Effect of liquid bioinoculants, organic and chemical additives on rate of decomposition and quality of sugarcane trash compost

Introduction

In India, approximately 6.5 million tons of sugarcane trash are produced annually, with most residues typically burned in the field due to a lack of proper composting techniques (Mohan and Ponnusamy 2011) [23] . Hence, there is substantial economic interest in advancing technologies and processes for the efficient utilization of these wastes (Zhang et al., 2000) [31] . The focus has shifted towards aerobic composting, which transforms wastes into organic manure enriched with plant nutrients and humus (Singh and Sharma, 2002), as well as the biodegradation of lignocellulosic wastes through integrated composting systems with bioinoculants. To rejuvenate soil productivity, adopting practices such as recycling crop biomass such as sugarcane residues and left over crop material, presents a promising alternative (Gaind and Nain 2007) [11] . Utilizing these plant residues, whether composted or otherwise, can serve as a cost-effective alternative to inorganic fertilizers, able it they may yield early compost with limited nutrient content. Enriching compost with mineral additives can effectively boost the growth and efficacy of indigenous fungi, accelerating the decomposition process of sugarcane trash. For decomposition of 1 ton sugarcane crop residues added 8 kg Urea + 10 kg SSP + 1 kg decomposing culture (Ghodke et al., 2020) [13] . The cellulose-decomposing microbes play a vital role in preserving the carbon equilibrium in nature, particularly evident in the decomposition of sugarcane trash, which ultimately fosters humus formation and enhances soil fertility. Composting is a thermophilic process that can be aerobic or anaerobic, requiring aeration to stabilize organic wastes and maintaining optimal moisture levels for microbial activity. Compost is the result of composting, characterized as a stabilized and sanitized product that undergoes an initial rapid decomposition stage. It is advantageous for plant growth, making the quality of compost crucial in waste composting for sustainable agriculture and resource management (Gajalakshmi and Abbasi, 2008) [12] . The composting process progresses through four distinct phases: 1. In the initial mesophilic phase (10-42 °C), temperatures rise swiftly, triggering decomposition of organic matter. During the thermophilic phase (45-70 °C), 3 sustained high temperatures result from intense metabolic activity by indigenous microorganisms. The middle mesophilic phase (50-65 °C) follows, during which temperatures decrease, allowing heat-resistant microbes to thrive once more. Finally, the finishing phase (23-50 °C) stabilizes both organic matter and biological heat production (Chen et al., 2011) [6] . Adding cow dung slurry to trash during composting significantly enhances the decomposition process and improves compost quality. Cow dung is rich in microbial populations and nutrients, particularly nitrogen and carbon which stimulate microbial activity and accelerate the breakdown of organic matter. It is possible to accelerate decomposition of cane trash by using cellulolytic or lignolytic microorganisms like Trichoderma, Trichurus and Aspergillus spp. (Saravanan and Mahendran, 2003) [27] . Trichoderma spp., common inhabitants of the rhizosphere, besides accelerating decomposition of organic residues can act as biocontrol agents of soilborne plant pathogens (Chet, 1987; Chet et al., 1997; Harman and Lumsden 1990; Harman, 2000) [7,8,17,18] . Trichoderma act as a biocontrol agent that can reduce disease and enhance plant growth under green house or field conditions (Harman and Bjorkman 1998; Ousley et al.,1994) [16,24] . The inoculation of Trichoderma also enhanced iron transport mechanisms from roots to shoots (Yedidia et al., 2001). Production or control of plant hormones is responsible for improving root development, such as auxin, harzionic acids and harzionalide by Trichoderma spp. (Cai et al., 2013, Contreras-Cornejo et al., 2009) [9] . Therefore, instead of relying on environmentally harmful practices like trash burning, it becomes imperative to adopt sustainable alternatives such as composting with the aid of bioinoculants, organic and chemical additives. These approaches not only ensure efficient recycling of sugarcane residues but also enhance soil fertility, reduce dependence on chemical fertilizers and mitigate adverse environmental impacts. Emphasizing such eco-friendly practices will be crucial in improving crop productivity, lowering production costs and safeguarding natural resources for future generations.

Methods

A pot trial experiment was conducted at the farm of Department of Plant Pathology and Agricultural Microbiology, College of Agriculture, Pune during 2024-25 in completely randomized design with seven treatments and three replications. The plastic pots were fixed by digging small pit at experimental site. In each treatment of pot, 10-15 layers of chopped sugarcane trash was filled with chemical additives viz., Mono ammonium phosphate (MAP) @ 5 kg, Diammonium phosphate (DAP) @ 5 kg and Urea @ 10 kg urea mixed in 100 lit. water for per ton of sugarcane trash. These layers are then moistened with filtered 5 litres of slurry made up of cow dung (i.e., 50 g soil + 50 g cow dung for every 1 litre of water). Liquid bioinoculant of Trichoderma spp. (T. asperellum, T. harzianum and T. hamatum) @ 1 lit. each per ton of sugarcane trash was applied in each layer of sugarcane trash. Over the final trash layer, a layer of soil will be spread to a thickness of 15cm and the head is covered. The heap will be moistened once in a week from above and allowed to decompose up to 4 months. The compost material was turned once at 30 days after composting to allow more aeration inside the material. Allowing bottom layer to top and top layer at bottom for uniform composting. The observations on changes in microbial population was estimated at monthly interval through serial dilution technique and pour plate method (Aneja, 2007). Periodical monitoring of decomposition at (0, 5, 10, 15, 30, 45, 60, 75, 90 and 120 days) by measuring temperature with compost temperature probe (Bajiko et al., 2018) [2] and the moisture percent by gravimetric method (Hati, 2021) [19] during composting stages. Effect of liquid bioinoculants, organic and chemical additives on the quality of compost of sugarcane trash including physical properties such as, dark coloration, fine texture, weight at maturity, per cent weight loss at regular intervals were recorded and summarized. The data obtained from different observations were computed statistically by using the standard statistical methods as described by Panse and Sukhatme (1967) [25] for its statistical significance. The data were presented in tabular form with suitable graphical illustrations and figures at appropriate places.

Results and discussion

Periodical CO2 evolution as influenced by use of liquid bio-inoculants, organic and chemical additives for decomposition of sugarcane trash

The data pertaining to the periodical CO2 evolution under aerobic conditions are presented in Table 1 and depicted graphically in Figure 1. The highest CO2 evolution which peaked at 62.33 mg kg -1 d -1 dry matter on the 60 th day, recorded in T5-Spray of 10 kg Urea + 5 kg Di-ammonium Phosphate (DAP) (18:46:0) + Spray of filtered cow dung slurry @ 5 lit. + liquid bioinoculant Trichoderma spp. (T. asperellum, T. harzianum and T. hamatum) @ 1 lit. each per ton of sugarcane trash there after the respiration rate was decreased at 90 and 120 days of composting in respect of various treatments. It was found statistically at par with treatment T6-Application of 8 kg Urea + 10 kg SSP and 1 kg decomposing culture and T4-Spray of 10 kg Urea + 5 kg Mono-ammonium Phosphate (MAP) (12:61:0) + Spray of filtered cow dung slurry @ 5 lit + liquid bioinoculant Trichoderma spp. (T. asperellum, T. harzianum and T. hamatum) @ 1 lit. each per ton of sugarcane trash with total CO2 evolution of 61.63 mg kg -1 d -1 and 60.90 mg kg -1 d -1 , respectively and the lowest CO₂ evolution 34.30 mg kg -1 d -1 in the absolute control (T7). By the end of the composting period (120 th day) CO₂ evolution in all treatments had significantly decreased, with values ranging from 44.07 mg kg -1 d -1 (T5) to 30.87 mg kg -1 d -1 indicating compost stabilization. These observations are supported by Bharadwaj and Gaur (1970), who suggested that greater carbon loss during composting results from intensified microbial activity, influenced by substrate fineness and oxygen availability. during decomposition. Furthermore, Laharia et al., (2019) [20] reported that the respiration rate increased during the initial composting phase up to 60 days due to high microbial mineralization of organic matter, but gradually declined at 90 and 120 days signaling a reduction in microbial activity as compost reached maturity. [32] , who recommended a final C:N ratio of 20-30 especially when combined with microbial inoculation. Similar results were also observed by Goyal et al., (2005) [15] at maturity (90 days of composting), the C:N ratio of the final composted products ranged from 11.7 to 28.3, with the lowest in pressmud and the highest in sugarcane trash plus cattle dung. The study confirms that balanced nutrients and microbial consortia improve composting efficiency, evidenced by a consistent C:N ratio decline. hamatum) @ 1 lit. each per ton sugarcane trash (T4) reaching temperature 49.63 °C and 47.71 °C, respectively. Whereas, least temperature was recorded in absolute control (T7) i.e. 38.28 °C. In the 120 th days of composting, no significant differences were observed among all treatments and was ranged between 35.67 °C to 30.81 °C. This uniformity in final temperatures suggests that all treatments, regardless of their initial thermophilic intensity, approached ambient stabilization levels by day 120. These findings align with Gowda (1996) [14] , who observed that microbial respiration raises compost temperature through oxygen use and heat release, favoring rapid growth of thermophilic microbes (40-70 °C) and faster decomposition. Similarly, Dhapate et al. (2018) [10] reported higher temperatures in sugarcane trash inoculated with cellulolytic fungi compared to uninoculated controls which then gradually decreased up to 120 days. The present study confirms that nutrient supplementation with microbial inoculants sustained elevated thermophilic conditions promoting efficient organic matter decomposition. 4. Most treatments maintaining levels between 43 to 55% during the composting. Among all treatments T5 -Spray of 10 kg Urea + 5 kg Di-ammonium Phosphate (DAP) (18:46:0) + Spray of filtered cow dung slurry @ 5 lit. + liquid bioinoculant Trichoderma spp. (T. asperellum, T. harzianum and T. hamatum) @ 1 lit. each per ton of sugarcane trash, T4 -Spray of 10 kg Urea + 5 kg Monoammonium Phosphate (MAP) (12:61:0) + Spray of filtered cow dung slurry @ 5lit + liquid bioinoculant Trichoderma spp.(T. asperellum, T. harzianum and T. hamatum) @ 1 lit. each per ton sugarcane trash and T6 -Application of 8 kg Urea + 10 kg SSP and 1 kg decomposing culture were significantly retained higher moisture levels ending at 48.00%, 48.20% and 49.50%, respectively. These treatments benefited from the presence of nutrient-rich additives and microbial inoculants, which enhanced organic matter decomposition and helped retain moisture through the release of metabolic water during microbial respiration. These results align with the findings of Misra et al., (2003) [22] who noted that the optimal moisture content for composting ranges between 40% and 65%, with moisture levels above 65% reduce porosity and promote anaerobic conditions leading to unpleasant odours, while levels below 30% can inhibit bacterial activity. Further support comes from Razmjoo et al., (2015) [26] and Bazrafshan et al. (2016) [3] , who reported that a moisture range of 45-50% is ideal for microbial activity and effective composting under aerobic conditions. Whereas, minimum Trichoderma spp. population 15 × 10⁵ cfu/g of compost was observed in absolute control (T7) at 60 days after inoculation. Gradual decline in Trichoderma spp. populations was observed across all treatments at 90 th and 120 th day of composting, as substrate availability reduced and composting progressed toward the stabilization phase and approached maturity. These observations are supported by Dhapate et al., (2018) [10] , who reported that fungal populations in sugarcane trash compost peaked around 60 days due to thermophilic fungi, then declined as compost stabilized. Furthermore, Mahanta et al., (2014) [21] confirmed that Trichoderma harzianum possesses strong lignocellulolytic potential and can effectively break down complex plant residues by producing key enzymes like cellulases and hemicellulases. This explains the high fungal population and efficient decomposition observed in treatments inoculated with Trichoderma. 6 and depicted graphically in Figure 6.

Colour at maturity

Colour change is a qualitative indicator of compost maturity. Most treatments (T1 to T6) resulted in compost with a "Very dark grayish brown" to "Very dark gray" colour, typical of well-decomposed and stabilized organic matter. Notably, "Very dark gray" colour, was observed in T5 -Spray of 10 kg Urea + 5 kg Di-ammonium Phosphate (DAP) (18:46:0) + Spray of filtered cow dung slurry @ 5lit. + liquid bioinoculant Trichoderma spp. (T. asperellum, T. harzianum and T. hamatum) @ 1 lit. each per ton of sugarcane and T6-Application of 8 kg Urea + 10 kg SSP and 1 kg decomposing culture suggesting complete humification and maturity. In contrast, the absolute control (T7) showed a "Light Olive Brown", indicating poor or incomplete decomposition shown below. The results in respect of particle Size (4 mm sieve fraction) of compost was significantly influenced by different treatments shown in Table 6. Among all treatments, the treatment T5 -Spray of 10 kg Urea + 5 kg Di-ammonium Phosphate (DAP) (18:46:0) + Spray of filtered cow dung slurry @ 5lit. + liquid bioinoculant Trichoderma spp. (T. asperellum, T. harzianum and T. hamatum) @ 1 lit. each per ton of sugarcane resulted superior 89.55 g particle size.

However, it was found statistically at par with treatment T6 -Application of 8 kg Urea + 10 kg SSP and 1 kg decomposing culture. The lowest particle size was observed in the absolute control T7 (65.79 g), indicating poor decomposition and coarse compost texture due to the lack of external inputs.

Weight at maturity and per cent loss in weight

Among all the treatment, the treatment T5 -Spray of 10 kg Urea + 5 kg Di-ammonium Phosphate (DAP) (18:46:0) + Spray of filtered cow dung slurry @ 5lit. + liquid bioinoculant Trichoderma spp. (T. asperellum, T. harzianum and T. hamatum) @ 1 lit. each per ton of sugarcane recorded maximum weight at maturity 7.11 kg and total loss in weight i.e. 28.9% and it was statistically at par with treatment T6 -Application of 8 kg Urea + 10 kg SSP and 1 kg decomposing culture showed 7.17 kg weight at maturity and weight loss value 28.3%. While the absolute control T7 showed the 8.95 kg weight at maturity and least weight loss of 10.5%, indicating poor composting efficiency due to the absence of both nutrient and microbial inputs. Similar results were proposed by Dhapate et al., (2018) [10] and Shinde et al., (2024) [28] who reported loss in weight of sugarcane trash during composting.

Treatments integrating with chemical fertilizers, organic additives, and microbial inoculants (especially T5 and T6) significantly improved compost physical quality. These treatments produced darker and finer compost with higher mass reduction, indicating better microbial breakdown and humification.

References

1. Aneja KR. Experiments in microbiology, plant pathology and biotechnology. 4th ed. New Delhi: New Age International (P) Limited; 2007. p.145-156.
2. Bajiko J, Fiser J, Jicha M. Temperature measurement and performance assessment of the experimental composting bioreactor. Eur Phys J Web Conf. 2018;180:2003-2004.
3. Bazrafshan E, Zarei A, Mostafapour FK, Poormollae N, Mahmoodi S, Zazouli MA. Maturity and stability evaluation of composted municipal solid wastes. Health Scope. 2016;5(1):1-9.
4. Bhardwaj KK, Gaur AC. The effect of humic and fulvic acid on the growth, efficiency of nitrogen fixation by Azotobacter chroococcum. Folia Microbiol. 1970;15:364-364.
5. Cai F, Yu G, Wang P, Wei Z, Fu L, Shen Q, Chen W. Harzianolide, a novel plant growth regulator and systemic resistance elicitor from Trichoderma harzianum. Plant Physiol Biochem. 2013;73:106-113.
6. Chen L, De Haro Marti M, Moore A, Falen C. Dairy compost production and use in Idaho: the composting process. Univ Idaho Ext Publ. 2011;CIS1179:1-12.
7. Chet I. Trichoderma: application, mode of action, and potential as biocontrol agent of soilborne plant pathogenic fungi. In: Innovative approaches to plant disease control. 1987. p.137-160.
8. Chet I, Inbar J, Hadar Y. Fungal antagonists and mycoparasites. 1997. p.165-184.
9. Contreras-Cornejo HA, López-Bucio JS, MéndezBravo A, Macías-Rodríguez L, Ramos-Vega M, Guevara-García ÁA, López-Bucio J. Mitogen-activated protein kinase 6 and ethylene and auxin signaling pathways are involved in Arabidopsis root-system architecture alterations by Trichoderma atroviride. Mol Plant Microbe Interact. 2015;28(6):701-710.
10. Dhapate SS, Dilpak SA, Pawar RK. Studies on effect of cellulolytic fungi on decomposition of sugarcane trash. J Pharmacogn Phytochem. 2018;7(15):2975-2977.
11. Gaind S, Nain L. Chemical and biological properties of wheat soil in response to paddy straw incorporation and its biodegradation by fungal inoculants. Biodegradation. 2007;18(4):495-503.
12. Gajalakshmi S, Abbasi SA. Solid waste management by composting: state of the art. Crit Rev Environ Sci Technol. 2008;38(5):311-400.
13. Ghodke SK, Gavit UA, Patil KB, Raskar BS. Effect of in-situ recycling of sugarcane crop residue and its industrial wastes on yield and quality of sugarcane and soil sustainability in Inceptisol. Int J Chem Stud. 2020;8(4):3177-3182.
14. Gowda TKS. Compost making and enrichment techniques. In: Proc Natl Seminar Organic Farming Sustainable Agriculture. Bangalore: Univ Agric Sci; 1996. p.46-51.
15. Goyal S, Dhull SK, Kapoor KK. Chemical and biological changes during composting of different organic wastes and assessment of compost maturity. Bioresour Technol. 2005;96(14):1584-1591.
16. Harman G, Bjorkman T. Potential and existing uses of Trichoderma and Gliocladium. In: Trichoderma and Gliocladium. Vol 2. Enzymes, biological control and commercial applications. 1998. p.229-250.
17. Harman GE, Lumsden RD. Biological disease control. The Rhizosphere. 1990. p.259-280.
18. Harman GE. Myths and dogmas of biocontrol: changes in perceptions derived from research on Trichoderma harzianum T-22. Plant Dis. 2000;84(4):377-393.
19. Hati KM, Somasundaram J, Chaudhary RS. Determination of soil moisture retention field capacity and permanent wilting point. In: Soil analysis. Indian Soc Soil Sci. 2021. p.277-279.
20. Laharia GS, Navale VD, Rathod PH, Jadhao SD, Aage AB. Changes in biochemical properties during decomposition of various crop residues. Int J Chem Stud. 2019;7(5):3383-3386.
21. Mahanta K, Jha DK, Rajkhowan DJ, Kumar M. Isolation and evaluation of native cellulose degrading microorganisms for efficient bioconversion of weed biomass and rice straw. J Environ Biol. 2014;35(4):721728.
22. Misra RV, Roy RN, Hiraoka H. On-farm composting methods. Rome: FAO; 2003. p.1-40.
23. Mohan P, Ponnusamy D. Addressing the challenges of sugarcane trash decomposition through effective microbes. In: Proc Int Conf Food Eng Biotechnol. 2011;9:229-233.
24. Ousley MA, Lynch JM, Whipps JM. Potential of Trichoderma spp. as consistent plant growth stimulators. Biol Fertil Soils. 1994;17:85-90.
25. Panse VG, Sukhatme PV. Statistical methods for agricultural workers. 2nd ed. New Delhi: ICAR; 1967. p.381-400.
26. Razmjoo P, Pourzamani H, Teiri H, Hajizadeh Y. Determination of an empirical formula for organic composition of mature compost produced in IsfahanIran composting plant in 2013. Int J Environ Health Eng. 2015;4(1):3-10.
27. Saravanan A, Mahendran PP. Enriched organic wastes-the challenging perspective in agriculture. In: Short course on eco-friendly recycling of organic and industrial wastes for sustainable soil health. 2003. p.3550.
28. Shinde TB, Borate VA, Chavan SD, Pol VB. Composting of sugarcane trash by using a microbial consortium. Int J Res Agron. 2024;7(4):641-644.
29. Singh A, Sharma S. Composting of a crop residue through treatment with microorganisms and subsequent vermicomposting. Bioresour Technol. 2002;85(2):107111.
30. Yedidia I, Srivastva AK, Kapulnik Y, Chet I. Effect of Trichoderma harzianum on microelement concentrations and increased growth of cucumber plants. Plant Soil. 2001;235(2):235-242.
31. Zhang BG, Li GT, Shen TS, Wang JK, Sun Z. Changes in microbial biomass C, N, and P and enzyme activities in soil incubated with the earthworms Metaphire guillelmi or Eisenia fetida. Soil Biol Biochem. 2000;32(14):2055-2062.
32. Zhengyu J, Liyun Z, Yuanwang L, Xiaqing L, Zhaojun L. Evaluation of composting parameters, technologies and maturity indexes for aerobic manure composting: a meta-analysis. Sci Total Environ. 2023;886:164-180.