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 well-planned 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 India-Canada 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 / Quantity Applied
Flyash
(t ha-1 year--1) / Sewage sludge
(t ha-1 year-1) / NPK fertilizer (kg/ha)
French bean / Soybean / Radish
1 / - / - / 50:110:110 / 20:80:40 / 20:20:80
2 / - / - / 25:55:55 / 10:40:20 / 10:10:40
3 / 52 t ha-1 / - / - / - / -
4 / - / 52 t ha-1 / - / - / -
5 / 26 t ha-1 / 26 t ha-1 / - / - / -
6 / 26 t ha-1 / 26 t ha-1 / 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

/ French bean / Soybean
Height at maturity (cm) / Dry weight at 50 DAS* (g/plant) / Grain yield
(t/ha) / Height at maturity (cm) / Grain yield
(t/ha) / 100 seed weight
(g)
Fertiliser (#100%) / 32.20 / 7.80 / 0.17 / 32.10 / 0.53 / 10.81
Fertiliser (##50%) / 26.65 / 6.60 / 0.11 / 25.85 / 0.42 / 10.80
Flyash (52 t / ha) / 28.15 / 7.60 / 0.14 / 27.25 / 0.37 / 10.62
Sludge (52 t / ha) / 30.70 / 9.20 / 0.21 / 34.85 / 0.60 / 12.38
Flyash-Sludge / 30.85 / 8.80 / 0.26 / 31.35 / 0.69 / 12.03
Ash-Sludge-Fert / 31.75 / 7.20 / 0.19 / 29.85 / 0.66 / 11.90
SE + / 2.17 / 0.74 / 0.03 / 3.21 / 0.14 / 0.22

*Days after sowing; #Recommended fertiliser rate: ##50% of recommended fertiliser

Table 3. Growth and yield parameters of radish in the rabi seasons of 1998 and 1999.

Treatment

/ 1998 / 1999
Root length (cm) / Root diameter (cm) / Yield
(t ha-1) / Root length (cm) / Root diameter (cm) / Yield
(t ha-1)
Fertiliser (#100%) / 18.65 / 3.42 / 21.02 / 17.45 / 2.47 / 25.04
Fertiliser (##50%) / 16.35 / 2.53 / 12.36 / 17.25 / 2.36 / 20.78
Flyash (52 t / ha) / 15.37 / 2.35 / 22.68 / 17.52 / 2.32 / 18.01
Sludge (52 t / ha) / 17.72 / 2.60 / 26.11 / 18.25 / 2.58 / 45.09
Flyash-Sludge / 17.32 / 2.61 / 23.84 / 17.57 / 2.47 / 31.25
Ash-Sludge-Fert / 20.37 / 2.95 / 25.00 / 18.15 / 2.58 / 33.10
SE + / 0.85 / 0.30 / 2.09 / 0.59 / 0.07 / 4.03

*Days after sowing; #Recommended fertiliser rate: ##50% of recommended fertiliser


Figure 1. Cumulative effect of fly ash and sludge application on crop yield