Humification of poultry waste and rice husk using additives and its application
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Abstract
Purpose
The purpose of this study was to assess the efficacy of inorganic additives during the humification of poultry waste and rice husk.
Methods
Poultry waste mixture was treated with aluminum sulfate 3% and rock phosphate 2% during co-composting of mixture in mechanical composter and evaluated the potential of humification and compost nitrogen mineralization in incubation and pot study.
Results
The mesophilic to thermophilic phase of composting mixture is prolonged due to the rise in temperature, pH and ammonia that steadily decrease near the maturation phase. The humification rate (HR), humification index (HI), degree of polymerization (DP) and cation exchange capacity (CEC) increased in enriched compost as compared to unenriched with the composting process. The germination index (GI) of enriched compost (C/N:10.8) was significantly greater than unenriched compost (C/N:23.43). These all maturity indices, i.e., C/N, CE, HI, DP, HR revealed the significant correlation with each other. In the incubation study, nitrogen mineralization was also evaluated and nitrogen was applied at the rate of 50 kg-N/ha using the enriched and unenriched compost and found high mineralization in enriched compost due to low C/N. A laboratory-scale pot experiment was also conducted, applied the compost at a rate of 100 kg-N/ha and recorded the encouraging results in growth and nutrition value of Abelmoschus esculentus plant.
Conclusion
It was concluded that use of additives have a significant impact on humification of poultry waste.
Keywords
Compost Enrichment Experiment Mixing HumificationIntroduction
In Pakistan, there are several poultry farms that produce a large amount of poultry waste daily and all poultry farms’ owners are facing problems due to lack of storage, disposal and handling facilities. Problems related to regulatory pressure, urban invasion, fly control, and proximate land base for waste disposal compel the search for an alternative waste management system (Yadav et al. 2017). The commonly used livestock solid waste disposal techniques include on-site burial, landfill, incineration and composting. However, its direct use for plantations, pastures and open field’s area reduced the variety, quality and can disrupt the biological structure of the soil. Poultry waste is a mixture of poultry feces, bedding material, waste feed and feathers that have an important financial and viable potential for composting. The selection of the composting process depends upon the climate condition, nature of waste, type of animal waste, economic conditions and its application. The aerobic and anaerobic composting process are commonly used for poultry waste decomposition and are better compared to burning and other different drying techniques (Chen and Jiang 2014). The microbiological, chemical processed and recycled chicken feces waste are significantly used as organic fertilizer and widely spread on productive land. Poultry waste contains different concentrations of water and nutrients for plants’ growth like calcium, boron, phosphorus, potassium, magnesium, manganese, copper, nitrogen, sulfur, zinc, iron, molybdenum and organic matter. It is easily available at low cost from vicinity farms to restore and improve the chemical, physical and biological fertility of the degraded soil (Liang et al. 2017; Yee 2017).
However, the fresh poultry waste may contain an inappropriate C/N ratio, pathogens, an improper amount of plant nutrients, annoying odors and its application may slow down the germination of seed, lessen the growth of plant and harm the crops by rivaling for oxygen or may cause phytotoxicity to plants due to scarcity in organic matter (Chaudhry et al. 2013). Due to these concerns, the demand for humification and high cost of synthetic fertilizer, farmers prefer to adopt the organic farming techniques. Composting is a low investment technology that can transform organic waste into valuable organic matter through bio-oxidation which enhances the quality of soil for plant growth by augmenting aeration, water status, micro- and macronutrients. The compost production in Pakistan is of low quality for plants and its efficiency is also extremely poor. Therefore, it is the need of the hour to enrich the poultry waste materials for maximum nutrient availability to plants and reduce the time of humification through microbial activity. An extensive literature survey was conducted and it was found that many scientists have studied the impact of enrichment on a variety of wastes and found encouraging results during humification, nutrients’ dynamic, plant toxicity and humification/decomposition time. They used ash, lime, rock phosphate, ferrous sulfate, calcium hydroxide and peroxide (Nishanth and Biswas 2008; Himanen and Hannieen 2009; Iqbal et al. 2010, 2015, 2016; Yadav et al. 2017). Moreover, composting of poultry waste in Pakistan is currently not conducted scientifically by private contractors, where it takes 4 months to produce compost for use and their humification quality is still ambiguous. Therefore, the present study was conducted to examine the influence of aluminum sulfate and rock phosphate on poultry waste humification and uptake of compost nutrients by Abelmoschus esculentus (ladyfinger) plants in pot and incubation study.
Materials and methods
Poultry waste was collected from Raiwind poultry farm, Lahore and taken to the composting plant at PCSIR laboratories complex in Lahore. Rice husk was purchased from the local market and was used to reduce the moisture of poultry waste. Rice husk was added in poultry waste at the rate of 30% to adjust the moisture content of mixture for composting. Poultry waste and rice husk was blended in mechanical composter of 10 L capacity. The drum of composter is the main unit which is of 300 mm length and 250 mm diameter and is made up of a 3 mm thick sheet of stainless steel. The drum was griped on an iron metal stand and the inner side of the composter is made of stainless steel (SS) and the steel angles were welded horizontally for complete mixing of waste. Simultaneously, two holes, one which was 200 mm in size and the other 100 mm, were made on drum both at the upper and the lower portion, respectively. The poultry waste and rice husk mixture was loaded into the composter manually and filled up to fifty percent of the entire volume. The composter runs frequently 5 h daily at 500 RPM which was adjusted by the electrical gearbox and the temperature of mixture was monitored during this period. Aluminum sulfate (3%) and rock phosphate (2%) were used as inorganic additives, that were spread on the mixture [poultry waste (70%) and rice husk (30%)] and mixed in a mechanical composter in an experimental batch (enriched). In a similar manner but without additives, the unenriched compost was run and analyzed with the same parameters. Each batch was done in triplicates and their results were reported as an average. The 300 gm samples were collected from each run after every five days regularly up to 60 days. Samples were dried at 75 °C and passed through a sieve of 2 mm to examine the pattern of HI, DP, ash, C/N ratio and HR.
Nitrogen mineralization
The sandy clay loam soil (BD: 50.43 kgm3) 300 g was kept in a plastic container (diameter: 5 cm) to study the N-mineralization of both types of compost under the incubation process. The air-dried soil (size: 2 mm) was kept at 50% moisture by the addition of demineralized water and was incubated for 7 days to optimize the condition of soil at a constant temperature of 20 °C. On area basis, the unenriched and enriched composts were applied at the rate of 50 kg-N/ha to each pot and then deionized water was added and the mixture was mixed regularly after a 5-day interval to minimize denitrification. Pots were incubated in a growth chamber at 25 °C and nitrogen mineralization rate (NMR) was calculated in a similar manner to our previous study (Iqbal et al. 2010).
Pot experiment
The ladyfinger seeds were planted in pots (diameter 20.0 cm and height 20.0 cm) under controlled laboratory conditions and the pots were filled at the rate of 5 kg soil/pot with air-dried sandy clay loam soil (2 mm) and two seeds were permitted to grow in each pot. The pots were arranged as a randomized absolute block design with three treatments, C1 (enriched compost), C2 (unenriched compost) and C3 (control soil) and three replicates were practically performed at the rate of 100 kg-N/ha. P and K were applied at a rate of 50 kg/ha using single super phosphate and potassium according to the need of crop. Canal water was used to irrigate the soil and the quality of water [electrical conductivity (EC) 0.0.05 μs/cm, sodium absorption ratio (SAR), 0.3 m mole/l] was in accordance with the requirement of crop.
Analytical methods
The chemical properties of compost, poultry waste, rice husk and soil micronutrients like EC, N, P,K, Ash, OM, Zn, Mn, Pb, Cu were evaluated using the ASTM method. The total amount of N and total C in compost/soil was carried out by catalytic tube combustion using the Vario Macro elementar CHNS analyzer (S.N:11046079). The C/N ratio was calculated as the quotient of total carbon over total nitrogen. Phytotoxicity and particle size procedure was adopted similar to our last study (Iqbal et al. 2014).
Statistical analysis
The compost and poultry waste were analyzed three times and the results were reported as an average with standard deviation using Microsoft 2010. The Pearson correlation was also determined between compost parameters FA, HA, DP, HI, C/N and HR with SPSS.19.
Results and discussion
pH of compost
Effect of enrichment on humification parameters. a pH and C/N, b temperature, c CEC and HR, d HI and HR, e GI. Enrichment of aluminum sulfate 3%, and rock phosphate 2% on co-composting of poultry waste and rice husk. All results are based on three observations and their S.D (± 3) is also reported
Temperature of the compost
Temperature is the live indication of microbial activity occurring during the composting process. It helps to monitor the performance and rate of humification in the composting matrix. It has a dynamic part in succession and evaluation of microbiological communities in the entire biological process. It promotes the degradation of complex substrate into simpler compounds (Waqas et al. 2017). The temperature of the decaying waste increased quickly as composting preceded; however, temperature decreased slowly after the thermophilic stage and became stable (Iqbal et al. 2014). In this current study, the temperature was recorded daily over the entire composting process but was reported at 5-day intervals. In the enriched compost, the temperature was raised rapidly in first 20 days which subsequently exhibited the decline in their temperature. It means the humification of composting matrix was higher than the unenriched compost. Temperature peak for unenriched compost revealed that the humification rate is much slow than the enriched compost due to the addition of inorganic additive which promoted the decomposition or humification of enriched compost (Fig. 1b). Moreover, the temperature of enriched compost and ambient was not significantly different at the end of composting process. Composting phenomena is primarily based on moisture and aeration, which regulate the mineralization of organic materials. When mineralization of composting matrix attained a peak, then the temperature of decomposed material shifted to ambient temperature, the material became soft, finer, and dark brown in color, no malodors were detected and C/N became stable. It means the composting matrix revealed the completion of humification process and compost maturity (Chaudhry et al. 2013).
C/N ratio of compost
It is the reflection of organic matter (OM) decomposition and its increase is a positive sign of humification. Present study results depicted that with the rise of composting time there is a fall in carbon and nitrogen ratio in enriched and unenriched composts. The bio-oxidation of carbon into carbon dioxide is due to the impact of rock phosphate and other inorganic additives in early stage of composting. C/N data elucidated that it did not show variation in first 15 days in both composts, later on it decreased rapidly and became stable on 35th day of composting process in enriched compost and was 57.9% less C/N than unenriched compost (Fig. 1a). There was a great significant difference was found in C/N at the end of the experiment between enriched (C/N:10.61) and unenriched compost (C/N:23.13). According to Golueke (1981) below 20 the carbon nitrogen ratio showed the adequate maturity and C/N of 15 or minimum of this is preferable. The present findings were also coherent with many scientists’ results (Saidi et al. 2008; Iqbal et al. 2010). The nitrate and ammonia reduction data were also collected but presently not reported here.
Organic matter and ash of compost
Chemical characteristics of poultry waste, enriched, unenriched compost and rice husk
Parameters | Poultry waste | Enriched compost | Unenriched compost | Rice husk |
---|---|---|---|---|
Moisture (%) | 60.8 | 26.43 | 34.98 | 9.43 |
pH | 8.39 | 8.65 | 8.21 | 5.12 |
Ash (%) | 47.67 | 59.20 | 52.08 | 65.97 |
Organic matter (%) | 52.33 | 40.8 | 47.92 | 34.03 |
Total nitrogen (%) | 4.02 | 6.21 | 4.19 | 0.69 |
Total carbon (%) | 122.9 | 67.56 | 98.21 | 20.43 |
C/N ratio | 30.4 | 10.8 | 23.43 | 29.61 |
Total P (%) | 1.5 | 2.09 | 1.43 | 0.11 |
Total K (%) | 1.97 | 2.05 | 2.02 | 0.03 |
Total sulfur (%) | 0.32 | 0.13 | 0.25 | 0.41 |
Total hydrogen (%) | 6.71 | 2.93 | 3.88 | 1.04 |
Zn (mg/kg) | 32.13 | 19.82 | 22.30 | 0.01 |
Pb (mg/kg) | 0.90 | 0.56 | 0.1 | 0.00 |
Mn (mg/kg) | 1.39 | 1.11 | 1.24 | 0.01 |
Cu (mg/kg) | 0.51 | 0.45 | 0.43 | 0.02 |
Humification of compost
Pearson’s correlation between chemical characteristics of enriched compost
DP | HR | CEC | C/N | HI | |
---|---|---|---|---|---|
DP | 1 | 0.99** | 0.99** | − 0.96** | 0.97** |
HR | 1 | 0.99** | − 0.95** | 0.98* | |
CEC | 1 | − 0.96** | 0.98* | ||
C/N | 1 | − 0.96** | |||
HI | 1 |
Minerals in soil that are negatively charged attract and retained cations like calcium (Ca), potassium (K), magnesium (Mg) and sodium (Na). The CEC is a reversible process that holds these nutrients from leaching and then releases them for crop at a mature humified phase. CEC during composting increased gradually and after 65 days both unenriched and enriched compost exhibited no significant difference in their values, whereas the enriched compost’s results revealed the maximum values at 35th day of composting and it was 58% more than the unenriched compost (Fig. 1c). These results depicted the impact of enrichment on humification of poultry waste. Conversion of lingo-cellulose into humus by microbes may cause the enhancement in CEC. When the temperature of compost became equal to the ambient temperature, humification lead to the formation of humic compounds during polymerization reaction. These results are also in line with Iqbal et al. (2010) that used ferrous sulfate and rock phosphate for the decay of the MSW. Formation of humic substances depends on the OM in which humification and polymerization have taken place.
The humic acid concentration increased during the process, whereas fulvic acid (FA) increased initially and later on decreased throughout the process.
The variation of humification index (HI) and degree of polymerization (DP) with time during the humification of poultry waste is shown in Fig. 1d. Both the humification parameters HI and DP increased in the composting process. HI improved its concentration to 66% and 73.5% in unenriched and enriched compost at the end of the composting in comparison to the fifth day. The same observations were recorded in the case of DP and there was no particular disparity in their net results. The increasing pattern in both parameters specify an increase in the structural complexity of the humic substances, similarly due to a lower proportion of more easily degradable substances, which would be incorporated in the FA fraction. As regards to humification rate, it increased steadily during the composting like CEC and HI and DP.
Stability and maturity of the compost
It can be gauged by phytotoxicity. It was caused by an increase in the concentration of toxic substances like ammonia, phenolic compounds and heavy metals. Germination Index (GI) is the test used to confirm the maturity of compost that has no phytotoxic compounds or heavy metals that hamper the growth of the plants. The immature compost’s phytotoxicity depends upon the composting methodology, maturation time, phenolic compounds and the nature of the stock material. The enriched and unenriched samples of the compost were collected at different days of composting such as on 15th, 30th, 45th and 65th day and their germination test results were reported in Fig. 1e. The germination index percentage depicted a low range of 45% and 68% on the 15th day of composting in enriched and unenriched composts, respectively, whereas 34% GI was seen in enriched compost than the unenriched one. It depicted that the decomposition or humification process was in initial stage and all organic acids and ammonia production was slow. Both composts behaved in a positive trend up to 93 and 99%, respectively, at the end of composting. According to Zucconi et al. (1981), when GI of any compost is 80%, then there is no sign of phytotoxicity. Moreover, both composts had obtained more than 80% germination index on the 45th day of humification. The results of present study were also in line with many other researchers (Aboukila et al. 2016; Himanen and Hanninen 2009; Iqbal et al. 2014).
N-mineralization of compost
Effect of enrichment on mineralization of nitrogen
Pot study
Effect of enriched, unenriched compost and control on characteristics of plants
Parameters | C1 | C2 | C3 |
---|---|---|---|
Root length (cm) | 54.9a | 46.2b | 33.6c |
Root dry weight (gm/Pot) | 21.5a | 16.3b,c | 11.9c |
No of fruits/pot | 33b | 27b | 9c |
Fresh fruit weight/pot (g/pot) | 86b | 83b | 65c |
Stem height (cm) | 138b | 123a | 98c |
Stem girth (cm) | 29b | 27b,c | 24c |
DM/plant (gm) | 13.8b | 11.01b,c | 8.3c |
Effect of treatments on nutrient uptake by plant and soil
Treatments | Plant | Soil | ||||
---|---|---|---|---|---|---|
Nitrogen (g/plant) | Potassium (g/plant) | Phosphate (g/plant) | Nitrogen (g/kg) | Potassium (g/kg) | Phosphate (g/kg) | |
C1 | 2.15 | 1.01 | 0.76 | 2.32 | 1.15 | 1.09 |
C2 | 1.21 | 0.81 | 0.14 | 1.63 | 0.95 | 0.43 |
C3 | 0.13 | 0.01 | 0.001 | 0.17 | 0.02 | 0.01 |
Conclusion
The application of inorganic additives in the mechanical co-composting of poultry waste and rice husk lessens the humification period and C/N ratio, which enhanced the nitrogen mineralization. Pearson correlation validates the humification process parameters. The application of enriched compost in pot study of ladyfinger plant perks up the phytochemical properties than unenriched compost due to the humification angle. The present study’s formulation can be applied on various wastes to enhance the humification process to ultimately reduce the decomposition time.
Notes
References
- Aboukila EF, Nassar IN, Rashad M, Hafez M, Norton JB (2016) Reclamation of calcareous soil and improvement of squash growth using brewers’ spent grain and compost. J Saudi Soci Agric Sci 1–8. https://www.nimss.org/projects/view/publications/17136
- Aparna C, Saritha P, Himabindu Anjaneyulu Y (2008) Techniques for the evaluation of maturity for composts of industrially contaminated lake sediments. Waste Manag 28:1773–1784CrossRefGoogle Scholar
- Banu JR, Do KU, Yeom IT (2008) Effect of ferrous sulphate on nitrification during simultaneous phosphorus removal from domestic wastewater using a laboratory scale anoxic/oxic reactor. World J Microbiol Biotech 24:2981–2986CrossRefGoogle Scholar
- Banu JR, Khac-Uan D, Kaliappan S, Ick-Tae Y (2009) Effect of alum on nitrification during simultaneous phosphorous removal in anoxic/oxic reactor. Biotech Bioproc Eng 14:543–548. https://doi.org/10.1007/s12257-008-0279-x CrossRefGoogle Scholar
- Cardenas E, Gabriel Gasco A, Paz-Ferreiro J (2017) The effect of biochar and compost from urban organic waste on plant biomass and properties of an artificially copper polluted soil. Int Biodeterior Biodegrad 124:223–232CrossRefGoogle Scholar
- Chaudhry AN, Naeem MA, Jilani G, Razzaq A, Zhang DM, Azeem M, Ahmed M, Ghaudhry (2013) Influence of composting and poultry litter storage methods on mineralization and nutrient dynamic. J Anim Plant Sci 23(2):500–506Google Scholar
- Chen Z, Jiang X (2014) Microbiological safety of chicken litter or chicken litter-based organic fertilizers. Rev Agric 4:1–29. https://doi.org/10.3390/agriculture4010001 CrossRefGoogle Scholar
- Do KU, Banu JR, Kaliappan S, Ick-Tae Y (2013) Influence of the thermochemical sludge pretreatment on the nitrification of A/O reactor with the removal of phosphorus by simultaneous precipitation. Biotech Bioproc Eng 18:313–320. https://doi.org/10.1007/s12257-012-0492-5 CrossRefGoogle Scholar
- Golueke CG (1981) Principles of biological resources recovery. Bio Cycle 22:36–40Google Scholar
- Hanninen M, Himanen K (2009) Effect of commercial mineral-based additives on composting and composting quality. Waste Manag 29:2265–2273. https://doi.org/10.1016/j.wasman.2009.03.016 CrossRefGoogle Scholar
- Iqbal MK, Shafiq T, Hussain A, Ahmad K (2010) Effect of enrichment on chemical properties of MSW compost. Biores Technol 101:5969–5977. https://doi.org/10.1016/j.biortech.2010.02.105 CrossRefGoogle Scholar
- Iqbal MK, Khan RA, Nadeem A, Hussnain A (2014) Conjunctive and mineralization impact of municipal solid waste compost and inorganic fertilizer on lysimeter and pot studies. Environ Technol 35(1–4):487–498. https://doi.org/10.1080/09593330.2013.833641 CrossRefGoogle Scholar
- Iqbal MK, Khan RA, Nadeem A (2015) Optimization of process parameters for kitchen waste composting by response surface methodology. Int J Environ Sci Technol 12:1759–1768. https://doi.org/10.1007/s13762-014-0543-x CrossRefGoogle Scholar
- Iqbal T, Jilani G, Siddique MT, Rasheed M (2016) Impact of rock phosphate enriched compost and phosphorus solubilizing bacteria on maize growth and nutrient uptake. J Agric Res 54(2):207–219Google Scholar
- Joardar JC, Rahman MM (2018) Poultry feather waste management and effects on plant growth. Int J Recycl Org Waste Agric. https://doi.org/10.1007/s40093-018-0204-z CrossRefGoogle Scholar
- Kalaivanan D, Hattab KO (2016) Recycling of sugarcane industries byproducts for preparation of enriched press mud compost and its influence on growth and yield of rice (Oryza sativa L.). Int J Recycl Org Waste Agric 5:263–272. https://doi.org/10.1007/s40093-016-0136-4 CrossRefGoogle Scholar
- Liang X, Jin Y, Hec M, Liud Y, Huaa G, Wange S, Tiana G (2017) Composition of phosphorus species and phosphatase activities in a paddy soil treated with manure at varying rates. Agric Eco Environ 237:173–180. https://doi.org/10.1016/j.agee.2016.12.033 CrossRefGoogle Scholar
- Lopez-Cano I, Roig Cayuela ML, Alburquerque JA, Sanchez-Monedero MA (2016) Biochar improves N cycling during composting of olive mill wastes and sheep manure. Waste Manag 49:553–559CrossRefGoogle Scholar
- Masungaa RH, Uzokwe VN, Mlay PD, Odeh I, Singh A, Buchan D, Neve SD (2016) Nitrogen mineralization dynamics of different valuable organic amendments commonly used in agriculture. Appl Soil Ecol 101:185–193. https://doi.org/10.1016/j.apsoil.2016.01.006 CrossRefGoogle Scholar
- Mohanty M, Reddy SK, Probert ME, Dalal RC, Rao SA, Menzies NW (2011) Modelling N mineralization from green manure and farmyard manure from a laboratory incubation study. Ecol Model 222:719–726CrossRefGoogle Scholar
- Nishanth D, Biswas DR (2008) Kinetics of phosphorus and potassium release from rock phosphate and waste mica enriched compost and their effect on yield and nutrient uptake by wheat (Triticum aestivum). Biores Technol 99:3342–3353. https://doi.org/10.1016/j.biortech.2007.08.025 CrossRefGoogle Scholar
- Olivaa SR, Mingoranceb MD, Peñab A (2017) Effect of two different composts on soil quality and on the growth of various plant species in a polymetallic acidic mine soil. Chemosphere 168:183–190. https://doi.org/10.1016/j.chemosphere.2016.10.040 CrossRefGoogle Scholar
- Saidi N, Cherif M, Jedidi N, Fumio M, Boudabous A, Hassen A (2008) Evolution of biochemical parameters during composting of various waste compost. Afr J Environ Sci 4:332–341. https://doi.org/10.3844/ajessp.2008.332.341 CrossRefGoogle Scholar
- Satisha GC, Devarajan L (2007) Effect of amendments on windrow composting of sugar industry pressmud. Waste Manag 27:1083–1091. https://doi.org/10.1016/j.wasman.2006.04.020 CrossRefGoogle Scholar
- Sun D, Lan Y, Xu EG, Meng J, Chen W (2016) Biochar as a novel niche for culturing microbial communities in composting. Waste Manag 54:93–100. https://doi.org/10.1016/j.wasman.2016.05.004 CrossRefGoogle Scholar
- Venglovsky J, Sasakova N, Vargova M, Pacajova Z, Placha I, Petrovsky M, Harichova D (2005) Evolution of temperature and chemical parameters during composting of the pig slurry solid fraction amended with natural zeolite. Biores Technol 96(2):181–189. https://doi.org/10.1016/j.biortech.2004.05.006 CrossRefGoogle Scholar
- Waqas M, Nizami AS, Aburiazaiza AS, Barakat MA, Ismail I, Rashid MI (2017) Optimization of food waste compost with the use of biochar. J Environ Manag 6:1–12. https://doi.org/10.1016/j.jenvman.2017.06.015 CrossRefGoogle Scholar
- Yadav H, Fatima R, Mathu Sharma A (2017) Enhancement of applicability of rock phosphate in alkaline soils by organic compost. Appl Soil Ecol 113:80–85. https://doi.org/10.1016/j.apsoil.2017.02.004 CrossRefGoogle Scholar
- Yee LL, Tin LC, Shiun LJ, Klemešd JJ, Siong HC, Mansorf NNA (2017) Feedstock amendment for the production of quality compost for soil amendment and heavy metal immobilization. Chem Eng Trans 56:409–504. https://doi.org/10.3303/CET1756084 CrossRefGoogle Scholar
- Zhang J, Chen G, Sun H, Zhou S, Zou G (2016) Straw biochar hastens organic matter degradation and produces nutrient-rich compost. Biores Technol 200:876–883. https://doi.org/10.1016/j.biortech.2015.11.016 CrossRefGoogle Scholar
- Zucconi F, Pera A, Forte M, Bertoldi MD (1981) Evaluating toxicity of immature compost. Biocycle. (22):44–46 http://aims.fao.org/serials/c_57e42005
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