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Wastewater sludge and sludge biochar addition to soils for biomass production from Hyparrhenia hirta
Ecological Engineering 82 (2015) 345–348
Contents lists available at ScienceDirect
Ecological Engineering journal homepage: www.elsevier.com/locate/ecoleng
Short communication
Wastewater sludge and sludge biochar addition to soils for biomass production from Hyparrhenia hirta Mustafa K. Hossaina,b , Vladimir Strezova,* , Lester McCormickc , Peter F. Nelsona a
Department of Environmental Sciences, Faculty of Science and Engineering, Macquarie University, NSW 2109, Australia Elizabeth Macarthur Agricultural Institute, NSW Department of Primary Industries, Woodbridge Road, Menangle, NSW 2568, Australia c NSW Department of Primary Industries, 4 Marsden Park Road, Calala, NSW 2340, Australia b
A R T I C L E I N F O
A B S T R A C T
Article history: Received 3 February 2015 Received in revised form 15 April 2015 Accepted 23 May 2015 Available online xxx
The aim of the study was to determine the performance of sludge biochar compared to unprocessed wastewater sludge on production of Coolatai grass (Hyparrhenia hirta) as a potential forage and energy crop species. Pot trials were conducted to determine the nutritive quality and yield of Coolatai grass using chromosol soil amended with wastewater sludge and sludge biochar. The application of biochar combined with fertiliser was found to have the highest effect on the yield producing more than double of the plant dry matter comparing to unamended chromosol soil conditions. The combination of biochar and fertiliser treatment also increased some of the important chemical characteristics of Coolatai grass, such as the metabolisable energy and crude protein composition compared to control, wastewater sludge and fertiliser treatments. ã2015 Elsevier B.V. All rights reserved.
Keywords: Coolatai grass Wastewater sludge Biochar Nutritive value
1. Introduction Coolatai grass (Hyparrhenia hirta) was first introduced to the northern New South Wales, Australia from South Africa and the Mediterranean region in the 1940s. Since its introduction to Australia the grass has spread along roadside and grazing lands on many properties (McCormick et al., 2002). The grass is now available in the northern New South Wales (Wheeler et al., 1982) and in traprock soils of the southern Queensland (Tothill and Hacker, 1983). The plant grows well in warm season, it is extremely drought resistant (McCormick et al., 2002) but it is sensitive to frost in winter. Coolatai grass’ ideal growth conditions are between the temperatures of 30–40 C achieving growth of up to around 1 m in height. Coolatai grass is reported to have potential grass forage value (McCormick and Lodge, 1991). This grass is a valuable species at high stocking rates in Western Australia (Humphries, 1959; Rogers et al., 1979) and also can be cultivated under saline conditions (Rogers and Bailey, 1963), which may be useful to control the watertable and reduce soil salinity. Due to the fast growth rates and drought resistant condition requirements, Coolatai grass is potentially a target forage and energy crop species as it has potential to supplement the nutritional feed for animals during dry
* Corresponding author. Tel.: +61 2 9850 6959. E-mail address: [email protected] (V. Strezov). http://dx.doi.org/10.1016/j.ecoleng.2015.05.014 0925-8574/ ã 2015 Elsevier B.V. All rights reserved.
season or it can be used as biomass feedstock for energy production. However, production of fast growing crops as animal forage or as energy crops demands dedicated agricultural land and requires nutrients for cultivation. One of the options to alleviate these requirements is cultivation of fast growing crops in low quality soils using nutrient rich wastewater (sewage) sludge as a fertiliser. Biochars are carbon rich materials produced through pyrolysis of biomass, which are also potential nutrient supplying materials known to promote soil quality (Hossain et al., 2010), can be used to cultivate fast growing forage and energy crops and improve soil quality through ecological restoration (Xu et al., 2013). Biochar produced from wheat straw has been shown to reduce the carbon mineralisation rate in saline affected soils (Junna et al., 2014). The process of biochar production from wastes or weeds (Kumar et al., 2013) can also serve as an option for developing sustainable waste management and value adding strategy. In case of the wastewater sludge, however, it is still uncertain if the biochar produced from the sludge would perform more favourably in agricultural production of fast growing crops comparing to raw wastewater sludge application. The aim of this research is to investigate the effect of wastewater sludge and sludge biochar on the production of Coolatai grass and to evaluate the effect of soil amendment on the nutritional and energy value of this neglected pasture species. Biochar produced from wastewater sludge has been shown to promote production and growth of food crops while sequestering carbon and managing this waste more
346
M.K. Hossain et al. / Ecological Engineering 82 (2015) 345–348
effectively (Hossain et al., 2009, 2011). However, the effect of biochar on cultivation of energy and forage crops has still not been assessed. This study was designed to determine the variations of different nutrient levels, dry matter production and energy value of Coolatai grass cultivated in a soil amended with wastewater sludge, which is a by-product of the wastewater treatment industry, and sludge biochar which is produced through a volume reducing pyrolysis process of the wastewater sludge. 2. Materials and methods
pot with a size of 19 cm in height, 15 cm in diameter at the bottom and 20 cm in diameter at the top. 2.4. Chemical composition analysis At the end of the 11 weeks pot trial experiments the plants were harvested from each pot and oven dried at 80 C to constant weight to determine the dry matter production. The samples were then ground to 0.8 mm particle size and analysed for chemical composition in a Bruker MPA FTIR following the analytical method described by AFIA, 2007.
2.1. Soil 2.5. Statistical analysis A composite soil sample was collected 0.1 m of the top soil layer from the paddock of Centre for Recycled Organic Agriculture (CROA) site near Camden, south west of Sydney. According to the Australian soil classification the soil used for this study is chromosol (Isbell, 1996). The agricultural properties of the soil are shown in Table 1. The soil was found to be low in total nitrogen (0.13%), while the ammonium nitrogen was 3.6 mg kg 1 and phosphorus was 15 mg kg 1. The soil was acidic in nature.
One way analysis of variance and post-hoc Student-NewmansKules (SNK) test was performed using GMAV5 (Underwood and Chapman, 2007) to determine the significance of differences of the values of chemical composition of Coolatai grass grown with wastewater sludge and sludge biochar. The variation and reproducibility of the data were tested using the Cochran’s test. 3. Results and discussion
2.2. Wastewater sludge and biochar production 3.1. Proximate and ultimate analysis The wastewater sludge was collected from an urban wastewater treatment plant in Sydney. Some of the chemical properties of the sludge are shown in Table 1. The sludge sample is found to be high in ammonium nitrogen (7275 mg kg 1), low in nitrate nitrogen (35 mg kg 1) and acidic in nature. The biochar was produced through pyrolysis using a fixed bed reactor at a temperature of 550 C and heating rate of 10 C mim 1. The agronomic properties of the wastewater sludge biochar are shown in Table 1. The biochar was found to be alkaline in nature, low in total N (2.3%) and high in phosphorus (1100 mg kg 1). 2.3. Pot experiments Coolatai grass (Hyparrhenia hirta) sample was collected from Tamworth, northern part of New South Wales as a target species to carry out the pot trial experiments. The experiments were conducted under a temperature controlled (30–35 C) glass house conditions. The experimental design was factorial randomised block design with six treatments (i) control (CP) (ii) soil with wastewater sludge (SS) (iii) soil with wastewater sludge biochar (SB) (iv) soil with wastewater sludge and fertiliser (SSF) (v) soil with wastewater sludge biochar and fertiliser (SBF) and (vi) soil with fertiliser (SF). Each treatment was carried out in five replicates. The application rate of sludge and biochar was 10 t ha 1. There is no recommend rate of fertiliser application for cultivation of Coolatai grass. The fertiliser application used in the current study was equivalent to 120 kg ha 1 of nitrogen; 70 kg ha 1 of phosphorus and 80 kg ha 1 of potassium based on previous investigation conducted by Hossain et al. (2010) who demonstrated benefits to soil and plants by the similar fertiliser application rate. Six kg of air dried soil was packed in each cylindrical plastic Table 1 Agricultural properties of soil, wastewater sludge and sludge biochar used in the pot experiments.
The main physical and chemical characteristics of Coolatai grass are given in Table 2. With 5.6% ash content, the grass was found to have higher ash composition than most woody biomass species (Strezov et al., 2003), which are in the order of 0.2–0.3% and was higher than some grass species, such as elephant grass, which was reported to have ash content of approximately 3% (Strezov et al., 2008). The fixed carbon content was in the same order as wood and grass species measured previously, while the volatile matter was somewhat lower. Consequently, the calorific value of the Coolatai grass, estimated with a bomb calorimeter at 16.9 MJ/kg, is slightly lower than the woody and grass species determined previously. 3.2. Metabolisable energy Metabolisable energy of forage is the vital limiting nutrient for animals in a pasture based system and maximised energy density of the pasture feed is important for growth and healthy body function of the livestock. The metabolisable energy values of Coolatai grass under the prescribed treatment conditions are given in Table 2. There is a significant difference of metabolisable energy in the Coolatai grass cultivated under SF, SS and CP treatments comparing with SBF treatment. The highest metabolisable energy was found in the SBF treatment (8.4%) followed by SSF (8%) and SB (7.9%) treatment conditions. The lowest metabolisable energy content was detected in the control (CP) treatment (7.3%). These
Table 2 Proximate, ultimate analysis and calorific value of Coolatai grass. Proximate analysis Moisture % Ash % 7.5 5.6
Properties
Unit
Soil
Wastewater sludge
Biochar
Ultimate analysis Carbon% Hydrogen% 42.6 5.38
EC pH (CaCl2) Total N P (Colwell) Ammonium N (KCL extract) Nitrate N (KCL extract)
dS m-1 pH unit % mg kg 1 mg kg 1 mg kg 1
0.09 4.6 0.13 15 3.6 4.9
11.9 4.4 3.3 747 7275 35
1.9 8.2 2.3 1100 11 0.49
Metabolisable energy (MJ/kg DM) CP SS 7.3 7.7 0.21 0.08 Calorific value (ML/kg) 16.9 Least Significant difference (LSD) = 0.59
Nitrogen% 1.7
Volatile matter% 69.4
Fixed carbon% 17.5
Sulphur% 0.23
Oxygen% 37
SB 7.9 0.26
SSF 8.0 0.17
SSF 8.4 0.18
SF 7.6 0.23
M.K. Hossain et al. / Ecological Engineering 82 (2015) 345–348
findings highlight that the combined effect of biochar and fertiliser used for the SBF treatment maximises the metabolisable energy availability in Coolatai grass. The results presented here are within similar range to the metabolisable energy measured previously in the leaf of kikuyu grass at 9.2% and in the stem measured at 7.4% (Fulkerson, 2007). 3.3. Chemical composition The effect of treatment conditions on the chemical composition of Coolatai grass is shown in Table 3. The biochar was found to significantly increase the crude protein content in the grass in both treatments with and without fertiliser (SBF and SB). The crude protein content of SBF treatment significantly varied with all other treatments. Protein is a vital parameter for all livestock diets but the required amount varies between animals. For instance, the required crude protein for mature beef cows is 10.5% (Hall et al., 2001), which was achieved in case of SB and SBF treatments. On the other hand the required crude protein for young goats is 14% and this amount was measured only with the grass produced for the combined fertiliser with biochar (SBF) treatment. It appears that in case of all treatments where biochar was not applied, including fertiliser treatment, the crude protein content of the Coolatai plant does not meet the minimum requirements as a feed for livestock. Application of wastewater sludge biochar increased the amount of crude protein of Coolatai grass possibly because the biochar contains bioavailable nitrogen and phosphorus, which are directly involved as protein and nucleic acid forming constituents (Ward, 1959). Neutral detergent fibre, acid detergent fibre and acid detergent lignin in Coolatai grass decreased in the case of biochar, sludge and the fertiliser treatments, while increasing its dry matter and dry organic matter digestibility comparing to control treatment. The neutral detergent fibre (NDF) of the plant is a measure used to predict intake potential of the plant by livestock (Ball et al., 2001). In the results shown in Table 3 the highest NDF was detected for the control pot conditions (66.9%), while the lowest was
347
determined for the SBF treatment (60.2%) conditions. The SBF treatment significantly decreased the NDF of the grass compared to the control treatment. The lowest NDF value measured for the case of SBF treatment is still well above the NDF values reported for smooth brome grass and quackgrass at 56% (Marten and Andersen, 1975). The acid detergent fibre (ADF) concentration in the plants is a parameter used to determine digestibility of a plant. In the case of this study the control treatment conditions (CP) produced plants with the highest ADF (40%) concentration followed by SF, SB, SS, SSF treatment conditions. The SBF treatment was found to produce grass with the lowest ADF concentration at 35%, however this concentration is still well above the reported ADF values for other plants, such as giant foxtail (33%), yellow foxtail (30%) (Marten and Andersen, 1975) and alfalfa forage at early bloom (23%) (Temme et al., 1979). Hence, addition of biochar, sludge and fertiliser will have no significant adverse impact on the quality of the intake potential and digestibility of the plant. Cellulose, hemicellulose and lignin content of Coolatai grass are shown in Table 3. These parameters are important as cellulose and hemicellulose in forage are the main sources of energy to ruminants (Merkel et al., 1999). There is no significant difference in cellulose content among the treatments compared to control except the SBF treatment. SBF treatment showed significant difference of the cellulose content within the treatments. In this work, addition of biochar and sludge to the soil with and without fertiliser, decreased the cellulose content of Coolatai grass. As discussed by Ward (1959) the chemical composition of forage may be altered through the use of fertilisers and it is very likely that the addition of nutrients through the biochar and sludge in the current work may have reduced the amount of cellulose in the grass. The highest hemicellulose content was in the grass cultivated under the SS treatment which is significantly different to the SBF treatment. The highest lignin content was in the SB treatment, which showed significant difference to the control and all other treatments. The biochar addition to soil was also found to increase the lignin and have neutral effect on the hemicellulose content of
Table 3 Chemical composition of Coolatai grass. Parameters (%) Neutral detergent fibre
CP 66.9 0.40
SS 64.8 0.86
SB 65.8 1.68
SSF 62 2.25
SBF 60.2 2.88
SF 65.0 1.41
LSD 5.01
Acid detergent fibre
40 0.70
37.5 0.22
38.5 0.92
37 1.14
35.5 1.16
39 0.70
2.38
Acid detergent lignin
6.7 0.22
6.2 0.09
6.0 0.32
5.62 0.30
5.5 0.13
5.9 0.23
0.668
Crude protein
9.4 0.23
9.7 0.18
11.1 1.09
10 1.44
16.2 3.25
10.3 0.32
4.636
Inorganic ash
7.6 0.18
7.5 0.22
8.7 0.19
9.0 0.31
8.2 0.66
8.0 0.31
0.998
Organic matter
92.3 0.18
92.5 0.22
91.24 0.19
91.5 0.67
91.7 0.66
92 0.70
1.436
Dry matter digestibility
52.3 0.80
54.5 0.50
55.2 1.56
56.0 1.14
58.o 1.14
54.6 0.50
2.896
Dry organic matter digestibility
51 0.70
53 0.44
53.5 1.28
54.5 0.92
56.2 0.79
53 1.14
2.44
Cellulose(%) Hemicellulose(%) Lignin(%) LSD = least significant difference
33.5 26.3 6.7
31.5 27 6.2
32.5 26.6 8
31.4 25 5.6
29.65 23.45 5.5
33.2 25.5 5.9
2.36 3.00 0.92
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25
rate of 10 t ha 1 promotes the yield and nutritive value of this neglected grass species, particularly when combined with inorganic fertilisers.
20
References
15
AFIA, 2007. Australian Fodder Industry Association –laboratory method manual. Publication no. 03.001, ISBN 0642 58599 7, Victoria, Australia. Ball, D.M., Lacefield, G.D., Martin, N.P., Mertens, D.A., Olson, K.E., Putnam, D.H., Undersander, D.J., Wolf, M.W., 2001. Understanding Forage Quality. Park Ridge (IL). American Farm Bureau Federation; Publication 1-01. B. Fulkerson, 2007. Kikuyu grass. Technical note, Future dairy Australia. 2007 Hall, J.B., Seay, W.W., Baker, S.M., 2001. Nutrition and Feeding of the Cow-Calf herd: Production Cycle Nutrition and Nutrient Requirements of Cows, Pregnant Heifers and Bulls. Blacksburg (VA). Virginia Cooperative Extension; Publication 400-012. Hossain, M.K., Strezov, V., Chan, K.Y., Ziolkowski, A., Nelson, P.F., 2011. Influence of pyrolysis temperature on production and agronomic properties of wastewater sludge biochar. J. Environ. Manage. 92, 223–228. Hossain, M.K., Strezov, V., Chan, K.Y., Nelson, P.F., 2010. Agronomic properties of wastewater sludge biochar and bioavailability of metals in production of cherry tomato (Lycopersicon esculentum). Chemosphere 78, 1167–1171. Hossain, M.K., Strezov, V., Chan, K.Y., Nelson, P.F., 2009. Thermal characterisation of the products of wastewater sludge pyrolysis. J. Anal. Appl. Pyrolysis 85, 442– 446. Humphries, A.W., 1959. Hyparrhenia hirta– a promising pasture species. J. Aust. Inst. Agric. Sci. 4, 335–336. Isbell, R.F., 1996. The Australian Soil Classification. CSIRO Publishing, Collingwood, Australia. Junna, S., Bingchen, W., Gang, X., Hongbo, S., 2014. Effect of wheat straw biochar on carbon mineralization and guidance for large-scale soil quality improvement in the coastal wetland. Ecol. Eng. 62, 43–47. Kumar, S., Masto, R.E., Ram, L.C., Sarkar, P., George, J., Selvi, V.A., 2013. Biochar preparation from Parthenium hysterophorus and its potential use in soil application. Ecol. Eng. 55, 67–72. Marten, G.C., Andersen, R.N., 1975. Forage nutritive value and palatability of 12 common annual weeds. Crop Sci. 15, 821–827. McCormick, L.H., Lodge, G.M., McGufficke, B., 2002. Management for Coolatai Grass on the North West Slopes of NSW. NSW Agriculture, Dubbo and Orange. McCormick L.H., Lodge G.M., 1991. Coolatai grass-friend or foe? NSW Agriculture & Fisheries Agnote Reg. 2/015. Merkel, R.C., Pond, K.R., Burns, C.J., Fisher, D.S., 1999. Intake, digestibility and nitrogen utilization of three tropical tree legumes I. As sole feeds compared to Asystasia intrusa and Brachiaria brizantha. Anim. Feed Sci. Technol. 74, 15–28. Rogers, A.L., Anderson, G.W., Biddiscombe, E.F., Arkel, P., Glencross, R., Nicholas, D.A., Paterson, J.G., 1979. Perennial Pasture Grasses in South–Western Australia. 1. Preliminary Evaluation of Species. Department of Agriculture of Western Australia, Technical Bulletin No. 45. Rogers, A.L., Bailey, E.T., 1963. Salt tolerance trials with forage plants in south– western Australia. Aust. J. Exp. Agric. 3, 125–130 Anim. Husb. Strezov, V., Evans, T.J., Hayman, C., 2008. Thermal conversion of elephant grass (Pennisetum Purpureum Schum) to biogas, bio-oil and charcoal. Bioresour. Technol. 99, 8394–8399. Strezov, V., Moghtaderi, B., Lucas, J.A., 2003. Thermal study of decomposition of selected biomass. J. Therm. Anal. Calorim. 72, 1041–1048. Temme, D.G., Harvey, R.G., Fawcett, R.S., Young, A.W., 1979. Effects of annual weed control on alfalfa forage quality. Agron. J. 71, 51–54. Tothill, J.C., Hacker, J.B., 1983. The Grasses of Southern Queensland. University of Queensland Press, St. Lucia, Queensland. Underwood, A.J., Chapman, M.G., 2007. GMAV5 for Windows. Institute of Marine Ecology. University of Sydney, Australia. Ward, G.M., 1959. Effect of soil fertility upon the yield and nutritive value of forages– A review. J. Dairy Sci. 42, 277–297. Wheeler, D.J.B., Jacobs, S.W.L., Norton, B.E., 1982. Grasses of New South Wales. University of New England Publishing Unit, Armidale. Xu, G., Wei, L.L., Sun, J.N., Shao, H.B., Chang, S.X., 2013. What is more important for enhancing nutrient bioavailability with biochar application into a sandy soil: direct or indirect mechanism. Ecol. Eng. 52, 119–124.
Yield (g)
30
10 5 0 CP
SB
SS SBF Treatm ents
SSF
SF
Fig. 1. Coolatai grass yield per pot under different treatments.
the grass. Addition of sludge had close to neutral effect on the grass hemicellulose and lignin contents. 3.4. Yield Fig. 1 presents the yield of Coolatai grass under the six different treatments considered in this study. The average yield of control pot was only 11.3 g which is 20% less than the case of soil with biochar treatment. Biochar in combination with fertiliser (SBF) showed the highest effect on the yield of Coolatai grass followed by SSF and SF treatments. There is no significant difference in yield between the treatment SBF and SSF. The maximum average yield per pot was harvested from the combination of biochar with fertiliser (SBF) treatments (25.5 g) which is still 20% greater than the case of combination of sludge with fertiliser (SSF) and 89% above the yield produced in soil with biochar (SB) treatment. Yield is one of the most important parameters for cultivation of crops or grasses. The highest yield in the current work, achieved with the SBF treatment, was attributed to the additional nutrients mainly from the inorganic fertiliser and biochar. Biochar supplies nutrients and at the same time it improves the soil physical and chemical properties, which have positive impacts on the yield of production of crops. 4. Conclusion The effect of wastewater sludge and sludge biochar on cultivation of fast growing potential forage and energy crops was investigated in this work. The combined application of biochar and fertiliser had the most significant effect on the production yield of the grass with positive impact on some of the chemical parameters which improve its quality as a feed for livestock, such as metabolisable energy and crude protein content. The 20% yield increase was observed when biochar was applied alone largely due to the ability of wastewater sludge biochar to increase the nutrient availability. The results in the present study suggest that wastewater sludge biochar application to chromosol soils at a
Contents lists available at ScienceDirect
Ecological Engineering journal homepage: www.elsevier.com/locate/ecoleng
Short communication
Wastewater sludge and sludge biochar addition to soils for biomass production from Hyparrhenia hirta Mustafa K. Hossaina,b , Vladimir Strezova,* , Lester McCormickc , Peter F. Nelsona a
Department of Environmental Sciences, Faculty of Science and Engineering, Macquarie University, NSW 2109, Australia Elizabeth Macarthur Agricultural Institute, NSW Department of Primary Industries, Woodbridge Road, Menangle, NSW 2568, Australia c NSW Department of Primary Industries, 4 Marsden Park Road, Calala, NSW 2340, Australia b
A R T I C L E I N F O
A B S T R A C T
Article history: Received 3 February 2015 Received in revised form 15 April 2015 Accepted 23 May 2015 Available online xxx
The aim of the study was to determine the performance of sludge biochar compared to unprocessed wastewater sludge on production of Coolatai grass (Hyparrhenia hirta) as a potential forage and energy crop species. Pot trials were conducted to determine the nutritive quality and yield of Coolatai grass using chromosol soil amended with wastewater sludge and sludge biochar. The application of biochar combined with fertiliser was found to have the highest effect on the yield producing more than double of the plant dry matter comparing to unamended chromosol soil conditions. The combination of biochar and fertiliser treatment also increased some of the important chemical characteristics of Coolatai grass, such as the metabolisable energy and crude protein composition compared to control, wastewater sludge and fertiliser treatments. ã2015 Elsevier B.V. All rights reserved.
Keywords: Coolatai grass Wastewater sludge Biochar Nutritive value
1. Introduction Coolatai grass (Hyparrhenia hirta) was first introduced to the northern New South Wales, Australia from South Africa and the Mediterranean region in the 1940s. Since its introduction to Australia the grass has spread along roadside and grazing lands on many properties (McCormick et al., 2002). The grass is now available in the northern New South Wales (Wheeler et al., 1982) and in traprock soils of the southern Queensland (Tothill and Hacker, 1983). The plant grows well in warm season, it is extremely drought resistant (McCormick et al., 2002) but it is sensitive to frost in winter. Coolatai grass’ ideal growth conditions are between the temperatures of 30–40 C achieving growth of up to around 1 m in height. Coolatai grass is reported to have potential grass forage value (McCormick and Lodge, 1991). This grass is a valuable species at high stocking rates in Western Australia (Humphries, 1959; Rogers et al., 1979) and also can be cultivated under saline conditions (Rogers and Bailey, 1963), which may be useful to control the watertable and reduce soil salinity. Due to the fast growth rates and drought resistant condition requirements, Coolatai grass is potentially a target forage and energy crop species as it has potential to supplement the nutritional feed for animals during dry
* Corresponding author. Tel.: +61 2 9850 6959. E-mail address: [email protected] (V. Strezov). http://dx.doi.org/10.1016/j.ecoleng.2015.05.014 0925-8574/ ã 2015 Elsevier B.V. All rights reserved.
season or it can be used as biomass feedstock for energy production. However, production of fast growing crops as animal forage or as energy crops demands dedicated agricultural land and requires nutrients for cultivation. One of the options to alleviate these requirements is cultivation of fast growing crops in low quality soils using nutrient rich wastewater (sewage) sludge as a fertiliser. Biochars are carbon rich materials produced through pyrolysis of biomass, which are also potential nutrient supplying materials known to promote soil quality (Hossain et al., 2010), can be used to cultivate fast growing forage and energy crops and improve soil quality through ecological restoration (Xu et al., 2013). Biochar produced from wheat straw has been shown to reduce the carbon mineralisation rate in saline affected soils (Junna et al., 2014). The process of biochar production from wastes or weeds (Kumar et al., 2013) can also serve as an option for developing sustainable waste management and value adding strategy. In case of the wastewater sludge, however, it is still uncertain if the biochar produced from the sludge would perform more favourably in agricultural production of fast growing crops comparing to raw wastewater sludge application. The aim of this research is to investigate the effect of wastewater sludge and sludge biochar on the production of Coolatai grass and to evaluate the effect of soil amendment on the nutritional and energy value of this neglected pasture species. Biochar produced from wastewater sludge has been shown to promote production and growth of food crops while sequestering carbon and managing this waste more
346
M.K. Hossain et al. / Ecological Engineering 82 (2015) 345–348
effectively (Hossain et al., 2009, 2011). However, the effect of biochar on cultivation of energy and forage crops has still not been assessed. This study was designed to determine the variations of different nutrient levels, dry matter production and energy value of Coolatai grass cultivated in a soil amended with wastewater sludge, which is a by-product of the wastewater treatment industry, and sludge biochar which is produced through a volume reducing pyrolysis process of the wastewater sludge. 2. Materials and methods
pot with a size of 19 cm in height, 15 cm in diameter at the bottom and 20 cm in diameter at the top. 2.4. Chemical composition analysis At the end of the 11 weeks pot trial experiments the plants were harvested from each pot and oven dried at 80 C to constant weight to determine the dry matter production. The samples were then ground to 0.8 mm particle size and analysed for chemical composition in a Bruker MPA FTIR following the analytical method described by AFIA, 2007.
2.1. Soil 2.5. Statistical analysis A composite soil sample was collected 0.1 m of the top soil layer from the paddock of Centre for Recycled Organic Agriculture (CROA) site near Camden, south west of Sydney. According to the Australian soil classification the soil used for this study is chromosol (Isbell, 1996). The agricultural properties of the soil are shown in Table 1. The soil was found to be low in total nitrogen (0.13%), while the ammonium nitrogen was 3.6 mg kg 1 and phosphorus was 15 mg kg 1. The soil was acidic in nature.
One way analysis of variance and post-hoc Student-NewmansKules (SNK) test was performed using GMAV5 (Underwood and Chapman, 2007) to determine the significance of differences of the values of chemical composition of Coolatai grass grown with wastewater sludge and sludge biochar. The variation and reproducibility of the data were tested using the Cochran’s test. 3. Results and discussion
2.2. Wastewater sludge and biochar production 3.1. Proximate and ultimate analysis The wastewater sludge was collected from an urban wastewater treatment plant in Sydney. Some of the chemical properties of the sludge are shown in Table 1. The sludge sample is found to be high in ammonium nitrogen (7275 mg kg 1), low in nitrate nitrogen (35 mg kg 1) and acidic in nature. The biochar was produced through pyrolysis using a fixed bed reactor at a temperature of 550 C and heating rate of 10 C mim 1. The agronomic properties of the wastewater sludge biochar are shown in Table 1. The biochar was found to be alkaline in nature, low in total N (2.3%) and high in phosphorus (1100 mg kg 1). 2.3. Pot experiments Coolatai grass (Hyparrhenia hirta) sample was collected from Tamworth, northern part of New South Wales as a target species to carry out the pot trial experiments. The experiments were conducted under a temperature controlled (30–35 C) glass house conditions. The experimental design was factorial randomised block design with six treatments (i) control (CP) (ii) soil with wastewater sludge (SS) (iii) soil with wastewater sludge biochar (SB) (iv) soil with wastewater sludge and fertiliser (SSF) (v) soil with wastewater sludge biochar and fertiliser (SBF) and (vi) soil with fertiliser (SF). Each treatment was carried out in five replicates. The application rate of sludge and biochar was 10 t ha 1. There is no recommend rate of fertiliser application for cultivation of Coolatai grass. The fertiliser application used in the current study was equivalent to 120 kg ha 1 of nitrogen; 70 kg ha 1 of phosphorus and 80 kg ha 1 of potassium based on previous investigation conducted by Hossain et al. (2010) who demonstrated benefits to soil and plants by the similar fertiliser application rate. Six kg of air dried soil was packed in each cylindrical plastic Table 1 Agricultural properties of soil, wastewater sludge and sludge biochar used in the pot experiments.
The main physical and chemical characteristics of Coolatai grass are given in Table 2. With 5.6% ash content, the grass was found to have higher ash composition than most woody biomass species (Strezov et al., 2003), which are in the order of 0.2–0.3% and was higher than some grass species, such as elephant grass, which was reported to have ash content of approximately 3% (Strezov et al., 2008). The fixed carbon content was in the same order as wood and grass species measured previously, while the volatile matter was somewhat lower. Consequently, the calorific value of the Coolatai grass, estimated with a bomb calorimeter at 16.9 MJ/kg, is slightly lower than the woody and grass species determined previously. 3.2. Metabolisable energy Metabolisable energy of forage is the vital limiting nutrient for animals in a pasture based system and maximised energy density of the pasture feed is important for growth and healthy body function of the livestock. The metabolisable energy values of Coolatai grass under the prescribed treatment conditions are given in Table 2. There is a significant difference of metabolisable energy in the Coolatai grass cultivated under SF, SS and CP treatments comparing with SBF treatment. The highest metabolisable energy was found in the SBF treatment (8.4%) followed by SSF (8%) and SB (7.9%) treatment conditions. The lowest metabolisable energy content was detected in the control (CP) treatment (7.3%). These
Table 2 Proximate, ultimate analysis and calorific value of Coolatai grass. Proximate analysis Moisture % Ash % 7.5 5.6
Properties
Unit
Soil
Wastewater sludge
Biochar
Ultimate analysis Carbon% Hydrogen% 42.6 5.38
EC pH (CaCl2) Total N P (Colwell) Ammonium N (KCL extract) Nitrate N (KCL extract)
dS m-1 pH unit % mg kg 1 mg kg 1 mg kg 1
0.09 4.6 0.13 15 3.6 4.9
11.9 4.4 3.3 747 7275 35
1.9 8.2 2.3 1100 11 0.49
Metabolisable energy (MJ/kg DM) CP SS 7.3 7.7 0.21 0.08 Calorific value (ML/kg) 16.9 Least Significant difference (LSD) = 0.59
Nitrogen% 1.7
Volatile matter% 69.4
Fixed carbon% 17.5
Sulphur% 0.23
Oxygen% 37
SB 7.9 0.26
SSF 8.0 0.17
SSF 8.4 0.18
SF 7.6 0.23
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findings highlight that the combined effect of biochar and fertiliser used for the SBF treatment maximises the metabolisable energy availability in Coolatai grass. The results presented here are within similar range to the metabolisable energy measured previously in the leaf of kikuyu grass at 9.2% and in the stem measured at 7.4% (Fulkerson, 2007). 3.3. Chemical composition The effect of treatment conditions on the chemical composition of Coolatai grass is shown in Table 3. The biochar was found to significantly increase the crude protein content in the grass in both treatments with and without fertiliser (SBF and SB). The crude protein content of SBF treatment significantly varied with all other treatments. Protein is a vital parameter for all livestock diets but the required amount varies between animals. For instance, the required crude protein for mature beef cows is 10.5% (Hall et al., 2001), which was achieved in case of SB and SBF treatments. On the other hand the required crude protein for young goats is 14% and this amount was measured only with the grass produced for the combined fertiliser with biochar (SBF) treatment. It appears that in case of all treatments where biochar was not applied, including fertiliser treatment, the crude protein content of the Coolatai plant does not meet the minimum requirements as a feed for livestock. Application of wastewater sludge biochar increased the amount of crude protein of Coolatai grass possibly because the biochar contains bioavailable nitrogen and phosphorus, which are directly involved as protein and nucleic acid forming constituents (Ward, 1959). Neutral detergent fibre, acid detergent fibre and acid detergent lignin in Coolatai grass decreased in the case of biochar, sludge and the fertiliser treatments, while increasing its dry matter and dry organic matter digestibility comparing to control treatment. The neutral detergent fibre (NDF) of the plant is a measure used to predict intake potential of the plant by livestock (Ball et al., 2001). In the results shown in Table 3 the highest NDF was detected for the control pot conditions (66.9%), while the lowest was
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determined for the SBF treatment (60.2%) conditions. The SBF treatment significantly decreased the NDF of the grass compared to the control treatment. The lowest NDF value measured for the case of SBF treatment is still well above the NDF values reported for smooth brome grass and quackgrass at 56% (Marten and Andersen, 1975). The acid detergent fibre (ADF) concentration in the plants is a parameter used to determine digestibility of a plant. In the case of this study the control treatment conditions (CP) produced plants with the highest ADF (40%) concentration followed by SF, SB, SS, SSF treatment conditions. The SBF treatment was found to produce grass with the lowest ADF concentration at 35%, however this concentration is still well above the reported ADF values for other plants, such as giant foxtail (33%), yellow foxtail (30%) (Marten and Andersen, 1975) and alfalfa forage at early bloom (23%) (Temme et al., 1979). Hence, addition of biochar, sludge and fertiliser will have no significant adverse impact on the quality of the intake potential and digestibility of the plant. Cellulose, hemicellulose and lignin content of Coolatai grass are shown in Table 3. These parameters are important as cellulose and hemicellulose in forage are the main sources of energy to ruminants (Merkel et al., 1999). There is no significant difference in cellulose content among the treatments compared to control except the SBF treatment. SBF treatment showed significant difference of the cellulose content within the treatments. In this work, addition of biochar and sludge to the soil with and without fertiliser, decreased the cellulose content of Coolatai grass. As discussed by Ward (1959) the chemical composition of forage may be altered through the use of fertilisers and it is very likely that the addition of nutrients through the biochar and sludge in the current work may have reduced the amount of cellulose in the grass. The highest hemicellulose content was in the grass cultivated under the SS treatment which is significantly different to the SBF treatment. The highest lignin content was in the SB treatment, which showed significant difference to the control and all other treatments. The biochar addition to soil was also found to increase the lignin and have neutral effect on the hemicellulose content of
Table 3 Chemical composition of Coolatai grass. Parameters (%) Neutral detergent fibre
CP 66.9 0.40
SS 64.8 0.86
SB 65.8 1.68
SSF 62 2.25
SBF 60.2 2.88
SF 65.0 1.41
LSD 5.01
Acid detergent fibre
40 0.70
37.5 0.22
38.5 0.92
37 1.14
35.5 1.16
39 0.70
2.38
Acid detergent lignin
6.7 0.22
6.2 0.09
6.0 0.32
5.62 0.30
5.5 0.13
5.9 0.23
0.668
Crude protein
9.4 0.23
9.7 0.18
11.1 1.09
10 1.44
16.2 3.25
10.3 0.32
4.636
Inorganic ash
7.6 0.18
7.5 0.22
8.7 0.19
9.0 0.31
8.2 0.66
8.0 0.31
0.998
Organic matter
92.3 0.18
92.5 0.22
91.24 0.19
91.5 0.67
91.7 0.66
92 0.70
1.436
Dry matter digestibility
52.3 0.80
54.5 0.50
55.2 1.56
56.0 1.14
58.o 1.14
54.6 0.50
2.896
Dry organic matter digestibility
51 0.70
53 0.44
53.5 1.28
54.5 0.92
56.2 0.79
53 1.14
2.44
Cellulose(%) Hemicellulose(%) Lignin(%) LSD = least significant difference
33.5 26.3 6.7
31.5 27 6.2
32.5 26.6 8
31.4 25 5.6
29.65 23.45 5.5
33.2 25.5 5.9
2.36 3.00 0.92
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rate of 10 t ha 1 promotes the yield and nutritive value of this neglected grass species, particularly when combined with inorganic fertilisers.
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References
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AFIA, 2007. Australian Fodder Industry Association –laboratory method manual. Publication no. 03.001, ISBN 0642 58599 7, Victoria, Australia. Ball, D.M., Lacefield, G.D., Martin, N.P., Mertens, D.A., Olson, K.E., Putnam, D.H., Undersander, D.J., Wolf, M.W., 2001. Understanding Forage Quality. Park Ridge (IL). American Farm Bureau Federation; Publication 1-01. B. Fulkerson, 2007. Kikuyu grass. Technical note, Future dairy Australia. 2007 Hall, J.B., Seay, W.W., Baker, S.M., 2001. Nutrition and Feeding of the Cow-Calf herd: Production Cycle Nutrition and Nutrient Requirements of Cows, Pregnant Heifers and Bulls. Blacksburg (VA). Virginia Cooperative Extension; Publication 400-012. Hossain, M.K., Strezov, V., Chan, K.Y., Ziolkowski, A., Nelson, P.F., 2011. Influence of pyrolysis temperature on production and agronomic properties of wastewater sludge biochar. J. Environ. Manage. 92, 223–228. Hossain, M.K., Strezov, V., Chan, K.Y., Nelson, P.F., 2010. Agronomic properties of wastewater sludge biochar and bioavailability of metals in production of cherry tomato (Lycopersicon esculentum). Chemosphere 78, 1167–1171. Hossain, M.K., Strezov, V., Chan, K.Y., Nelson, P.F., 2009. Thermal characterisation of the products of wastewater sludge pyrolysis. J. Anal. Appl. Pyrolysis 85, 442– 446. Humphries, A.W., 1959. Hyparrhenia hirta– a promising pasture species. J. Aust. Inst. Agric. Sci. 4, 335–336. Isbell, R.F., 1996. The Australian Soil Classification. CSIRO Publishing, Collingwood, Australia. Junna, S., Bingchen, W., Gang, X., Hongbo, S., 2014. Effect of wheat straw biochar on carbon mineralization and guidance for large-scale soil quality improvement in the coastal wetland. Ecol. Eng. 62, 43–47. Kumar, S., Masto, R.E., Ram, L.C., Sarkar, P., George, J., Selvi, V.A., 2013. Biochar preparation from Parthenium hysterophorus and its potential use in soil application. Ecol. Eng. 55, 67–72. Marten, G.C., Andersen, R.N., 1975. Forage nutritive value and palatability of 12 common annual weeds. Crop Sci. 15, 821–827. McCormick, L.H., Lodge, G.M., McGufficke, B., 2002. Management for Coolatai Grass on the North West Slopes of NSW. NSW Agriculture, Dubbo and Orange. McCormick L.H., Lodge G.M., 1991. Coolatai grass-friend or foe? NSW Agriculture & Fisheries Agnote Reg. 2/015. Merkel, R.C., Pond, K.R., Burns, C.J., Fisher, D.S., 1999. Intake, digestibility and nitrogen utilization of three tropical tree legumes I. As sole feeds compared to Asystasia intrusa and Brachiaria brizantha. Anim. Feed Sci. Technol. 74, 15–28. Rogers, A.L., Anderson, G.W., Biddiscombe, E.F., Arkel, P., Glencross, R., Nicholas, D.A., Paterson, J.G., 1979. Perennial Pasture Grasses in South–Western Australia. 1. Preliminary Evaluation of Species. Department of Agriculture of Western Australia, Technical Bulletin No. 45. Rogers, A.L., Bailey, E.T., 1963. Salt tolerance trials with forage plants in south– western Australia. Aust. J. Exp. Agric. 3, 125–130 Anim. Husb. Strezov, V., Evans, T.J., Hayman, C., 2008. Thermal conversion of elephant grass (Pennisetum Purpureum Schum) to biogas, bio-oil and charcoal. Bioresour. Technol. 99, 8394–8399. Strezov, V., Moghtaderi, B., Lucas, J.A., 2003. Thermal study of decomposition of selected biomass. J. Therm. Anal. Calorim. 72, 1041–1048. Temme, D.G., Harvey, R.G., Fawcett, R.S., Young, A.W., 1979. Effects of annual weed control on alfalfa forage quality. Agron. J. 71, 51–54. Tothill, J.C., Hacker, J.B., 1983. The Grasses of Southern Queensland. University of Queensland Press, St. Lucia, Queensland. Underwood, A.J., Chapman, M.G., 2007. GMAV5 for Windows. Institute of Marine Ecology. University of Sydney, Australia. Ward, G.M., 1959. Effect of soil fertility upon the yield and nutritive value of forages– A review. J. Dairy Sci. 42, 277–297. Wheeler, D.J.B., Jacobs, S.W.L., Norton, B.E., 1982. Grasses of New South Wales. University of New England Publishing Unit, Armidale. Xu, G., Wei, L.L., Sun, J.N., Shao, H.B., Chang, S.X., 2013. What is more important for enhancing nutrient bioavailability with biochar application into a sandy soil: direct or indirect mechanism. Ecol. Eng. 52, 119–124.
Yield (g)
30
10 5 0 CP
SB
SS SBF Treatm ents
SSF
SF
Fig. 1. Coolatai grass yield per pot under different treatments.
the grass. Addition of sludge had close to neutral effect on the grass hemicellulose and lignin contents. 3.4. Yield Fig. 1 presents the yield of Coolatai grass under the six different treatments considered in this study. The average yield of control pot was only 11.3 g which is 20% less than the case of soil with biochar treatment. Biochar in combination with fertiliser (SBF) showed the highest effect on the yield of Coolatai grass followed by SSF and SF treatments. There is no significant difference in yield between the treatment SBF and SSF. The maximum average yield per pot was harvested from the combination of biochar with fertiliser (SBF) treatments (25.5 g) which is still 20% greater than the case of combination of sludge with fertiliser (SSF) and 89% above the yield produced in soil with biochar (SB) treatment. Yield is one of the most important parameters for cultivation of crops or grasses. The highest yield in the current work, achieved with the SBF treatment, was attributed to the additional nutrients mainly from the inorganic fertiliser and biochar. Biochar supplies nutrients and at the same time it improves the soil physical and chemical properties, which have positive impacts on the yield of production of crops. 4. Conclusion The effect of wastewater sludge and sludge biochar on cultivation of fast growing potential forage and energy crops was investigated in this work. The combined application of biochar and fertiliser had the most significant effect on the production yield of the grass with positive impact on some of the chemical parameters which improve its quality as a feed for livestock, such as metabolisable energy and crude protein content. The 20% yield increase was observed when biochar was applied alone largely due to the ability of wastewater sludge biochar to increase the nutrient availability. The results in the present study suggest that wastewater sludge biochar application to chromosol soils at a