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Birsa Agricultural University, Ranchi

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Author: Shinde Reshma Bhausaheb × Start date: 2013 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Isolation, Screening of Lignocellulose Decomposer and Its Impact on Crop Residue Decomposition, Soil Properties and Yield of Crops
    (Birsa Agricultural University, Ranchi, 2023) Shinde Reshma Bhausaheb; D.K. Shahi
    In India, the top ten crops generating about 686 Mt of residues are estimated to hold the potential to supply 5.6 Mt of NPK nutrients to the soil. When left on the field, crop residues decompose into different organic substances through the action of various soil microbes over time. The isolation of native fast-degrading microbes from areas and their inoculation can potentially enhance crop residues' decomposition speed and nutrient release process. Considering this hypothesis, an experiment was conducted to study the isolation and screening of lignocellulose decomposer and its impact on crop residue decomposition, soil properties, and yield of crops at the research farm of ICAR-Research Complex for Eastern Region, FSRCHPR, Ranchi, India. Fifteen strains of fungi and six bacteria were isolated as pure colonies from various sources, out of which seven isolated microbial cultures (IMC) were identified as lignocellulose decomposers. IMC 18 and IMC 4 had shown higher enzyme activities for decomposing cellulose and lignin and were identified as Trichoderma viridi and Aspergillus niger. The efficiency of these strains was tested through on-field trials to establish them as potential lignocellulose decomposers. The field experiment was laid out in a factorial randomized block design (FRBD) with two factors, consisting of three crop residues [paddy (C1), black gram (C2), and ragi straw (C3)] and five microbial inoculation treatments [control (T1), A. niger (T2), T. viridi (T3), A. niger + (1%) nitrogen application (T4) and T. viridi + (1%) nitrogen application (T5)] for each crop residue. In total, there were fifteen treatment combinations with two replications each. The decomposition and nutrient release patterns of all three crop residues were studied using litter bag techniques. Among the three types of crop residues, black gram straw exhibited the highest decomposition rate, followed by paddy straw and ragi straw. In treatment T5, where microbial inoculation was applied, over 90% of black gram straw decomposed within six months of field placement, while for paddy and ragi straw, this occurred within eight and nine months, respectively. Contrastingly, in the control treatment (T1) without microbial inoculation, over 90% decomposition of black gram straw occurred in eight months, while for paddy and ragi straw, it took ten and eleven months, respectively. The highest decomposition t99 period of 23.25 months was observed for ragi straw in the control treatment, while the shortest t99 period of 10.55 months was noted for black gram straw in treatment T5. In treatments with microbial inoculation, decomposition rates were 8.5-25% higher compared to the control. The sequence of straw decomposition rates in the microbial treatments followed the order: control < T2 < T3 < T4 < T5. Furthermore, the release rates of nitrogen (N), phosphorus (P), and potassium (K) were higher in the microbial-inoculated treatments compared to those without inoculation. N, P, and K release rates followed the order K > P > N. The application of crop residues led to an increase in available nitrogen (N), phosphorus (P), and potassium (K) in the soil. Treatment C1, involving paddy straw application at 5.0 t ha-1, exhibited the highest available N (264.0 kg ha-1) and P (34.0 kg ha-1). In contrast, treatment C3, with ragi straw at the same rate, showed the highest available K (337.3 kg ha-1). Among microbial treatments, the inoculation of Trichoderma culture with nitrogen supplementation (T5) resulted in a significant rise in available NPK (267.34, 35.99, and 340.73 kg ha-1, respectively) in the soil. Applying crop residues (paddy or ragi straw at 5.0 t ha-1) enhanced the yield of field pea, moong bean, and maize cropping systems by 5-12%. In microbial-inoculated treatments, notably higher grain yields were observed for field pea (4.21-11.7%), moong bean (4.35-11.6%), and maize (4.91-10.39%) compared to the control. Among microbial treatments, T5 demonstrated significantly higher grain yields (10.39-11.7%) and straw yields (7.37-19.67%) across all three crops. The present study illustrated that inoculation of Trichoderma and Aspergillus spp. culture, along with nitrogen supplementation, can be a practical approach for in situ residue management, leading to the proliferation of beneficial microorganisms that hasten the degradation process of crop residues. Adding crop residues (paddy or ragi straw @ 5.0 t ha-1) not only increased the yield of field pea, moong bean, and maize cropping system but also improved the other soil fertility parameters such as organic carbon, available NPK, DTPA-Fe, Mn, Cu and Zn content, soil microbial count and soil enzyme activity like dehydrogenase and FDA. These factors are necessary to achieve sustainable production and minimize soil nutrient depletion. The application of crop residues and inoculation of Trichoderma spp. or Aspergillus spp. and nitrogen supplementation has the potential of this environment-friendly technology for in situ straw management and nutrient sources in the low input cropping system.