Enhanced bio-composting of rice straw using agricultural residues: an alternate to burning
- 736 Downloads
Rice straw which predominantly contains cellulose, hemicellulose and lignin, can be converted into value-added product such as bio-compost. The present study was planned to carry out rice straw degradation, added with agricultural residues like rice bran and fruit waste in different combinations, with standard fungal culture of Trichodermaharzianum MTCC 8230.
Rice straw added with fruit waste and rice bran was moistened with sterilized water in five different proportions. The experimental trays were inoculated with spore suspension (1 × 108 spores/ml) of T. harzanium. The trays were observed for change in pH, appearance and chemical fibres (acid detergent fibre, neutral detergent fibre, and acid detergent lignin).
A continuous increase in bulk density accompanied with a decrease in volume was observed in all the experimental trays including the control. There was an initial increase in pH from 7 to 9 which stabilized to 8 after 12 days of incubation. The crystalline structure of rice straw was transformed into amorphous one in a time frame of 28 days, with a significant decrease in lignin from 20–25% to 13–15% and an increase in crude protein from 5–17%.
The crystalline rice straw was reduced to a brown crumpled and compact value-added composted biofertlizer with a high carbon and crude protein content.
KeywordsRice straw Rice bran Fruit waste Bio-compost Trichoderma harzianum
Amongst the different lignocellulosic crop residues in India, rice straw constitutes the largest proportion, with a production of 112 million metric tons per annum (Sukumaran et al. 2010). However, a vast proportion of this rice straw is subjected to open-field burning which is hazardous for the environment. Rice straw possess various several characteristics that make it an ideal feedstock for value-added products such as animal feed, bioethanol, lignocellulose enzyme, and bio-compost. The rice straw is chiefly composed of cellulose (32–47%), hemicellulose (19–27%) and lignin (5–24%) (Garrote et al. 2002). Therefore, the hidden value of rice straw can be explored by biological conversion of polysaccharides into aforementioned value-added products.
Composting is a bio-oxidative process which involves the conversion of organic waste to a stabilized final product free of phytotoxicity and pathogens, by the process of mineralization and partial humification (Inckel et al. 1996). It can be made on the farm at very low cost and can be used as organic fertilizer (Zucconi et al. 1981). Therefore, the rationale of the present study was to convert rice straw into organic fertilizer to mitigate its open-field burning.
Collection of rice straw and fungal culture
Rice straw was collected from School of Renewable Energy Engineering, Punjab Agricultural University (PAU), Ludhiana. The rice straw was washed thoroughly with tap water, chopped and sieved to 30 mesh size. Rice bran and fruit waste were collected from the local market. The materials were stored in clean plastic bags at room temperature for further analysis and treatment. The fungal culture Trichodermaharzianum MTCC 8230 was procured from department of Microbiology, PAU, Ludhiana.
Experimental plan of rice straw bio-composting
Rice straw (g)
Fruit waste (g)
Rice bran (g)
The pHs of the contents were also recorded by using a pH paper strip of range 3–10. The contents were replenished in trays that were placed in BOD incubator maintained at 30 °C.
Chemical fibre analysis
To evaluate the biodegradation rate, the samples were analyzed for acid detergent fibre (ADF), neutral detergent fibre (NDF) and acid detergent lignin (ADL) by the method of Goering and Van Soest (1970). The crude fibre protein determination was carried out with the help of department of Animal nutrition, Guru Angad Dev Veterinary and Animal Sciences University (GADVASU), Ludhiana.
All experiments were carried out in triplicates and all the values are mean ± standard error (SE), calculated using the MS excel program.
Results and discussion
Changes in bulk density, pH, and physical parameters
Physical appearance of rice straw during and after bio-composting
Fragile, smooth textured
Non fragile, rough textured
Non fragile, crumpled, crust textured
White fungal mycelium visible
No visible growth
Changes in chemical characteristics of compost.
Chemical composition of rice straw during and after bio-composting
Treated rice strawa
40 ± 1.2
43 ± 1.4
43 ± 1.4
22 ± 0.7
18 ± 0.6
16 ± 0.5
24 ± 0.8
18 ± 0.6
15 ± 0.5
Crude protein (%)
5 ± 0.2
10 ± 0.3
17 ± 0.5
The crystalline rice straw with a low bulk density, which occupied a large volume was reduced to a brown, crumpled and compact value-added composted biofertilizer. The said biofertilizer possessed a high carbon and crude protein content that can help provide a green technique for the improvement of soil health by supplementing the C and N pool of the soil and thus alleviate the farming cost.
- Goering H K, Van Soest P J (1970) Forage fiber analyses (apparatus, reagents, procedures, and some applications), Agriculture handbook no. 379, Agriculture Research Service USDA, Washington (DC), USA, pp 20Google Scholar
- Inckel MP, Smet D, Tersmette T, Veldkamp T (1996) The preparation and use of compost, 4th edn. E.W.M. Verheij, Wagenningen, The Netherlands, Trans, p 28Google Scholar
- NRAES (2001) Proceedings from, dairy manure systems—equipment and technology, Rochester, New York, March 20–22. Agriculture, and Engineering Service, Cooperative Extension, Ithaca, New York, Natural Resource, p 424Google Scholar
- Smars S (2002) Influence of different temperature and aeration regulation strategies on respiration in composting of organic household waste, Department of Agricultural Engineering, Swedish University of Agricultural Sciences: Doctoral thesis, Agraria 324. Uppsala, SwedenGoogle Scholar
- Zucconi F, Pera A, Forte M, De Bertoldi M (1981) Evaluating toxicity of immature compost. Biocycle 22:54–57Google Scholar
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.