J OURNAL OF FOREST PRODUCTS & INDUSTRIES, 2013, 2(2), 40-44 ISSN:2325–4513(PRINT) ISSN 2325 - 453X (ONLINE )
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Impact of Irrigation with Sewage Effluent on the Growth and Wood Properties of Two Forest Tree Seedlings Fatma A. Hassan1 and Hayssam M. Ali*1, 2 1
Department of Timber Trees Research, Horticulture Research Institute, Agriculture Research Center, Alexandria, Egypt (fatmahassan4@hotmail.com) 2 * Department of Botany and Microbiology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia (hayssam77@hotmail.com) (Received: February 05, 2013; Accepted: February 21, 2013)
Abstract— Two sources of wastewater from the Eastern and Western treatment plant of Alexandria city were used for irrigation of Acacia saligna and Leucaena leucocephala seedlings either directly (100%) or mixed with tap water (50% v/v) in addition to using tap water only as the control. Irrigation with 100% concentration of wastewater from the Eastern sewage treatment station at 100% concentration decreased the growth of Acacia saligna seedlings. Sewage effluent had increased specific gravity in all the treatments except with low concentration from the Eastern source; Fiber length was increased when the seedlings were irrigated with wastewater from the eastern sewage treatment station at 100% concentration. The growth of Leucaena leucocephala seedlings decreased when irrigated with wastewater, the decrease was more pronounced with wastewater from the eastern sewage treatment station at 50% concentration. Wastewater did not affect specific gravity of Leucaena leucocephala seedlings; however wastewater from the Western sewage treatment plant at 50% concentration increased fiber length of those seedlings. Index Terms— Sewage effluent, Acacia saligna, Leucaena leucocephala, Growth rate, Specific gravity, Fiber length.
I. INTRODUCTION
W
ater consumption in dry-land regions is likely more critical than in more temperate and humid regions as a result of low perception and high summer temperatures, continued degradation of land and water resources by human activities etc. Many efforts are taken worldwide to furnish fresh water to meet the ever-growing demand of agriculture and urban sectors. Reuse of wastewater as one of such efforts, has been practiced in many countries for agricultural irrigation. Based on the water quality, certain crops such as fibers, forage, cereal and timber trees can be selected with the necessary
*Corresponding author.
precautions to produce crops with least contamination possible [1]. Forest trees may be more tolerant than many other plants to irrigation with wastewater. Cultivating green belts of forest species around cities under wastewater irrigation helps to make ecological balance and improves environmental quality by self-treatment of wastewater through land application and forest irrigation [2]. However, the ability of trees to survive and grow under conditions of wastewater irrigation seems to be variable among species. because wastewater usually contains undesirable constituents as salts, trace elements, organic compounds, pathogens etc. Acacia saligna (Labill.) is a hardy, highly adaptable, fast growing, nitrogen-fixing shrub or small tree. It is a relatively short-lived species that tolerates a wide range of soils (acid and alkaline) and is moderately salt tolerant [3]. Despite a preference for natural populations to grow on water-gaining sites, it has been successfully cultivated on wide range of recharge sites in areas that receive as low as 200 mm of annual rainfall [4]. It has been used to remediate degraded sites, including excessively sandy areas and mine sites [4]. The foliage has been used as a source of stock fodder, its wood is suitable for wood composite products and its seeds have potential as a source of food [3], [4], [5], [6]. The bark yields of A. saligna about 30% tannin. The growth performance of this species is currently being assessed by the Flora Search project [5]. A disadvantage of this species is that it has become a weed in numerous areas where it has been grown [3]-[7]. Leucaena leucocephala (Lam.) makes excellent charcoal with a heating value of 29 MJ/kg and good recovery values (25-30%). Fuel oil for diesel engines was found no harmful agents in the ash [7]. Fiber values are similar to those of other tropical hardwoods, and it produces paper with good printability but with low tearing and folding strengths. The wood-pulp strength is greater than that of most hardwoods, with almost 50% greater ring crush [8]. Its pulping properties are suitable for both paper and rayon production. Timber from this tree has hard heavy wood (about 800 kg/m2), with a pale yellow sapwood and light
J OURNAL OF FOREST PRODUCTS & INDUSTRIES, 2013, 2(2), 40-44 ISSN:2325–4513(PRINT) ISSN 2325 - 453X (ONLINE ) 41 reddish-brown heartwood. This wood is also used for particleboard production, the wood is known to be of heavy wood and to dry without splitting or checking [8] - [9].
4-2. Stem diameter (mm) The diameter (out bark) of the seedlings was recorded at 5 cm above the ground by using a caliper to the nearest 1 mm.
The present study was undertaken to determine the effects of irrigation with treated sewage effluent on growth and wood properties of Acacia saligna and Leucaena leucocephala seedlings.
5- Harvesting and sampling: From each treatment four seedlings were randomly selected then the plants were removed and transplanted to the laboratory. Four sticks of 2 cm long each were cut from each plant, for specific gravity (SG) determination, and 5 cm long piece of wood from the middle of each seedling stem was used for fiber length (FL) measurements.
II. MATERIALS AND METHODS This study was carried out at the nursery of Timber Trees Research Department of Sabahia, Horticultural Research Station at Alexandria, Egypt. To investigate the effects of irrigation with different sources of sewage effluent on growth, specific gravity and fiber length of Acacia saligna and Leucaena leucocephala. 1- Plant material Seedlings of one year old Acacia saligna and Leucaena leucocephala were planted in 30 cm diameter pots filled with about four kilograms of sandy loam soils. Two source of sewage effluent from both the eastern and the western sewage treatment stations of Alexandria City was used for irrigation the seedlings. Seedlings were irrigated to field capacity at rate of 200 ml per pot weekly. 2- Treatments Five irrigation treatments were used either directly (100%) or after mixed with tap water (50%, v/v). 1- Control irrigation with tap water only. 2- E1 irrigation with wastewater from the Eastern sewage treatment plant only. 3- E2 irrigation with Eastern wastewater blended with tap water (1:1 v/v). 4- W1 irrigation with wastewater from the Western sewage treatment plant only. 5- W2 irrigation with western wastewater blended with tap water (1:1 v/v). 3- Water analysis Water analysis was performed according to the standard methods [10]. Available N was determined by kjeldahl method and available P was determined by the ascorbic acid molybdenum blue method [11]. Heavy metals were analyzed using Atomic Absorption Spectrophotometer (A.A.S) using Perkin Elmer, 3300. The results of the analysis of sewage effluent used in the current study are presented in Table 1. 4- Growth measurements: 4-1. Plant height (cm) For each treatment of the two species, total height of seedlings was measured from ground level to the top of the seedlings using a graduated stake to the nearest 0.5 cm.
5-1.Specific gravity A 2 cm long sample strip that is free from any natural defects was machine cut from the stem bases of each seedling and used in the analysis. Specimens were coded, debarked and aspirated under vacuum until water logged. Then the oven dried weight was obtained and the maximum moisture content was calculated. The specific gravity of each specimen was determined using the following equation developed by [12]. Specific gravity =
________1________ Ws-Wo/ Wo + 1/Gso
Where:Ws = saturated weight of wood specimen, Wo = oven dried weight of wood specimen, and Gso = average density of wood substance (1.53) 5-2. Fiber length (mm) Samples of wood were collected from the stem of each seedling (5 cm from the middle of each seedling stem). Each sample was chipped into chips. These chips were macerated in a mixture of glacial acetic acid and 30% hydrogen peroxide (1:1 v/v) at 60oC for approximately 24 h for delignification, then the material was washed several times by distilled water several times and reduced to fibers by mild shaking. The macerated fiber at each sampled point was stained with 2% safranin pigment and there length was measured to the nearest 0.01 mm by using a projecting microscope. Fifty readings per sample were taken [13]. Statistical Analysis The layout of the experiment was complete randomized design (CRD) was used for the experiment as described by [14]. The five treatments were replicated three times. The means among all used treatments were compared by Duncan’s Multiple Range Test, using SAS procedures [15].
Table (1)
J OURNAL OF FOREST PRODUCTS & INDUSTRIES, 2013, 2(2), 40-44 ISSN:2325–4513(PRINT) ISSN 2325 - 453X (ONLINE ) 42 Chemical characteristics of sewage effluent used in the experiment. Parameter East West pH Ec (ds m-1) TSS (ppm) Na+ Ca++ Mg++ K+ CO3HCO3 ClSO4-Available N (ppm) Available P (ppm) Cd Ni Pb
7.4 3.3 2112 Soluble cations (meq/l) 27.5 2.4 0.58 39 Soluble anions (meq/l) 3.0 12.5 9.5 7.48 1.25 9.00 Heavy metals (ppm) 0.02 0.05 0.29
7.6 3.8 2432 28.5 1.5 0.51 31 16.0 16.8 10.0 5.71 1.08 6.00 0.02 0.06 0.30
III. RESULTS AND DISCUSSION The statistical analysis of the data revealed that the growth of Acacia saligna seedlings increased when they were irrigated with high concentration (100%) of wastewater from the Western treatment plant. The mean values of height and stem diameter of the seedlings in this treatment were significantly higher than those in all other treatments (Table 2). Similar results were obtained by [16] for young saplings of six woody species (conifers and broad leaves) under irrigation with effluent at rate of 50 -200 ml per week. These results are in accordance with those of [17] on Eucalyptus globules, [18] on Ceratonia siliqua, Acacia saligna and Acacia stenophylla, and [19] on Tipuana speciosa.
irrigated with wastewater from the Eastern treatment station, at high concentration (E1) had longer fibers. Using wastewater for irrigating Leucaena leucocephala seedlings resulted in decreasing their growth. The decrease in both height and stem diameter was more pronounced with wastewater irrigation from the Eastern treatment station at low concentrations (Table 3). This finding is consistent with the data presented by [29] for the same species.
Specific gravity of A. saligna showed a slight response under irrigation with wastewater [20], [21], [22], [23]. These results were in agreement with those obtained by [24] on Taxodium distichum and [25] on Albizia lebbek and Citharexylum spinosum, these tree species showed a slight increase in specific gravity and fiber length of wood due to sewage effluent irrigation.
Fiber length of Leucaena leucocephala seedlings increased when they were irrigated with wastewater from the Western treatment plant mixed with tap water (W2) in comparison with those irrigated with the other wastewater treatments (i.e. E1, E2 and W1). Similar results were obtained by [30]. No significant difference were found between fiber length of seedlings which were irrigated with wastewater from the Eastern treatment station (E1, E2) as well as the high concentration from Western treatment plant (W1). Specific gravity of Leucaena leucocephala seedlings were not affected by wastewater irrigation [31].
Irrigation with wastewater from the Western treatment plant at high (W1) or low (W2) concentration decreased fiber lengths of A. saligna markedly compared to those in either E1 and E2 or tap water only. Similar results had been obtained by [26, 27] and [28]. The absence of specific nutrients from the irrigation water creates an imbalance which alters the developing wood substance [21]. Seedlings which were
The consistence of the high values of both height and diameter with longer fibers for L. leucocephala means that accelerating growth of seedlings help to produce superior wood properties for pulp. However, this is not true for A. saligna in the present study. These results are in harmony with those of [32] on Casuarina species, [33] on Albizia lebbek and Tipuana speciosa, and [34] on Melia azedarach.
J OURNAL OF FOREST PRODUCTS & INDUSTRIES, 2013, 2(2), 40-44 ISSN:2325–4513(PRINT) ISSN 2325 - 453X (ONLINE ) 43
Table (2) Effects of sewage effluent irrigation on growth, specific gravity and fiber length of Acacia saligna seedlings. Treatment Height (cm) Diameter (cm) Specific gravity Fiber length (mm) 148.3c 1.25bc 0.44a 0.92b Control 103.7d 1.04c 0.41a 0.94a E1 197.3b 1.57bc 0.36b 0.92b E2 320.5a 2.83a 0.43a 0.89d W1 221.3b 1.79b 0.41a 0.91c W2 Means followed by a similar letter within a column are not significantly different at the 0.05 level probability by Duncan’s Multiple Range Test. Table (3) Effects of sewage effluent irrigation on growth, specific gravity and fiber length of Leucaena leucocephala seedlings. Treatment Height (cm) Diameter (cm) Specific gravity Fiber length (mm) 139.9d 1.15b 0.67a 0.99a Control 217.1b 1.50ab 0.70a 0.94b E1 168.9c 1.36ab 0.65a 0.92b E2 193.7bc 1.37ab 0.66a 0.94b W1 269.3a 1.83a 0.65a 0.99a W2 Means followed by a similar letter within a column are not significantly different at the 0.05 level probability by Duncan’s Multiple Range Test. [7] Tame, T. 1992. Acacias of New South Wales. Kangaroo Press, Sydney.
IV.CONCLUSION Following conclusion can be drawn from this study. 1- The irrigation with sewage effluent solely from the western wastewater had an influence on height and stem diameter for Acacia saligna seedlings. 2- Wastewater did not affect specific gravity of Leucaena leucocephala however, a slight response was found for Acacia saligna. 3- The effect of using wastewater in irrigation depends on tree species. REFERENCES [1] Food and Agriculture Organization of the United Nations (FAO) 1992. Wastewater treatment and use in agriculture. Pescod, M. B. irrigation and Drainage. Paper 47. FAO, Rome. [2] Shende, G.r. and Jr, B. 1982. Wastewater re-use and self-treatment in the promotion of social and recreational forestry. Proceedings of the Semiar on Social Forestry, Nagpur, 20-21 February. [3] Maslin, B.R. McDonald, M.W. 2004. Acacia Search-evaluation of Acacia as a woody crop option for southern Australia. Rural Industries Research Development Corporation Publication No. 03/017, Canberra. [4] Doran, J.C. Turnbull, J.W. (eds.) 1997. Australian Trees and Shrubs: species for land rehabilitation and farm planting in the tropics. Australian Centre for International Agricultural Research, Canberra. [5] Hobbs, T.J, Bennell, M. Huxtable, D. Bartle, J. Neumann, C. George, N. and O'Sullivan, W. 2006. 'Flora Search Agroforestry Species and Regional Industries: Low rainfall farm forestry options for southern Australia.' A report for the Joint Venture Agroforestry Program and CRC for Plant-based Management of Dryland Salinity. RIRDC Publication No 06. [6] Maslin, B.R. Thomson, L.A.J. McDonald, M.W. and Hamilton-Brown, S. 1998. Edible Wattle Seeds of Southern Australia. A review of species for use in semi-arid regions. (CSIRO-CALM: Canberra).
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