Microbial interventions for composting of organic and lignocellulosic waste
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Date
2020
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Punjab Agricultural University, Ludhiana
Abstract
Composting of paddy straw (PS) and vegetable waste (VW) was carried out by using different
microbial inoculants. Four microbial treatments were designed namely fungal consortium
(Aspergillus, Trichoderma), fungal cum bacterial consortium (Aspergillus, Trichoderma,
Bacillus, Pseudomonas, Azotobacter, Delftia) and two commercial preparations namely
Waste Decomposer and Kayakalp. Initially, aerated bins were used for composting of three
substrate combinations- Set I (100% PS), Set II (50% PS + 50% VW) and Set III (25% PS +
75% VW) @ 7 kg dry weight of substrate and 15% inoculum per bin with an uninoculated
control per Set. However, final C:N ratios were much above acceptable levels and only
inoculated treatments of Set II showed Germination Indices value of >80%. To improve the
composting process, pit composting was carried out at Soil Research Farm using pits of 1.5 m
X 1.2 m X 0.3 m dimensions located at 30.9º N, 75.8ºE. Two new substrate combinations -
40% PS+60% VW (Set I) and 70% PS+30% VW (Set II) were taken @ 40 kg per pit and 15%
inoculum from February to April 2019. In Set I, after 90 days, lowest C% (29.33), highest
N% (1.85) and lowest C:N ratio (15.85) were obtained with fungal cum bacterial consortium.
In Set II, after 90 days, lowest C% (29.24), highest N% (1.48) and lowest C:N (19.76) were
obtained with fungal cum bacterial consortium. After a curing period of 30 days, Set I
inoculated with fungal cum bacterial consortium proved to be the best with pH of 8.19,
electrical conductivity of 1.52 dS m-1, moisture-45%, carbon-29.13%, nitrogen-1.86%,
phosphorus-0.44%, potassium-4.06%, C:N ratio-15.66, volatile solids-52.22%, ash-47.78%,
crude proteins-7.87%, neutral detergent fibre (NDF)-56.40%, acid detergent fibre (ADF)-
36.60%, hemicellulose-19.80% and a germination index of 121.29%.