at to E longitude and to N latitude, at an elevation of 129 m above mean sea level. The area falls into a sub-tropical zone. The ph and electrical conductivity of the soil in di erent plots ranged between 8.5 and 9.0 and 0.4±1.0 ds m 1, respectively. The texture of the soil was silty clay loam. The soil was poor in organic matter (0.2±0.3%) and total nitrogen (0.018±0.021%), medium in available phosphorus (7±9 kg ha 1 ) and rich in available potassium (330±350 kg ha 1 ) The planting material and technique The cuttings were planted in the nursery beds at cm spacing in January±February. After one year, the entire transplants (ETPs) were planted in the experimental elds in pits of 1m 1m 1 m dimension, lled with 1:1:1 mixture of top soil, sand and well decomposed FYM in January±February. Frequent, adequate and timely irrigations were applied in the plantation, particularly during summers. Chemical fertilizers were not applied (except in the fertilizer trial) and pruning operations were done as per standard schedule. At the age of 3±4 years, serious infestation of leaf defoliators (Pygaera fulgurita) was encountered in the month of September, which was e ectively controlled by Endosulfan spray at 0.05% a.i. concentration The details of experimental sets Clone evaluation trials The trial with three rst available poplar clones G-3, G-48 and D-121 started in 1985 with 64 observation plants of each clone. Observations on their growth performance were recorded in the month of January every year. In the following years, more clones were collected and planted in the germ plasm collection, `Populatum' between 1988 and In 1990, these clones were put in di erent sets of evaluation trials. The cuttings were planted at 1 m 1 m spacing, directly in the eld which were spaced out at 3m 3 m in the following year. Number of observation trees varied between 15 and 20 depending upon mortality of plants Spacing trial The trial with di erent combinations of 3, 4, 5 and 6 metres inter- and intra-row spacings was initiated in 1986 using Nelder's design (clone D- 121). Observations on dbh and top height were recorded in January every year and volume was calculated using the equation given by Chaturvedi [5] (V = D 2 H) Irrigation trials The experiment was laid out in randomized block design with four replications at two sites (Aurawan and Banthra) in February, The number of irrigations varied between six and 14 during the rst two years. Later on, from January 1992 the number was reduced to 5±12 irrigations per year. ETPs of clone G-3 were planted at 4 m 4 m spacing in 16 m 16 m size beds Fertilizer trial The fertilizer trial was conducted in plots of 12 m 12 m size, accommodating nine plants/bed at 4 m 4 m spacing. Three levels of nitrogen (N) and phosphorus (P) were arranged in strip plot design with four replications. Cuttings of clone G-3 were planted in January, Nitrogen was applied as urea at 0, 80 and 160 kg ha 1 in three splits of 3:3:2 during the active growth period in the months of June, July and

3 P.N. Misra, S.K. Tewari / Biomass and Bioenergy 16 (1999) 257± Fig. 1. Volume of poplar trees under square and rectangular planting at nine years of age.

4 260 P.N. Misra, S.K. Tewari / Biomass and Bioenergy 16 (1999) 257±262 August. Phosphorus was applied in the form of single super phosphate at 0, 50 and 100 kg ha 1 as basal application with the rst dose of N Intercropping trial Poplar clone G-3 was inter-cropped with 3 legumes (peas, lentil and Egyptian clover) and 3 non-legumes (wheat, mustard and German chamomile [Chamomilla recutita]). The performance of agricultural crops was evaluated vis-aá -vis the growth of poplars during the rst three years (1989±90 to 1991±92). The poplars were planted at 5 m 5 m spacing in January, The crops were sown during the winter cropping season in four beds of 20 m 20 m size, accommodating 16 poplars in each bed. The interim net income from cultivation of the inter-crops was computed on the basis of prices prevailing at that time. 3. Results and discussion 3.1. Clone evaluation trials The survival of clones G-3, G-48 and D-121 was very poor in the rst year as the planting was delayed by about a month. Clone G-3 took the lead in growth from the rst year and attained 13.1 cm dbh and m height at nine years of age, followed by G-48 and D-121. To avail a wider base for selection of suitable clones for the marginal soils, a collection of clones of di erent origin was maintained. These clones were put in various sets of clone evaluation trials. Among six promising clones tested at Aurawan Centre, indigenous clone L-30/82 recorded the maximum diameter (10.02 cm), while clone of American origin S7C15 recorded the maximum height (12.13 m) at four years of age. Among 21 other clones, evaluated in di erent sets of trials, L-13/82, L-30/82, L-34/82, L- 49/82, L-52/82 and S7C1 attained more than 10 cm dbh and approximately 11 m or more top height at ve years of age. Except S7C1 (American) clone, all other superior performing clones are indigenous, suggesting thereby better performance of indigenous clones on partially reclaimed alkaline lands having developed adaptability to Indian conditions. Superior performance of indigenous and/or American clones in Tarai region of Uttar Pradesh has been reported [6] Spacing trial The trees planted at the widest spacing of 6m 6 m produced maximum volume per tree but because of fewer plants per unit area, the total volume per ha was less than closer spacings. At nine years of age, 20 m 2 spacing resulted in the highest volume of m 3 ha 1 in the North±South wider spacings and m 3 ha 1 in the East±West wider spacings (Fig. 1). This spacing also permits intercropping agricultural crops with poplars. Jha, Srivastava, Verma and Prasad [6] have reported that for larger rotation (10 years) block planting, the optimal spacing is 5m 3 m in Tarai region while closer spacing could be adopted for short rotations [1, 3]. The performance of rectangular spacings lengthwise facing North±South rather than East±West, is better than that of square spacing [6]. The closest spacing (9 m 2 ) resulted in poor diameter growth of poplars and although the larger number of plants/unit area resulted in the calculated value of wood volume/ha being higher than that for widely spaced trees, because the trees are too thin, they are of low mercantile value. The improvement in dbh with increase in spacing or reduction in stand density is well documented in literature [12, 13] Irrigation trial For raising a poplar plantation successfully, an adequate supply of irrigation water should be made available at least during the rst two seasons, during the hot weather from immediately after transplanting in February up to the end of June [7]. Application of six irrigations per year (one each in February, March, April, May, June and October) resulted in very poor survival of plants (30±35%) as against more than 90% with 14 irrigations per year during the rst year. The number of irrigations were reduced from the second year which caused a serious set-back to the

5 P.N. Misra, S.K. Tewari / Biomass and Bioenergy 16 (1999) 257± Fig. 2. Mean annual increment in diameter of poplar trees and net returns from intercropping di erent agricultural crops. plants in the treatments getting ve and six irrigations per year. Irrigation was more crucial in April, May and June and where water stress occurred during these months, the leaves wilted, turned yellow and fell, the plant ceased to develop and ultimately died when exposed to further stress. The stress was more severe in Banthra because of poor physical properties of the soil. The increment in diameter and height was maximum in trees getting 12±14 irrigations per year. The `F' test showed that the di erences

6 262 P.N. Misra, S.K. Tewari / Biomass and Bioenergy 16 (1999) 257±262 between irrigation frequencies were signi cant for dbh in all the years and for top height in the second and third year only. Between 1992 and 1995, the annual diameter increment was 5.50 cm, 3.07 cm, 1.89 cm and 1.15 cm under the maximum water supply against 2.51 cm, 2.30 cm, 0.23 cm and 0.72 cm under the lowest water supply. The di erence of diameter growth between these two treatments was highly signi cant. The MAI in volume ranged between 3.02 to 4.84 m 3 ha 1 under the lowest water supply (5±6 irrigations per year) against 4.72±16.58 m 3 ha 1 under the highest water supply (12±14 irrigations per year) during 1991±95. Szekai, Fengjne and Daoqun [8] found that the economic bene t, based on the cost accounting of irrigation was signi cant in young poplar plantations Fertilizer trial Though N application increased the diameter and height of poplars, the di erences were statistically non-signi cant. Phosphorus application resulted in signi cant increase in its growth. The application of phosphorus at 50 and 100 kg ha 1 produced 35.6 and 66.8% more volume than control at three years age. The interaction e ect of N and P fertilizers was non-signi cant though the highest dbh (13.83 cm) and top height (10.18 m) were recorded with applications of 160 kg N and 100 kg P per hectare Intercropping trial The mean annual increment in diameter of poplars (clone G-3) and net returns obtained by intercropping poplars with di erent agricultural crops during winter season are depicted in Fig. 2. The maximum increment in poplar diameter was recorded in beds inter-cultivated with wheat, followed by chamomile, Egyptian clover, mustard, pea and lentil. The crops performing better (wheat, chamomile and E. clover) were supplied with 5±8 irrigations in the cropping season and were more nutrient and management demanding than mustard, pea and lentil, which were supplied with only two irrigations. As such there was no signi cant di erence in poplar growth, inter-cultivated either with legumes or nonlegumes. After three years of inter-cultivation, poplars attained diameter and top height of 10.07± cm and 9.16±11.81 m, respectively, which was much better than the growth of the same clone in other trials. In terms of extra-monitory bene ts from inter-cultivation of agricultural crops, chamomile followed by wheat gave maximum net returns in all the cropping seasons. Acknowledgements The authors are thankful to Dr P.V. Sane, ex- Director, National Botanical Research Institute, Lucknow for providing necessary facilities and guidance during the course of investigations. Thanks are also due to Dr R.S. Katiyar, Farm Manager, for the help rendered by him in maintaining the experimental plantations. The nancial grant provided by the Department of Nonconventional Energy Sources, New Delhi for initiating the investigations is duly acknowledged. References [1] Chaturvedi AN. Poplars for farm forestry in Uttar Pradesh. Indian For 1983;109:661±4. [2] Chandra JP. PoplarÐa cash crop for North Indian farmers. Indian For 1986;112:698±709. [3] FAO Forestry Series No. 10. Poplars and Willows in wood production and land use. International Book Distributors, Dehradun, [4] Srivastava MB, Tewari KN, Srivastava M. A orestation on salt a ected soils in India. Indian J For 1988;11:1±12. [5] Chaturvedi AN. Volume table of Populus deltoides clones G-3, G-48 and IC. 49. U.P. Forest Bulletin, [6] Jha KK, Srivastava PC, Verma RS, Prasad D. Choice of spacing poplars in Tarai. Indian J For 1991;14:163±8. [7] Chaturvedi AN. Poplar farming in U.P. (India). 45. U.P. Forest Bulletin, [8] Szekai Z, Fengjne L, Daoqun Z. E ect of water supply on volume increment in young poplar plantations. In: Proceedings of IUFRO XVIIIth World Congress, Ljubljana (Yugoslavia), 1986.