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Biogas plant (BGP) with anaerobic digestion providing a facility to generate manure (Biogas spent slurry) and energy generation. The digested biogas slurry (DBGS) is rich in macro and micro nutrients that provide essential plant nutrients for longer period. Biogas slurry may be considered as a good quality organic fertilizer for sustainable agriculture. Biogas slurry provides huge nutrient potential for vegetative and reproductive growth of field crops with long term sustainability. By applying the digested biogas slurry (DBGS) in the field for long term basis help in reducing fertilizer demand and provide an eco-friendly way of maintaining productivity and soil health. In this study we are summarizing nutrient potential of digested biogas slurry (DBGS) and relation with synthetic fertilizers in India, as a potential source.
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REVIEW ARTICLE OpEn ACCEss
Biogas Slurry: Source of Nutrients for Eco-friendly Agriculture
Sandeep Kumar*, Lal Chand Malav, Mahesh Kumar Malav and Shakeel A Khan
Centre for Environment Science and Climate Resilient Agriculture
Indian Agricultural Research Institute, New Delhi 110012 India
Kumar et al. 2015. International J Ext Res. 2:42-46
http://www.journalijer.com
Abstract
Biogas plant (BGP) with anaerobic digestion providing a facility to generate manure (Biogas spent slurry) and energy genera-
tion. e digested biogas slurry (DBGS) is rich in macro and micro nutrients that provide essential plant nutrients for longer
period. Biogas slurry may be considered as a good quality organic fertilizer for sustainable agriculture. Biogas slurry provides
huge nutrient potential for vegetative and reproductive growth of eld crops with long term sustainability. By applying the
digested biogas slurry (DBGS) in the eld for long term basis help in reducing fertilizer demand and provide an eco-friendly
way of maintaining productivity and soil health. In this study we are summarizing nutrient potential of digested biogas slurry
(DBGS) and relation with synthetic fertilizers in India, as a potential source.
Keywords: Digested biogas slurry (DBGS), Nutrients, Sustainability, Fertilizers.
*Corresponding author e-mail: sandeep2011iari@gmail.com
International
JOuRnAL Of ExTEnsIVE REsEARCh
e-Print ISSN: 2394-0301
Introduction
Biogas slurry is a by-product of anaerobic digestion that pro-
duced from biogas plant and also produces biogas (combustible
methane gas) that is used for cooking, lighting and running en-
gines. Bioslurry can be used to fertilize crops directly or added
with other organic materials and synthetic fertilizers. Bioslurry is
a digested source of animal waste and if urine (animals) is added,
more nitrogen is added to the bioslurry which can speed up the
compost-making process in short period of time. This improves
the carbon/nitrogen (C/N) ratio in the slurry that provides easily
nutrient availability to plants and soil biota.
The biogas slurry has 93% water and 7% of dry matter, of
which 4.5% is organic matter and 2.5% inorganic matter. The di-
gested biogas slurry also contains phosphorus, potassium, zinc,
iron, manganese and copper, out of which many depleted from
soil due to intensive agricultural practices. Bioslurry can also be
used to build up health fertile soil for crop production. Bioslur-
ry contains easily-available plant nutrients and it contains higher
amounts of nutrients and micronutrients than composted manure
and FYM (Ishikawa et al. 2006). The effects of bioslurry applica-
tion are comparable to the effects of the application of synthetic
fertilizers. Hence, digested bioslurry can be a precious alternative
to synthetic fertilizers. Biogas slurry is considered a good source
of organic fertilizer as it contains considerable amounts of both
macro (N, P, K) and micronutrients (Zn, Mn, B) that are necessary
for plant growth (Alam, 2006). Use of biogas slurry is providing
a sustainable way for agriculture, environment and farming com-
munities.
Open
Journal
Page 1 of 5
Copyright © Kumar et al. 2015. Licensee IJER 2014. All rights reserved. is is an Open Access article distributed under the terms
of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, dis-
tribution, and reproduction in any medium, provided the original work is properly credited.
Survey
Potential of cattle dung in India
India has huge number of livestock population near about 512.05
million heads in 2012 (Dhikshit et al. 2010). In India, the total esti-
mated potential of biogas plant is 12 million but till now 4 million
plants are installed which can generate daily on an average basis
(Table 1) about 35 million cubic meter of biogas. So that, there is
only near about 33% of the potential over the period of almost 40
years has been achieved by this cumulative installation of biogas
plants (MNRE, 2004). The dung production capacity of animals
varies according to local conditions and feeding habit.
Page 2 of 5
Sl.
No. N (%) P (%) K (%) References
1 1-1.8 0.8-1.2 0.8-1 Gupta, 1991
2 1.4-1.8 01-Feb 0.8-1.2 DST, GOI (1981)
3 1.5-2 1 1 Tripathi, 1993
4 1.5 0.4 2.2 Board, 2007
5 1.3-2.5 0.9-1.9 1 Myles et al. 1993
6 0.5-1.0 0.5-0.8 0.6-1.5 Demont et al. 1990
7 1.5-2.0 1 1 Khandelwal et al . 1986
Table 2. Nutrient composition of biogas slurry
Head Dung (Kg/day) Biogas yield (m3/Kg)
Cattle 10 0.36
Bualo 15 0.54
Table 1. Per day dung production rate (Nagamani et al. 1999)
Total dung produced by animals in India is 730 MT per annum
(per day 2 MT dung), out of which only 60 % dung is recoverable
(collection rate varies from 58 % to 65 %). But we are basically
meeting our demand of dung through bovine dung (cattle+buf-
falo). They generate only 256.2 MT dung each year that also have
huge nutrient potential to full our fertilizer demand. On an aver-
age by 1 kg cattle dung only 0.3 kg slurry produced. So that total
slurry produced in India is 76.8 MT/year. On an average compo-
sition of biogas slurry is 1.5% N, 1.1% P and 1% K (Table 2).
Comparison of nutrition values
The slurry can with easily be brought to places that need organic
fertilizers. The most important benet is that the slurry is a very
effective fertilizer that can improve the growth of the crops (Ah-
mad et al. 2009). Nitrogen is one of the major nutrients required
for plant growth. Biogas slurry contains a considerable amount of
Organic material N (%) P (%) K (%)
FYM 0.5-1 0.5-0.8 0.5-0.8
Compost 0.5-1.5 0.4-0.8 0.5-1.9
Biogas slurry 1.4-1.8 1.1-2 0.89-1.2
Table 3. Comparison of nutrient content in FYM, compost and
biogas slurry (SNV, 2011)
both macro and micro nutrients besides appreciable quantities of
organic matter than other organic fertilizers like FYM and com-
post (Table 3). The concentration of toxic heavy metal is very low
compared to synthetic fertilizers. Biogas slurry (organic fertilizer)
is environmental friendly, has no toxic or harmful effects and can
easily reduce the use of synthetic fertilizers. The use of synthetic
fertilizers began in the country from 1960s with huge amount and
demand sharply increased with the introduction of high yielding
varieties of crops (MNRE, 2010).
Combined effect of biogas slurry (Dry-DBGS & Wet-DBGS)
and synthetic fertilizers
As we know, in traditional agricultural systems very less or no
synthetic fertilizers are applied, breakdown of organic materials
supplies the dominant portion of nitrogen, phosphorous and sul-
fur that play important role in plants metabolism. Organic matter
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Anuranjini and Alex, 2015. International J Ext Res. 2:42-46
greatly enhances the cation exchange capacity (CEC) of the soil
that has ability to capture positively charged ions such as Mg, Ca,
K and NH4
+. On other hand, when the CEC is low, these nutrients
would be rapidly leached away when it rained. Cation exchange
ability of the organic matter is particularly important in acid soils,
and those with low clay content since such soils have low binding
ability.
The combination of biogas slurry and synthetic fertilizers en-
hances the C:N transformation on the crop and increases the yield
by 6.5%, 8.9%, 15.2% and 15.9% of cotton, wheat, maize and
rice respectively (Table 4). The effect of biogas slurry depends on
the absorption rate of the crop at the time of application. Some
studies also showed that the yield of corn can increase by 7%
(Shahabz, 2011) and can be increase by 8.9% (SNV, 2011). Other
research shows that an application of 12 t/ha can increase the
yield and nutritional value of maize more than 10 t/ha or 14 t/
Crop Yield (kg/ha) % increment
DBGS FYM
Cotton 154.5 133.5 6.5
Wheat 450 390.5 8.9
Maize 555.9 510.4 15.2
Rice 634.4 597.5 15.7
Table 4. Comparison of the effects of DBGS and FYM on the yield of crops
Sl.
No. Treatments Yield (t/ha)
(3 years average)
Increment over con-
trol (t/ha)
1Control 1.28 -
2 Dry-DBGS 1.45 0.16
3 Wet-DBGS 1.84 0.55
4 50% Dry-DBGS+50% synthetic fertilizer 2.7 1.41
5 75% Dry-DBGS+25% synthetic fertilizer 1.74 0.45
6 Synthetic fertilizer 3.5 2.21
Table 5. Effect of wet and dry biogas slurry (DBGS) on wheat yield (Bhattarai et al. 1988)
ha of manure application (FYM). The highest biomass yield of
maize fodder can be observed with 54.12 t/ha of biogas slurry
application. There is no signicance increase in numbers of leaves
with combined effect of biogas slurry and synthetic fertilizer. The
following Table 5 shows that biogas slurry is not superior in terms
of its manurial properties as compared to both different combi-
nation of dry slurry (Dry-DBGS) and synthetic fertilizer or alone.
Dry slurry (Dry-DBGS) showed the lowest increment in wheat
yield, probably indicating the loss of nutrient during the drying
operation. Here, maximum increment was shown in application
of synthetic fertilizer alone. But it is not an appropriate way to
maintaining the sustainability of soil and produce for long period.
During digestion of biogas slurry, nutrients are transformed
from organic form to dissolved states (inorganic form), making
them more useful for plant uptake (Lansing et al. 2010). It is ob-
served that generally the rate of application of bioslurry is 10 to
20 t/ha in irrigated eld and 5 tons/ha in dry farming in order to
achieve a signicant increase in productivity (SNV, 2011). Gener-
ally the additional increase in yield is not more than 25 t/ha. This
yield also depends on soil parameters, crop varieties and availabil-
ity of irrigation.
Fertilizer replacement
Synthetic fertilizers can increase the soil’s nutrients more than or-
ganic fertilizers. But synthetic fertilizers are able to provide only
particular nutrients to the crops. Farmers use synthetic fertiliz-
ers to increase crop production immediately that on other hand
intense and continuous use of such synthetic fertilizers creates
crops that are susceptible to insect attacks, microbial pathogens
and intrusive weeds. If only synthetic fertilizers are added to the
soil, without organic manure (slurry, FYM and compost) decreases
soil productivity and if only organic manure is added, decrease
the desired crop yields (Liu et al. 2009). Most of time, optimum
crop yield and soil fertility levels can be achieved through the com-
bination of synthetic and organic fertilizers. Synthetic fertilizers
are expensive and most small-scale farmers cannot afford them
for a long duration. The high costs involved make it essential for
most of developing and African countries to nd an alternative to
synthetic fertilizers (Dahiya et al. 1985). Furthermore, often the
bioslurry combined with synthetic fertilizers shows better yields
than bioslurry utilization on its own (Groot et al. 2013).
The use of biogas slurry reduces costs, as synthetic fertilizers
are no longer necessary and crop production increases. Due to the
results of the different studies and taking into account environ-
mental effects and costs of synthetic fertilizers, using around 10
to 15 t/ha of biogas slurry is suggested, starting fertilizing after
ploughing and 21 to 28 days before planting. Once the sprouts are
above ground biogas slurry application should be done solely by
spreading it onto the roots of the plant at noon while mixing it
with the soil (Karki, 2001).
However, the economic value of organic fertilizer to a farmer
is the value of increase in crop yields and/or crop quality that is
derived from its use. The cost benet ratio will determine the eco-
nomic aspects of its use (Alam, 2006).
One cubic meter slurry contains 0.16 – 1.05 Kg N which is
equivalent to 0.35-2.5 Kg urea (Vinh, 2010).
The nitrogen content of slurry is 1.5% (1.5% N, 1.1% P and
1% K).
From 730 MT dung, 76.8 MT slurry produced per year (only
for bovine dung).
In 76.8 MT slurry, nitrogen content is 1.15 MT nitrogen.
1 kg Nitrogen is equivalent to 2.2 kg Urea fertilizer (Urea con-
tains 46 % N).
Cost of urea is Rs. 276/50 kg bag
So cost of 1.15 × 109 kg N will be 13.74×109 INR.
As per above estimation, we can say that 76.8 MT slurry ef-
fectively reduce import bill by 13.74 billion INR. Mineral fertiliz-
ers alone cannot correct all the nutrients deciency in agricultural
soils. The prices of the imported fertilizers will continue to in-
crease in from last few decades. Therefore, transformation of all
native organic resources and recycling them into soil fertilization
program should be undertaken early as much possible. The use
of biogas slurry can reduce the application of synthetic fertilizers
to a great extent. It is possible to reduce the use of the synthetic
fertilizers up to 15-20%.
Conclusions
Biogas slurry may be considered as a good quality organic fertilizer
in sustainable agriculture for maintaining the quality of produce.
Biogas slurry has potential to provide a considerable amount of
both macro and micro nutrients besides appreciable quantities of
organic matter. Along the richness in nutrients it also has very low
amount of heavy metals as compared to synthetic fertilizers. Bio-
gas slurry (Dry-DBGS & Wet-DBGS) is environmental friendly,
has no toxic or harmful effects and can easily reduce the use of
chemical fertilizers up to 15-25%.
Biogas slurry has signicant potential to improve the physical
and biological quality of soil (improvement in soil structure, im-
provement in water holding capacity, cation exchange capacity,
lesser soil erosion and provision of nutrients to soil micro-ora
including nitrogen xing and phosphorous solubilizing organ-
isms) besides providing both macro and micro-nutrients to crops.
Yield increases due to biogas slurry application, have also report-
ed for many crops including eld crops, tobacco, castor, peas,
mustard, onion, cabbage, banana, chillies, pearl millet and sugar-
cane. A combination of biogas slurry (Dry-DBGS & Wet-DBGS)
and synthetic fertilizer enhanced carbon nitrogen transformation
with substantive effect on crop yield. Finally, we come out with
conclusion that biogas slurry provide a benecial way for farmer’s
community, reduce fertilizer burden on economy of country and
improve sustainability of eld.
Conict of interests
The author(s) declare(s) that they have no conict of interests.
Acknowledgment
The authors are thankful to the Post Graduate School and Di-
rector, Indian Agricultural Research Institute, New Delhi, India
for providing for fellowship towards M.Sc. programme of the
rst author. We are also grateful to the Centre for Environment
Science and climate Resilient Agriculture, Indian Agricultural Re-
search Institute, New Delhi for providing necessary facilities for
undertaking this study.
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Article Information:
Received: 15 January 2015
Accepted: 20 February 2015
Online published: 23 February 2015
Cite this article as:
Kumar et al. 2015. Biogas slurry: source of nutrients for eco-friendly
agriculture. International Journal of Extensive Research. Vol. 2: 42-46.
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... However, long-term excessive use of CF decreases organic soil carbon (C), microflora and fauna and overall soil quality, increase greenhouse gas emissions (FAO, (Food and Agriculture Organization) 2017;MacCarthy et al. 2018) and could contaminate water bodies (Rahman et al. 2008;Shahbaz et al. 2014). In addition, each CF provides only particular essential nutrients to the crop (Kumar et al. 2015). Smallscale farmers, including those in South Africa use CF for crop production, however they do not apply sufficient quantities due to high cost of CF (Kumar et al. 2015), and that could reduce potential yields targets. ...
... In addition, each CF provides only particular essential nutrients to the crop (Kumar et al. 2015). Smallscale farmers, including those in South Africa use CF for crop production, however they do not apply sufficient quantities due to high cost of CF (Kumar et al. 2015), and that could reduce potential yields targets. However, co-application of CF with organic fertilizers could add extra nutrients especially from the organic sources which would otherwise have to be disposed of, presenting risks on the environment (e. g eutrophication of waters). ...
... The biogas technology produces energy (methane) through anaerobic digestion of organic wastes, like animal manures, thereby reducing environmental pollution (Islam, Rahman, and Rahman 2010). Biogas slurry, a by-product after anaerobic digestion of organic waste, contains large amounts of micro and macronutrients, necessary for plant growth (Abubaker, Risberg, and Pell 2012;Kumar et al. 2015;Muhmood et al. 2014). The slurry can act as a soil conditioner, while its decomposition mineralizes essential nutrients, increasing their availability in soil and crop biomass accumulation and yield (Cameron et al. 2004). ...
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Soil is a living and dynamic body, which is prone to degradation under conventional agricultural practices. Healthy soil is one of the most important pillars of sustainability as it delivers several ecosystem services along with its control on microbial activity, nutrient recycling, and decomposition. Nature-based solutions can play an important role in restoring soil quality for enhanced agricultural productivity and sustainability.
... Biogas slurry may be considered as a good quality organic fertilizer for sustainable agriculture. A combination of biogas slurry (Dry-DBGS & Wet-DBGS) and synthetic fertilizer enhanced carbon nitrogen transformation with substantive effect on crop yield [11]. After generation of biogas we applied this slurry around the base of a "money plant" (Epipremnumaureum) and kept it for 12-14 days under sunlight. ...
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Nowadays Industrial waste management is the key concern over the world. Biogas generation and bio-compost from knitting, cutting, spinning waste is one of the right and sustainable way of waste management. Wastage is generated almost all process in spinning, knitting and cutting in the industry. Cotton contains huge amount of dust, foreign-matters, seed and other particles. Micro dust of cotton waste has no salability and pollutes the atmosphere. Mostly, it is disposed of by burning as a result increase the CO2 level in the atmosphere which is the threat for environment as pollutes the surrounding areas. The main objective of this project is sustainable use of cotton waste by producing biogas and utilization of Slurry after Biogas Generation. Biogas generation by anaerobic digestion is sustainable, cost effective and eco-friendly method in Bangladesh. Finally, our concern is to maximum utilization all collected cotton wastes in a sustainable way i.e. anaerobic digestion way. Our experiments on wastes where those wastes produced bio-gas such as spinning cotton micro dust: 1st of all for production of gas to observe; after 30-40 days of feeding 180cc biogas was generated from 100g cotton spinning dust via lab scale biogas plant & gas also confirmed via flammability test. On the other hand smaller size of cotton cutting jhut fabric show comparatively low gas production and found that gas production depend on decomposition rate of cotton waste. Slurry treatment applied in a plant after generation of biogas and output of this application showing that many new leafs were grown and looking more refresh within 12-14 days. So, unusable spinning cotton waste can be resources for our economy and environment instead of hazards or waste. We have recommended that yarn singeing machine can be run by produced biogas.
... Kumar et al. confirmed in 2015 that the concentration of toxic heavy metals in digestate is very low compared to synthetic fertilizers. The use of digestate as a fertilizer reduces the use of synthetic fertilizers, thereby reducing costs, and digestate is also environmentally friendly [76]. ...
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The effectiveness of biogas plant slurry in combination with chemical fertilizers was studied for the production of various crops. Replacement of nitrogenous fertilizer with slurry decreased the yields of major crops, i.e. wheat, bajra, jawar and mustard. Application of slurry to replace half the nitrogenous fertilizer gave better yields in vegetable crops while replacement of the total nitrogenous fertilizer gave better yields in fodder crops.
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Vegetables, the indispensable staple produce providing humans with many beneficial substances, are readily contaminated by nitrate, heavy metals and pesticides during conventional cultivation. In particular, off-season vegetables grown in protected systems with low light intensity do tend to accumulate more nitrate in tissues due to excess N fertilization driven by farmers' desire for high yields. Over-the-limit accumulation of the harmful substances in vegetables constitutes a serious hazard to human health globally. Soilless cultivation, currently a fraction of vegetable cultivation in China, is a promising cultivation method to decrease the accumulation of harmful substances through nutrient solution regulation and environmental factor control. However, conventional inorganic nutrient solutions present few quality benefits besides plant nutrition for the widely acknowledged formulations. Currently, high-quality vegetables are urgently desired by humans globally, but they are difficult to grow for lack of an effective and practical cultivation method to lower the accumulation of harmful substances and to improve nutritional quality simultaneously. Although some attempts have been made, few commercial formulations have been applied in practice. Biogas manure (biogas slurry and biogas dregs) is a by-product of biogas production. It has been shown to be a good fertilizer with abundant nutrients, amino acids and bioactive substances. In China, as a product of the recycling process of agricultural wastes, biogas manure is an ever-growing resource due to the rapid development of biogas projects. Therefore, the need to utilize biogas manure is an urgent issue that relates both to environment protection and nutrient resources utilization. In this paper, the updated research results on yield and the quality effects of vegetables cultivated with biogas dregs and the solutions modified from biogas slurry in China are summarized, highlighting the feasibility and benefits of biogas manure in high-quality vegetable production. It is concluded that biogas manure is an effective nutrient source for high-quality vegetable production based on its synergistic effects and effectiveness in yield and quality improvement (particularly depression effects on nitrate accumulation), and stress resistance. However, deliberate component regulations need to be developed for better yield and quality of vegetables under soilless cultivation due to the large variability of components of biogas manure caused by various combinations of fermentative materials.
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Biogas plant (BGP) with anaerobic digestion is receiving high attention as a facility for both livestock manure treatment and electric power generation. The objective of the study was to compare an on-farm BGP with a centralized BGP system totally from the energetic point of view. The basic data for this evaluation were obtained from the centralized BGP in Betsukai, Hokkaido, which was built on May 2001 for the experimental purpose by the Civil Engineering Research Institute of Hokkaido. We used two evaluation methods. First, to estimate how global warming gas is influenced by BGP systems, we used life cycle assessment (LCA). Estimated emission of CO2 was about 2700 t from the introduction of BGP. The production of CO2 at the time of biogas combustion (1080 t) was not included in emission because of the concept of carbon neutral.
Production of organic manure in Bangladesh
  • S Alam
Alam, S., 2006. Production of organic manure in Bangladesh, Bangladesh Livestock Research Institute's Report, Savar, Dhaka, Bangladesh.
Effect of Azotobactor Inoculation in Combination with Different Sources of Organic Manures
  • S Bhattarai
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Bhattarai, S., Maskey, S.L, 1988. 'Effect of Azotobactor Inoculation in Combination with Different Sources of Organic Manures.' Proceedings of National Conference on Science and Technology, April 24-29, 1988, pp 81-85. Khumaltar, Kathmandu: Division of Soil Science and Agricultural Chemistry.