Influence of Flyash and Sewage Sludge Application on Growth and Yield
of Annual Crops
V. K. Kauthale, P. S. Takawale, P. K. Kulkarni and J. N. Daniel
International Journal of Tropical Agriculture. Vol. 23 (1-4): Jan-Dec. 2005:
49-54.
Abstract
Experiments were conducted in sequence for four seasons from the rainy
season of 1998 to the post-rainy season of 1999 at the Central Research
Station of BAIF Development Research Foundation, Pune, Maharashtra to
study the effect of recurring applications of flyash and sewage sludge on the
growth and yield of French bean, soybean and radish. A mixture of flyash and
sludge, each at 26 t ha-1, increased the yield of French bean and soybean by
53% and 30%, respectively, over the control treatment that received NPK
fertilizers at recommended rates. Radish grown with the application of only
sludge at 52 t ha-1 yielded 24% and 80% more than the control during the two
seasons of its cultivation. Unlike sewage sludge or the flyash-sludge mixture,
the application of only flyash at 52 t ha-1 did not sustain crop yields.
Keywords: Fly ash, sewage sludge, organic matter, minerals, nutrients, yield
Introduction
A major determinant of the productivity of a soil is its nutritional status.
Besides the major constraint of availability of water, low soil fertility and the
inability to afford chemical fertilizers limit crop production in dry tropical
regions. Many waste materials containing essential plant nutrients are
available in huge quantities in these areas. These materials when applied at
appropriate rates can enhance the nutrient status as well as other soil
properties.
Flyash is the major solid waste produced in thermal power stations.
The quantity of flyash produced annually by the 70 thermal power plants in
the country is estimated to be 50-60 million tons. In the absence of a wellplanned strategy in India for the disposal of this flyash, it is posing serious
health and ecological hazards (Kanojia et al. 2001). Flyash contains plant
nutrients and can be used for crop production (Arvind Kumar et al. 1999).
Another waste suitable for crop production is the sludge produced by sewage
treatment plants as it is rich in crop nutrients (Dowdey et al. 1976). Therefore,
the value of flyash and sewage sludge as sources of crop nutrients and soil
ameliorants were examined during four cropping seasons. The results of these
experiments that examined the influence of flyash and sewage sludge, alone or
in combination, on the growth and yield of three annual crop species are
presented in the current paper.
Materials and Methods
Field experimentation was initiated during the rainy (kharif) season of 1998 at
the Central Research Station of BAIF Development Research Foundation at
Urulikanchan in Pune District of Maharashtra. The experiments were
conducted on a field having sandy clay soil with a pH value of 7.8. The
treatments of the study are described in Table 1.
The quantity of flyash, sewage sludge and fertilizers for each plot were
manually incorporated into the soil. There were six treatment combinations,
each replicated four times and arranged in a randomised block design. The
flyash for the experiment was obtained from the National Thermal Power
Corporations’s plant at Eklahare, Nashik and Sinarmas Pulp and Paper (India)
Limited, Bhigwan, Pune. Sewage sludge was collected from the sewage
treatment plant of Pimpri-Chinchwad Municipal Corporation at Chikhali. The
pH of the flyash was 7.15 and that of the sludge was 5.78.
The kharif crops for the 1998 and 1999 seasons, respectively, were
local selection of French bean (Phaseolus vulgaris) and MACS-58 is variety
of soybean (Glycine max) while Japanese white variety of radish (Raphanus
sativus L.) was the post-rainy season (rabi) crop for both years. The land was
prepared adopting the standard method for each crop. In the plots receiving
flyash and sewage sludge, the bulky material was incorporated and mixed
thoroughly with the soil before the establishment of the kharif crop.
Recommended spacing and agronomic practices were followed for all crops.
Observations on growth and yield parameters were recorded periodically and
the data subjected to Analysis of Variance.
Results and Discussion
Results of kharif crops of 1998 (French bean) and 1999 (Soybean) post-rainy
season are presented in Table 2. In both crops, the influence of the treatments
on the parameters measured was significant. In general, the treatments that
had sewage sludge resulted in taller plants, greater dry matter accumulation
and higher grain yield. The treatment receiving the flyash-sludge mixture (26
t ha-1 each) recorded the highest grain yield, which was 53% more than the
yield with the recommended rate of fertilizer application. The response of
soybean during the following kharif season in 1999 also followed a similar
trend. The plant height and grain size of soybean was influenced positively by
the application of 52 t ha-1 of sewage sludge. But the highest yields of
soybean were obtained in the treatment having a combination of flyash and
sludge at 26 t ha-1. Thus it is evident that the benefits are related to crop
nutrients as well as other soil properties associated with organic matter.
The experimental site had very low organic matter and this was
probably the reason for the greater response of the treatments receiving sludge.
The minerals in the flyash and the organic matter in the sludge seem to have
benefited the growth and yield of both French bean and soybean. Selvakumari
et al. (2000) reported highest yield in rice when flyash was applied in
combination with compost, fertilizer and Azospirillum.
Growth and yield parameters of radish crops grown during the rabi
seasons of 1998 and 1999 are presented in Table 3. The yield components of
radish were significantly influenced by the treatments. The root length of the
treatment receiving flyash, sludge and chemical fertilizer was the highest
while the treatments receiving only flyash had the shortest roots. The addition
of large quantities of flyash, an amorphous material, appeared to make the soil
heavy and compact, which probably resulted in the reduced length of flyash
roots. Thus, the root length of radish in the treatment receiving 52 t ha -1 of
flyash was 17.6% and 24.5% lower than those receiving the recommended rate
of chemical fertilizer and the combination of all three inputs, respectively.
The treatment effects on root diameter were generally similar to that on root
length.
Significant treatment differences were observed in the yields of radish
(Table 3). In the first year of the study, the highest yield was in the treatment
that received 52 t ha-1 of sewage sludge. It produced 24.2% more yield than
that treated with the recommended rate of fertilizer. Because the soil in which
this experiment was conducted is low in organic matter and fertility, it seems
to have benefited from the constituents of the sludge. Gupta et al. (1989)
reported a similar increase in wheat yield by the application of sludge. The
combination of flyash (26 t ha-1), sludge and fertilizer produced about 19%
more yield than the treatment applied with the recommended rate of fertilizer.
This is beneficial as it not only cuts down on the recommended fertilizer
dosage by half, but also results in higher yield. Maynard (1993) reported
similar results in tomato by using source-separated municipal solid waste
compost at 50 t ha-1.
The treatment responses exhibited by radish in the first rabi season
were again observed in the cycle again a year later (Table 3). In particular, the
cumulative effect of receiving 52 t ha-1 year-1 of sludge for two consecutive
years resulted in a radish yield of 45 t ha-1. This was 36% more than the next
best treatment. Besides yield, the other parameters also showed significant
treatment differences.
The cumulative effect of the treatments on crop yield is presented in
Figure 1 by expressing the treatment yields as a percentage of the yield of the
control. The control for this purpose was the treatment that received the NPK
fertilizer at the recommended rate. Application of fertilizers at 50% of the
control resulted in marked reduction in the yield of all crops. This indicates
that the native fertility of the soil at the experimental site is inadequate to
realise the crop potential. Among the treatments investigated, the application
of sludge alone, a flyash-sludge mixture or a flyash-sludge-fertilizer mixture
overcame this soil deficiency. Moreover, it was seen that the benefit from the
application of only sewage sludge was greater than the application of only
flyash.
The year-to-year production performance is a key consideration from a
long-term flyash and sludge usage standpoint. In this regard, the treatments
that received both flyash and sludge showed greater stability and produced
greater yield than the control treatment. The application of only sludge to the
soil resulted in an increasing trend whereas the reverse was true for flyash.
Continuous incorporation of huge quantities of flyash alone, as was the case in
this study, may affect crop production. On the contrary, comparable quantities
of sewage sludge appear to be beneficial for repeated use as they can increase
soil organic matter besides supplying crop nutrients.
Conclusion
The experimentation on the potential of flyash and sewage sludge revealed
that the application of flyash alone at doses as high as 52 t ha-1 cannot sustain
crop yields at high levels. It was also evident that sewage sludge, either alone
or in combination with flyash, has the potential to increase the yields of all
crops. Moreover, the results showed that the application of flyash and sludge,
with or without NPK fertilizers, results in higher yields than fertilization at
recommended rates.
Acknowledgements
The authors gratefully acknowledge the sponsorship received from the IndiaCanada Environment Facility and the Canadian International Development
Agency through the Indian Institute of Technology, Kharagpur and the
University of Western Ontario, Canada. They are also thankful to the Thermal
Power Plant, Eklahare and Sinarmass Pulp and Paper (India) Limited,
Bhigwan for providing flyash and Pimpri-Chinchawad Municipal
Corporation’s sewage treatment plant, Chikhali for providing sludge for the
experiments.
References
Arvind Kumar, Sarkar, A. K., Singh, R. P. and Sharma, V. N. (1999). Effect
of flyash and fertiliser levels on yield and trace metal uptake by soybean and
wheat crop. Journal of the Indian Society of Soil Science, 47(4): 744-748.
Dowdy, R. H., Larson, R. E. and Epstein, E. (1976). Sewage sludge and
effluent use in agriculture. In Land Application of Waste Materials. Ankeny,
Iowa: Soil Conservation Society of America. 138-153
Gupta, A. P., Narwal, R. P. and Antil, R. S. (1989). Effect of different levels
of nitrogen and sewage sludge on wheat. Journal of the Indian Society of Soil
Science 37: 576-578.
Kanojia, R. K., Kanawjia, S. K. and Srivastava, P. C. (2001). Utilisation of
flyash in agriculture: a potential soil amendment for increasing crop yields,
Indian Farming, June 2001, 29-32.
Maynard, A. A. (1993). Nitrate leaching from compost-amended soils.
Compost Science and Utilisation, 1(2): 65-72.
Selvakumari, G., Bhaskar, M., Jayanthi, D. and Mathan K. K., (2000). Effect
of integration of flyash and fertilisers and organic manure on nutrient
availability, yield and nutrient uptake of rice on Alfisols. Journal of the
Indian Society of Soil Science. 48: 268-278.
Table 1. Treatment descriptions of the experiment
Treatment
Number
Flyash
(t ha-1 year--1)
1
2
3
4
5
6
52 t ha-1
26 t ha-1
26 t ha-1
Quantity Applied
Sewage sludge
NPK fertilizer (kg/ha)
-1
-1
(t ha year )
French bean Soybean Radish
50:110:110 20:80:40 20:20:80
25:55:55
10:40:20 10:10:40
52 t ha-1
-1
26 t ha
-1
26 t ha
25:55:55
10:40:20 10:10:40
Table 2. Growth and yield parameters of kharif crops: French bean (1998) and
Soybean (1999).
Treatment
Fertiliser (#100%)
Fertiliser (##50%)
Flyash (52 t / ha)
Sludge (52 t / ha)
Flyash-Sludge
Ash-Sludge-Fert
SE +
French bean
Height at Dry weight
maturity at 50 DAS*
(cm)
(g/plant)
32.20
7.80
26.65
6.60
28.15
7.60
30.70
9.20
30.85
8.80
31.75
7.20
2.17
0.74
Grain
yield
(t/ha)
0.17
0.11
0.14
0.21
0.26
0.19
0.03
*Days after sowing; #Recommended fertiliser rate:
fertiliser
##
Soybean
Height at Grain 100 seed
maturity yield
weight
(cm)
(t/ha)
(g)
32.10
0.53
10.81
25.85
0.42
10.80
27.25
0.37
10.62
34.85
0.60
12.38
31.35
0.69
12.03
29.85
0.66
11.90
3.21
0.14
0.22
50% of recommended
Table 3. Growth and yield parameters of radish in the rabi seasons of 1998
and 1999.
Treatment
Fertiliser (#100%)
Fertiliser (##50%)
Flyash (52 t / ha)
Sludge (52 t / ha)
Flyash-Sludge
Ash-Sludge-Fert
SE +
Root
length
(cm)
18.65
16.35
15.37
17.72
17.32
20.37
0.85
1998
Root
diameter
(cm)
3.42
2.53
2.35
2.60
2.61
2.95
0.30
Yield
(t ha-1)
21.02
12.36
22.68
26.11
23.84
25.00
2.09
Root
length
(cm)
17.45
17.25
17.52
18.25
17.57
18.15
0.59
1999
Root
diameter
(cm)
2.47
2.36
2.32
2.58
2.47
2.58
0.07
Yield
(t ha-1)
25.04
20.78
18.01
45.09
31.25
33.10
4.03
*Days after sowing; #Recommended fertiliser rate:
fertiliser
##
50% of recommended
Figure 1. Cumulative effect of fly ash and sludge application on crop yield
Yield as a % of control
200
150
100% NPK
50% NPK
100% Ash
100
100% Sludge
50%A 50%S
50
50-50-50
0
Frenchbean(R 98)
Radish (PR 98)
Soybean (R 99)
Crops
Radish (PR 99)