Sludge Management: An Exploratory Research Report in Bangladesh
Md. Lokman Hossain
M.S. and B.Sc. in Environmental Science
Institute of Forestry and Environmental Sciences
University of Chittagong
Assistant Programme Officer
Environment and Social Development Organization
Dhaka, Bangladesh
Mobile: +88 01710161588
E-mail: lokmanbbd@gmail.com
Dr. Mohammed Kamal Hossain
PhD (Silviculture)
Aberdeen University, UK
Professor
Institute of Forestry and Environmental sciences,
University of Chittagong, Chittagong - 4331
Bangladesh
Cell: +88 01819-837689
E-mail: mkhossain2008@yahoo.com
Preface
The treatment and disposal of industrial and residential sludge is an environmentally sensitive problem. Some traditional disposal routes, such as disposal at sea, are coming under pressure which necessitates finding alternatives. This book describes the effect of composted sludge on the growth of Acacia auriculiformis and Swietenia mahagoni seedlings in the nursery. The experiment was established and analyzed at the nursery of the Institute of Forestry and Environmental sciences, University of Chittagong, Bangladesh with a view to find out a suitable substitute of forest top soil for raising quality seedlings by using composted sludge incorporation with soil. The seedlings were evaluated in seven different treatments (including the control) for three months. Field germination, nodulation status, and physical growth parameters of seedlings namely; shoot height, root length, collar diameter, fresh and dry weight of shoot, root and nodule were recorded after one, two and three months of seed sown and chemical parameters of every treatment such as pH, organic carbon, nitrogen, phosphorus, potassium, chromium, nickel, manganese, cadmium and zinc were analyzed before and after the experiment. Field germination percentage of A. auriculiformis and S. mahagoni seeds were highest in treatment T5 and T6 respectively. Among the sludge amended soil, treatment T5 for A. auriculiformis and treatment T3 for S. mahagoni showed better performance of shoot and root growth compared to other treatments. The highest collar diameter was observed in the combination of soil and residential sludge (1:1) for both the species. The highest number of nodule was recorded from soil amended with residential sludge (2:1) and highest fresh and dry weight of nodule also found from the same combination. Shoot and root fresh weight of A. auriculiformis was highest in combination of soil and residential sludge in the ratio of (2:1). But for S. mahagoni highest shoot fresh weight was in treatment T3 and root fresh weight was in treatment T2, moreover, highest shoot and root dry weight was found in the same combination. Percentage of organic carbon and nutrients (nitrogen, phosphorus and potassium) content were highest in soil amended with residential sludge (1:1) both before and after the experiment over A. auriculiformis and S. mahagoni seedlings. From the study, it can be recommended that soil amended with residential sludge (2:1) on A. auriculiformis and soil amended with industrial sludge (3:1) on S. mahagoni provided better performance compared to other treatments.
LIST OF CONTENTS
Page No.
Preface 2
CHAPTER ONE
INTRODUCTION
1.1 Background 5
1.2 Objectives 6
CHAPTER TWO
LITERATURE REVIEW
2.1 Sludge 7
2.2 Present garbage disposal methods 7
2.3 Alternative disposal of sludge 7
2.4 Chemical composition and nutrients in sewage sludge 8
2.5 Effect of sludge on soil 9
2.6 Effect of sludge on nursery soil and seedling 9
CHAPTER THREE
MATERIALS AND METHODS
3.1 Description of the nursery site 10
3.1.1 Location 10
3.1.2 Soil 10
3.1.3 Climate 10
3.2 Materials used in the experiment 10
3.2.1 Treatment 10
3.2.2 Seeds and seed source 10
3.2.3 Potting mixture 10
3.3 Experimental methods 11
3.3.1 Composting of the sludge 11
3.3.2 Preparation of potting mixture 11
3.3.3 Design and layout of the experiment 11
3.3.4 Seed treatment 12
3.3.5 Seed sowing and seed quantity 12
3.4 Germination of the seeds 12
3.5 Transfer of seedlings from shade to sun 12
3.6 Maintenance and care of the seedlings 12
3.6.1 Watering 13
3.6.2 Weeding 13
3.7 Observation recorded 13
3.8 Determination of chemical parameters of sludge amended soil 13
3.8.1 Determination of PH 13
3.8.2 Determination of organic carbon 13
3.8.3 Determination of nitrogen, phosphorus and potassium
concentration 13
3.8.4 Determination of heavy metals content 13
CHAPTER FOUR
RESULT AND DISCUSSION
4.1 Results 15
4.1.1 Seed germination percentage 15
4.1.2 Height of the seedlings 16
4.1.3 Collar diameter of the seedlings 17
4.1.4 Nodulation and nodule number and their fresh and dry weight 18
4.1.5 Shoot and root fresh and dry weight 19
4.1.6 Chemical analysis of different media at the initial and final stage of the
experiment 21
4.1.7 Determination of chemical parameters of different media at the initial
and final stage of the experiment 26
4.2 Discussion 32
CHAPTER FIVE
CONCLUSION AND RECOMMENDATION
5.1 Conclusion 36
5.2 Recommendation 36
CHAPTER - 1
INTRODUCTION
Background
Application of sludge to land has been practiced in an attempt to dispose of industrial and residential waste and to gain potential fertilizer value from the application. Since, it contains many essential plant nutrients, sludge can be used as a plant growth medium. Several studies have shown that sludge addition provide significant benefit to crop growth (Gaynor and Halstead, 1976; Beckett et al., 1977). This is not surprising in view of elevated nitrogen, phosphorous and other nutrients levels in sludge (Sommers, 1977). Besides benefiting plant growth, sludge addition can change soil physical and chemical properties (Peles et al., 1996; Ramachandran and D’Soura, 1998; Gardiner et al., 1995; Jobra and Andres, 2000; Hossain and Miller, 2004). Pathogen levels can be reduced through decomposition (Zasoski, 1981). As forests are not food chain crops, many of the public health concerns and land application regulations should not be as critical as those associated with agricultural site (Cole et al., 1983). These changes will depend on the properties of the applied sludge and the quality of sludge applied (Zasoski, 1981). However, the moist, anaerobic qualities of sludge are not conducive to plant growth. These qualities can be alleviated by mixing sludge with a bulking agent and allowing the mixture to compost (Bledsoe, 1983).
Some countries move forward significantly in using industrial and residential sludge in agriculture and forest crops. This is one of the important safe disposal systems, becoming popular in some other countries. It has been found that everyday 300 to 350 tons garbage is generated in Dhaka (Bhuiyan, 1991). About 3,000 tons of garbage is generated in all metropolitan cities a day. Management of this waste costs about Tk. 200 million a year as against the collection of conservancy tax to the tune of Tk. 120 million a year (Majumder, 1996). Except for large cities like Dhaka and Chittagong, there is hardly any proper arrangement of collection and disposal of garbage in urban areas. Not only can the existing unhygienic crude dumping of garbage be avoided but the waste can be converted in to organic manure on a large scale.
Advantages of sewage sludge application in forestry over agriculture are because extensive areas of forest land and nurseries are available, sludge may be applied throughout the year unconstrained by the crop (Bayes et al., 1991), forests and nurseries are typically located in better drained sites and are not subject to the periodic flooding of alluvial agricultural areas, many of the forest areas and nursery soils are markedly deficient in the major nutrients that are found in the industrial sludge and wastewater, particularly nitrogen and phosphorous. Since the forests are not food chain crops, many of the public health concerns and land application regulations should not be as those associated with agricultural sites (Cole et al., 1983). Theoretically forest soils in the nursery have properties well suited to receive sludge and waste water additions, including high organic carbon content which will immobilize available nitrogen, a high infiltration rate which should minimize the potential for surface run off, and a perennial root system which should allow for year round uptake of available nutrients (Cole et al., 1983).
Bangladesh has a bright prospect for the expansion of Acacia auriculiformis and Swietenia mahagoni in plantation programs of both the Forest Department and other organizations due to their fast growth, well adaptability and easy propagation. That’s why most of the nurseries in private and public sector raise seedlings of these two species. A suitable potting media possessing with rich humus and organic matter is essential for quality seedling raising programs. Traditional use of potting media in Bangladesh is a mixture of cowdung and forest top soil, which is now becoming scarce due to loss of fertile top soil and unavailability of cowdung. Since the sludge possesses some nutrients and beneficial to nursery seedlings(Iqbal et al., 2007), the present study is in an aim to know the effects of industrial and residential sludge in the nursery stage, for the abatement of dependency on forest top soil and to find out alternative sludge disposal mean.
Objectives of the study
The main objectives of the study are as follows-
To assess the effect of sludge on germination and growth performance of Acacia auriculiformis and Swietenia mahagoni seedlings,
To determine the amount of nutrients uptakes by seedlings from sludge,
To identify the feasibility of the alternative use of sludge in nursery raising programs and
To find out whether the sludge has any effect on seedlings growth or not.
CHAPTER - 2
LITERATURE REVIEW
2.1 Sludge
Sewage sludge referred as bio-solid is being used in agriculture or cropland as a fertilizer and an organic amendment to improve physical, chemical and biological properties of soil (Singh and Agrawal, 2007; Hossain and Miller, 1994). Sewage sludge has been used as an economic organic fertilizer in land reclamation for many years where its nitrogen, phosphorous and organic matter content has been found to be an effective means of overcoming the nutrient and soil physical deficiencies common to the wide range of derelict land types. Sludge constitutes organic and inorganic substances. Industrial and residential sludge contain effluent from bathroom, wastes from kitchen, undigested garbage from drainage systems, sewage, urban run off, solid and liquid wastes from industry and agricultural wastes (Bhuiyan, 1991).
2.2 Present garbage disposal methods
Except for large cities like Dhaka and Chittagong there is hardly any proper arrangement of collection and disposal of garbage in urban areas. Even in Dhaka, the garbage disposal management is unsatisfactory, heaps of rotten garbage disposal are normal sights along city streets or neighboring lanes. There is very little evidence of garbage collection by formal municipal authorities from urban settlements. Usually the garbage goes through some degree of natural processing that produces a thick sludge and a watery effluent. Both the sludge and effluent is usually dumped in to a nearby river or other water body (Islam, 1992).
International experience shows that in England and Wales 95% household use underground channel for disposing waste, while the figure for USA is 75%, for Federal Germany is 80% and for Netherlands is 88%. The treatment and disposal of sludge is a costly and problematic concern for underdeveloped countries. In some regions of Britain it costs £10 million after the population of 1,00,000 (Bhuiyan, 1991).
2.3 Alternative disposal of sludge
Sludge can be used as a soil amendment, either for land reclamation or for increased plant growth. Since, sludge contains modest quantities of essential plant nutrients; it can be a useful plant fertilizer. Because it has high organic matter content, it can be a good soil conditioner (Bledsoe and Zasoski, 1981). The main advantage of the use of sewage sludge is the enrichment of the soil at a lower cost than is possible with inorganic fertilizers. Forested sites are increasingly receiving attention as potential sites for the disposal and biological recycling of both wastes water and sludge from industrial treatment plants (Cole et al., 1983). There are a number of obvious reasons for considering forest sites and nurseries as potential for the disposal and reuse of sewage sludge, e. g,
Extensive areas of forest land and nurseries are available.
Sludge may be applied throughout the year unconstrained by the crop (Bayes et al., 1991).
Forests and nurseries are typically located in better drained sites and are not subject to the periodic flooding of alluvial agricultural areas.
Many of the forest areas and nursery soils are markedly deficient in the major nutrients that are found in the industrial sludge and wastewater, particularly nitrogen and phosphorous.
As forests are not food chain crops, many of the public health concerns and land application regulations should not be as those associated with agricultural sites (Cole et al., 1983).
Theoretically forest soils in the nursery have properties well suited to receive sludge and waste water additions, including high organic carbon content which will immobilize available nitrogen, a high infiltration rate which should minimize the potential for surface run off, and a perennial root system which should allow for year round uptake of available nutrients (Cole et al., 1983).
However, the moist, anaerobic qualities of sludge are not conducive to plant growth. These qualities can be alleviated by mixing sludge with a bulking agent and allowing the mixture to compost (Bledsoe, 1981).
2.4 Chemical composition and nutrients in sewage sludge
The chemical composition of the sewage sludge is of great importance when developing recommendations for sludge application. Current recommendations are usually based on the fertilizer value (N, P and K) and on the concentrations of trace metals present in sludge (Sommers, 1977).
Sludge can not be easily characterized because of their highly variable composition, even when they are from the same source (Simon, 1989), and composition may be particularly variable when there are varying amounts of industrial and other non-domestic inputs to the sewage treatment plant (EPA, 1983). Sludge contains varying amounts of natural organic carbon, trace synthetic organics, macro and micro nutrients and heavy metals. The most common types of sludge contain proportionately high amounts of total N. Nitrogen is present primarily in two forms, a) mineral nitrogen which is immediately available to plants and b) organic form, which is released slowly over time (Riha et al., 1983). Total nitrogen content in domestic sludge’s may range from 1% to 15% by dry weight but is more commonly 3% to 6% of this being present as organic nitrogen. Phosphorous content is typically between 1% to 4% by dry weight while that of potassium range from 0.2% to 1% (McCalla et al., 1977). The amount of total potassium is low in sewage sludge, and its high solubility means that most of it remains in the effluent not in the sludge (EPA, 1983).
The most potential hazardous heavy metals in sludge are Zn, Cu, Ni, Mo and Cd which applied to soils in excessive amounts may reduce plant yields or impair the quality of food or fiber produced (Simmers, 1977). Heavy metals cause less concern when sludge is applied on forest land and nurseries, because forest is a non food chain. The greatest proportion of the pathogen population comes from industrial and residential sludge (Simon, 1989). Stabilized sludge, especially those derived from anaerobic digestion of which have been composed or chemically treated for pathogen control contain few pathogens and are usually safe for application to forest land and nurseries (Black, 1984; White, 1979).
Bledsoe and Zasoski (1981) analyzed the nutrient and heavy metal content of soil and sludge amended media, which are summarized in Table 2.1.
Table 2.1 Nutrient (nitrogen, phosphorous, potassium, calcium, magnesium) and heavy
metal (manganese, nickel, zinc, copper, cadmium) content of soil and sludge
amended media
|
Treatment |
Nutrients (%) |
Heavy Metals (ppm) |
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N |
P |
K |
Ca |
Mg |
Mn |
Ni |
Zn |
Cu |
Cd |
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Forest sub soil mixed with peat |
0.09 |
0.06 |
0.21 |
0.21 |
0.30 |
310 |
48 |
46 |
18 |
0.025 |
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Sludge |
2.30 |
1.50 |
0.16 |
0.16 |
0.29 |
480 |
170 |
2400 |
970 |
37 |
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Soil: sludge (3:1) |
0.29 |
0.17 |
0.19 |
0.19 |
0.27 |
330 |
59 |
210 |
95 |
3 |
|
Composted sludge |
0.71 |
0.51 |
0.09 |
0.09 |
0.09 |
140 |
76 |
290 |
290 |
14 |
2.5 Effect of sludge on soil
It is obvious that, as with other organic materials, sewage sludge improves soil physical and chemical properties (Page el al., 1983; Guidi and Hall, 1984). A large portion of the ammonium nitrogen may be lost due to volatilization if the sludge is surface applied (Ryan et al., 1973). If liquid sludge is incorporated in to the soil or dewatered sludge is applied then there is no loss from volatilization (EPA, 1983; Harding et al., 1985). Gupta et al., (1977), Webber (1978), Khaleel et al., (1981), Peterson et al., (1982) and Hall and Coker (1983) all found sludge application decreased the soil bulk density. Berry (1986) found significantly more nitrogen, phosphorous, organic matter and increased PH in soil from sludge treated plots.
Mixing soil with sludge is of considerable interest and importance in sludge utilization. Data presented by Riekerk and Zasoski (1979) have shown that a dilution of nutrients in sludge took place when sludge was mixed with soil. Mixing of sludge and soil resulted in increased nutrient based on soil values, but a dilution relative to initial sludge content. Table 2.2 shows the results of mixing sludge with soil.
Table 2.2: Change in nutrient content of soil after mixing with sludge and comparison
with the nutrient content of soil, sludge and compost (Riekerk and Zasoski,1979)
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Treatment |
N (%) |
P (%) |
K (%) |
Ca (%) |
Mg (%) |
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Soil |
0.09 ±0.01 |
0.06 ±0.005 |
0.21 ±0.005 |
0.21 ±0.01 |
0.30 ±0.01 |
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Sludge |
2.30 ±0.25 |
1.50 ±0.11 |
0.16 ±0.006 |
0.16 ±0.10 |
0.29 ±0.04 |
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Soil: Sludge (3:1) |
0.29 ±0.03 |
0.17 ±0.02 |
0.19 ±0.01 |
0.19 ±0.10 |
0.27 ±0.01 |
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Compost |
0.71 ±0.03 |
0.51 ±0.03 |
0.09 ±0.002 |
0.09 ±0.01 |
0.09 ±0.004 |
2.6 Effect of sludge on nursery soil and seedling
The effect of sewage sludge application to agricultural soils has been intensively investigated (Chaney et al., 1977; Kardos et al., 1977) while forest and nursery soils have received less attention (Smith and Evans, 1977). However, wastewater sludge is now being applied with increasing frequency to forest and nursery soils. Experimental treatments and growth trials covering a range of species and stages of growth have shown a wide range of response.
The application of composted municipal sludge by incorporation into the seed bed, prior to establishing poplar and white pine seedlings in Maryland produced significant height growth benefits for the poplar in the second year (McIntosh et al., 1984). Lombardy poplar and various hybrid poplars showed marked increases in productivity in the Pacific Northwest when fertilized with dewatered municipal sludge (Cole, 1982).
In a pot experiment where sewage was used and water did not limit growth, Salix alba gave the best result (Tihanyi, 1980). Three treatments of different levels of sewage water and a control with clean water irrigation were used in this experiment. The sewage provided 285, 475 and 711 kg/ha/yr nitrogen at different levels of disposal. The best growth was achieved with the highest dose, resulting in the biomass production increases for Salix alba, Robusta and Italian Poplar I- 214 of 239%, 219% and 196% respectively compared with treatment with 1200mm/year clear water. The treatment with clear water produced 16- 20% less biomass than the treatment with the same amount of sewage.
Bledsoe and Zasoski (1981) reported that, sludge mixed with soil a good soil amendment, since sludge increased the fertility of the soil. Seedlings grew 2-3 times taller and produced 2-5 times more biomass in the soil: sludge mixture. Foliar nitrogen content of seedlings grown in this mixture was 50- 150 % greater than that of seedlings grown in soil. The use of mixture of soil: sludge was superior to use of sludge alone, or sludge composted with sawdust.
CHAPTER - 3
MATERIALS AND METHODS
3.1 Description of the nursery site
3.1.1 Location
The study was conducted during the month of February to June in the nursery of Institute of Forestry and Environmental Sciences, University of Chittagong, Chittagong, Bangladesh.
3.1.2 Soil
The soil used in the nursery was moderately coarse to fine textured. It has a grey to olive grey; sandy loams sub soil moderate coarse and medium angular blocky structure.
3.1.3 Climate
The nursery site enjoys a tropical monsoon climate characterized by hot, humid summer and cool, dry winter. Temperature was 15°C in the month of February and 31°C in the month of May. Relative humidity was the lowest (64%) in February and highest (95%) in June month.
.
3.2 Materials used in the experiment
3.2.1 Treatment
There were 7 treatments of different mixtures including one control treatment for each species. The treatments and their combination are given in the Table 3.1.
Table 3.1: Treatments and their combinations used to carry on the experiment for both
the species
|
Treatments |
Combination |
Ratio |
No. of replication |
No. of seedlings |
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To (control) |
Valley soil |
--- |
3 |
45 |
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T1 |
Soil: industrial sludge |
1:1 |
3 |
45 |
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T2 |
Soil: industrial sludge |
2:1 |
3 |
45 |
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T3 |
Soil: industrial sludge |
3:1 |
3 |
45 |
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T4 |
Soil: residential sludge |
1:1 |
3 |
45 |
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T5 |
Soil: residential sludge |
2:1 |
3 |
45 |
|
T6 |
Soil: residential sludge |
3:1 |
3 |
45 |
3.2.2 Seeds and seed source
Seeds of A. auriculiformis and S. mahagoni were collected from the nursery of Institute of Forestry and Environmental Sciences, University of Chittagong, Chittagong, Bangladesh.
3.2.3 Potting mixture
Polybags of 23 cm × 15 cm (9" × 6") in size were used in the experiment. Soil were collected from the valley of adjacent hills, 6 weeks before the filling up of the bags and heaped in the nursery for decomposition. Industrial sludge was collected from the drain which is used for the discharge of textile industrial sewage sludge at Oxygen area and residential sludge was collected from Khulshi residential area in Chittagong city. The mixtures were made more or less uniform before filling up of the polybags and were freed from root splinters or other foreign materials.
3.3 Experimental methods
3.3.1 Composting of the sludge
The collected industrial and residential sludge were kept as a mound for aerobic decomposition of the sludge.
3.3.2 Preparation of potting mixture
Collected soil and sludge were dried in sun and sieved through 1.6 cm and 3.2 cm wire mesh respectively. Six hundred and thirty polybags of size 23 cm × 15 cm (9" × 6") were used. Three hundred and fifteen polybags were used for each species viz., A. auriculiformis and S. mahagoni. The ingredients for each of the treatment were mixed thoroughly and the polybags were filled.
3.3.3 Design and layout of the experiment
The experiment was established in a Completely Randomized Design (CRD) with three replications. The treatments were allotted completely at random. The layout of the experiment is given in figures 3.1 and 3.2 for A. auriculiformis and S. mahagoni respectively. Seven treatments of growing media and their combination for both the species are as follows:
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Figure 3.1: Layout of the design for A. auriculiformis
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3.3.4 Seed treatment
Seeds of A. auriculiformis were treated by soaking in hot water for 30 seconds before sowing in the pre-filled polybags.
3.3.5 Seed sowing and seed quantity
Though it was dry season, initially the experiment was set inside the nursery shed to protect the seedlings from intense sunlight. Two seeds per poly bag were sown for each of the species on 26th March, 2008 and excess seedlings of inferior quality were removed after germination.
3.4 Germination of the seeds
Within seven days of seed sown first germination was noticed for both the species. Initially the growth rate of A. auriculiformis was higher than that of S. mahagoni. After two weeks 40-60 % of the viable seeds were germinated. After three weeks 70-90 % of the viable seeds were germinated. Watering was done at every day for both the species to support the germination and seedling growth.
3.5 Transfer of seedlings from shade to sun
After one month of the seed sowing in the polybags, the seedlings were transferred from nursery shed to permanent nursery bed. There was no mortality at the time of transferring seedlings.
3.6 Maintenance and care of the seedlings
Maintenance is the most essential operation in the nursery for the proper management of quality planting stock.
3.6.1 Watering
For the frequent growing of planting materials, water is essential. This is why, everyday watering was carried out. Since the season was dry for the first two months of the study, watering was done by fine shower which could not disturb the young, delicate seedlings physically.
3.6.2 Weeding
Weeds make competition with the crops for nutrients which is the ultimate result of poor performance of seedlings in the nursery. So, regular removal of weeds, grasses etc. were done as far as possible.
3.7 Observation recorded
The investigation on A. auriculiformis and S. mahagoni were carried out during the period March to June, 2008.The germination was completed within 19 days in both the species. After completion of the germination, data were collected on three steps i.e. in three consecutive months. At the end of every month five seedlings from each treatment were randomly selected and harvested to determine the shoot height, root length, collar diameter, and nodule number, fresh and dry weight of stem, root, leaf and nodule. Different chemical parameters of different treatments were taken in two stages such as treatment before the experiment and after the experiment.
3.8 Determination of chemical parameters of sludge amended soil
3.8.1 Determination of pH
For the determination of pH required equipments are beaker, electric balance, glass rod, distilled water and pH meter. pH of all samples was measured before and after the experiment. For each treatment, 20 g sample was diluted with 40 ml water by using glass rod. Finally, the reading was recorded with the help of pH meter.
3.8.2 Determination of organic carbon and organic matter
Organic carbon was determined by wet oxidation with 0.167M K2Cr2O7 and by subsequent titration with 0.1M (NH4)2 Fe (SO4)2. 6H2O. Organic matter is determined by the multiplication of the result of organic carbon content with 1.72.
3.8.3 Determination of nitrogen, phosphorus and potassium content
These parameters were determined in the laboratory of Institute of Forestry and Environmental Sciences, University of Chittagong, Chittagong. Nitrogen was determined colorimetrically following block digestion with sulfuric acid. Potassium was determined by drying of samples and ashed at 4750C and finally dissolved in concentrated nitric acid. Phosphorus concentration was determined colorimetrically.
3.8.4 Determination of heavy metals content
The total content of acid extractable heavy metals was determined in 1 g sample from each combination using wet oxidation with the concentrated HNO3 and 3% H2O2. The metals were determined by atomic absorption spectroscopy with the Analyst-300 (Perkin- Elmer).
T0 T6
T5 T4
T3 T2 T1
Plate no. 1: Seedlings of 3-month old A. auriculiformis in the nursery just before
harvesting
T0
T6 T5
T4 T3
T2 T1
Plate no. 2: Seedlings of 3-month old S. mahagoni in the nursery just before
harvesting
CHAPTER – 4
RESULTS AND DISCUSSION
4.1 Results
Physical parameters of the seedlings were measured at a regular interval of 1-month. At the end of every month shoot height, root length, collar diameter, shoot fresh weight, root fresh weight, shoot dry weight and root dry weight for both A. auriculiformis and S. mahagoni and moreover, for A. auriculiformis number of nodule, nodule fresh weight and dry weight were measured and calculated.
4.1.1 Seed germination
Seed germination was highest (90%) in treatment T5 and lowest (63%) in treatment T0 for A. auriculiformis (Table 4.1). The analysis of variance showed that seed germination percentage varied significantly among different treatments. Seeds germination was increased in different combination of sludge amended soil compared with control treatment.
Table 4.1:Germination rate of A. auriculiformis seeds in different combinations of soil and
sludge
|
Treatment |
Number of seed sown |
Number of germinated seedlings |
Percentage |
|
T0 |
90 |
57 |
63 d* |
|
T1 |
90 |
66 (+9) |
73 c (+10) |
|
T2 |
90 |
69 (+12) |
77 b (+14) |
|
T3 |
90 |
71 (+14) |
79 b (+16) |
|
T4 |
90 |
68 (+11) |
75 b (+12) |
|
T5 |
90 |
81 (+24) |
90 a (+27) |
|
T6 |
90 |
78 (+21) |
87 ab (+24) |
*Means followed by the same letter(s) in the same column do not vary significantly at P<0.05,
according to Duncan’s Multiple Range Test (DMTR); +/– value in the parentheses indicate
the increased or decreased value from control treatment
In contrast, highest (92%) seeds germination were found in treatment T6, and the lowest (70%) were in treatment T0 for S. mahagoni (Table 4.2). Analysis of variance showed that seeds germination were varied significantly among different treatments and all the treatments provided the increased germination rate compared with control.
Table 4.2:Germination rate of S. mahagoni seeds in different combinations of soil and sludge
|
Treatment |
Number of seed sown |
Number of germinated seedlings |
Percentage |
|
T0 |
90 |
63 |
70 d* |
|
T1 |
90 |
73 (+10) |
81 bc (+11) |
|
T2 |
90 |
71 (+8) |
79 bc (+9) |
|
T3 |
90 |
69 (+6) |
77 c (+7) |
|
T4 |
90 |
76 (+13) |
84 ab (+14) |
|
T5 |
90 |
78 (+15) |
87 ab (+17) |
|
T6 |
90 |
83 (+20) |
92 a (+22) |
*Means followed by the same letter(s) in the same column do not vary significantly at P<0.05,
according to Duncan’s Multiple Range Test (DMTR); +/– value in the parentheses indicate
the increased or decreased value from control treatment
4.1.2 Height of the seedlings
Height is one of the most important parameter to get an idea about the growth of the growing stocks in the nursery. Mean height of each treatment was measured in every 1-month interval. It is seen that the height of 1, 2 and 3-month old seedlings of A. auriculiformis was highest in the treatment T5. The lowest height was exhibited in the control treatment T0 (Tables 4.3, 4.4 and 4.5).
Table 4.3: Effect of different combinations of soil and sludge on shoot and root length of
1-month old A. auriculiformis and S. mahagoni seedlings
|
Treatment |
A. auriculiformis |
S. mahagoni |
||
|
Shoot length (cm) |
Root length (cm) |
Shoot length (cm) |
Root length (cm) |
|
|
T0 |
18.3 b* |
7.4 b |
15.2 b |
3.1 bc |
|
T1 |
21.6 b (+3.3) |
7.2 b (-0.2) |
17.3 ab (+2.1) |
4.2 b (+1.1) |
|
T2 |
29.1 ab (+10.8) |
11.5 ab (+4.3) |
19.4 a (+4.2) |
4.0 b (+0.9) |
|
T3 |
42.2 a (+23.9) |
10.2 ab (+2.8) |
22.2 a (+7.0) |
6.2 a (+3.1) |
|
T4 |
39.4 a (+21.1) |
16.9 a (+9.5) |
11.6 bc (-3.6) |
8.5 a (+5.4) |
|
T5 |
44.0 a (+25.7) |
13.6 ab (+6.2) |
7.6 c (-7.6) |
5.7 ab (+2.6) |
|
T6 |
29.5 ab (+11.2) |
6.8 b (-0.6) |
18.6 ab (+3.4) |
7.2 a (+4.1) |
*Means followed by the same letter(s) in the same column do not vary significantly at P<0.05,
according to Duncan’s Multiple Range Test (DMTR); +/– value in the parentheses indicate
the increased or decreased value from control treatment
Shoot and root length of 1-month old seedlings of A. auriculiformis were significantly differs at 5% level of significance among the treatments. Though treatment T0 and T1 did not vary significantly, shoot height was increased 3.3 cm and root length decreased 0.2 cm from treatment T0 to treatment T1. Shoot and root length were highest in treatment T5 and T4 respectively for three consecutive months. Moreover, the analyses of variance showed significant difference (at 5% level) in shoot and root length of S. mahagoni seedlings among different treatments. The highest shoot height and root length were observed in treatment T3 and T4 respectively in three consecutive months. In 3-month old S. mahagoni seedlings highest and lowest shoot height were 49.2 cm and 33.5 cm in the treatment T3 and T0 respectively but treatment T4 gave the highest root height (Tables 4.3, 4.4 and 4.5).
Table 4.4: Effect of different combination of soil and sludge on shoot and root length
of 2-month old A. auriculiformis and S. mahagoni seedlings
|
Treatment |
A. auriculiformis |
S. mahagoni |
||
|
Shoot length (cm) |
Root length (cm) |
Shoot length (cm) |
Root length (cm) |
|
|
T0 |
35.2 b* |
11.5 b |
22.4 b |
4.2 b |
|
T1 |
37.2 b (+2.0) |
13.2 b (+1.7) |
26.0 ab (+4.0) |
7.4 ab (+3.2) |
|
T2 |
43.5 ab (+8.3) |
15.2 ab (+3.7) |
29.1 a (+6.7) |
6.7 b (+2.5) |
|
T3 |
63.8 a (+28.6) |
16.3 ab (+4.8) |
36.0 a (+13.6) |
8.9 ab (+4.7) |
|
T4 |
59.4 a (+24.2) |
24.5 a (+13.0) |
33.5 a (+11.1) |
12.7 a (+8.5) |
|
T5 |
64.6 a (+29.4) |
19.4 ab (+7.9) |
24.3 b (+1.9) |
9.6 a (+5.4) |
|
T6 |
41.3 ab (+6.1) |
12.7 b (+1.2) |
29.8 a (+7.4) |
10.4 a (+6.2) |
*Means followed by the same letter(s) in the same column do not vary significantly at P<0.05,
according to Duncan’s Multiple Range Test (DMTR); +/– value in the parentheses indicate
the increased or decreased value from control treatment
Shoot height of 2-month old seedlings of S. mahagoni was highest (36 cm) in treatment T3 and lowest (22.4 cm) in treatment T0; on the other hand, root height was highest (12.7 cm) in treatment T4 and lowest (4.2 cm) in control. Though root length in treatment T0 and T2 of 2-month old S. mahagoni seedlings do not varied significantly, root length was increased 2.5 cm in treatment T2 in comparison with T0 (Table 4.4).
Table 4.5: Effect of different combination of soil and sludge on shoot and root length
of 3- month old A. auriculiformis and S. mahagoni seedlings
|
Treatment |
A. auriculiformis |
S. mahagoni |
||
|
Shoot length (cm) |
Root length (cm) |
Shoot length cm) |
Root length (cm) |
|
|
T0 |
51.6 b* |
14.1 b |
33.5 b |
10.2 b |
|
T1 |
58.4 ab (+6.8) |
17.2 b (+3.1) |
36.7 ab (+3.2) |
12.4 ab (+2.2) |
|
T2 |
68.3 a (+16.7) |
19.4 ab (+5.3) |
38.1 a (+4.6) |
11.6 b (+1.4) |
|
T3 |
79.1 a (+27.5) |
21.6 ab (+7.5) |
49.2 a (+15.7) |
12.3 ab (+2.1) |
|
T4 |
74.2 a (+22.6) |
32.2 a (+18.1) |
42.5 a (+9.0) |
16.4 a (+6.2) |
|
T5 |
79.7 a (+28.1) |
26.8 a (+12.7) |
39.7 a (+6.2) |
13.0 ab (+2.8) |
|
T6 |
53.2 ab (+1.6) |
18.4 ab (+4.3) |
41.3 a (+7.8) |
14.9 a (+4.7) |
*Means followed by the same letter(s) in the same column do not vary significantly at P<0.05,
according to Duncan’s Multiple Range Test (DMTR); +/– value in the parentheses indicate
the increased or decreased value from control treatment
4.1.3 Collar diameter of the seedlings
Collar diameter is one of the most important factor to consider vigor and healthy seedlings. It is crystal clear from the table that the highest collar diameter was found in the treatment T4 and lowest was in treatment T6, showing out 7.4 mm and 4.5 mm respectively for 3-month old seedlings of A. auriculiformis. The least collar diameter of 1 and 2- month old A. auriculiformis seedlings were measured in the treatment T1 and T6 in spite of their non-significant difference at 5% level with the treatment T0.
Table 4.6: Effect of different combination of soil and sludge on collar diameter of 1, 2 and
3-month old A. auriculiformis seedlings
|
Treatment |
1-month |
2-month |
3-month |
|
T0 |
2.8 b* |
3.9 ab |
5.2 b |
|
T1 |
2.4 b (-0.4) |
3.6 b (-0.3) |
5.5 ab (+0.3) |
|
T2 |
3.5 ab (+0.7) |
5.2 a (+1.3) |
7.1 a (+1.9) |
|
T3 |
3.8 a (+1.0) |
4.8 a (+0.9) |
6.5 a (+1.3) |
|
T4 |
4.0 a (+1.2) |
5.0 a (+1.1) |
7.4 a (+2.2) |
|
T5 |
4.3 a (+1.5) |
5.2 a (+1.3) |
6.8 a (+1.6) |
|
T6 |
2.5 b (-0.3) |
3.3 b (-0.6) |
4.5 b (-0.7) |
*Means followed by the same letter(s) in the same column do not vary significantly at P<0.05,
according to Duncan’s Multiple Range Test (DMTR); +/– value in the parentheses indicate
the increased or decreased value from control treatment
In contrary, when S. mahagoni was considered it was found that the lowest collar diameter was observed in the treatment T0 and highest was in treatment T4 given the values 3.5 mm and 5.2mm respectively for 3-month old seedlings. Collar diameter of S. mahagoni seedlings of different treatments varied from control at 5% level of significance. The lowest value was observed in control over the experiment
Table 4.7: Effect of different combination of soil and sludge on collar diameter of 1, 2 and
3-month old S. mahagoni seedlings
|
Treatment |
1-month |
2-month |
3-month |
|
T0 |
1.8 b* |
2.5 bc |
3.5 bc |
|
T1 |
2.4 ab (+0.6) |
3.3 b (+0.8) |
4.2 b (+0.7) |
|
T2 |
2.6 ab (+0.8) |
3.5 ab (+1.0) |
4.5 ab (+1.0) |
|
T3 |
3.0 a (+1.2) |
3.8 ab (+1.3) |
4.8 a (+1.3) |
|
T4 |
3.6 a (+1.8) |
4.5 a (+2.0) |
5.2 a (+1.7) |
|
T5 |
2.4 ab (+0.6) |
3.5 ab (+1.0) |
4.2 b (+0.7) |
|
T6 |
2.9 a (+1.1) |
3.5 ab (+1.0) |
4.4 ab (+0.9) |
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