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The Journal of Research ANGRAU

Contents of 41(1) 2013 - acharya ng ranga agricultural university

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LAKSHMI et al<br />

Changes in C/N ratio during<br />

vermicomposting and conventional composting<br />

<strong>The</strong> data presented in Table 1 and 2 revealed<br />

that the C/N ratio <strong>of</strong> cane trash, weeds, vegetable<br />

market waste and paddy straw at 15 days <strong>of</strong><br />

vermicomposting was 57.74:1, 25.69:1, 20.43:1 and<br />

72.33:1, respectively. At the end <strong>of</strong> vermicomposting<br />

i.e at 60 days the C/N ratio was further reduced to<br />

21.60:1,12.70:1,11.34:1 and 21.57:1 in cane trash,<br />

weeds, vegetable market waste and paddy straw,<br />

respectively. Where as in conventional composting<br />

the C/N ratio at 15 days was 57.02:1, 24.87:1, 20.16:1<br />

and 68.87:1, respectively and 60 days after<br />

composting the reduction was 34.63:1, 16.56:1,<br />

14.19:1 and 36.08:1 and at the end <strong>of</strong> composting<br />

i.e. at 110 days it was further reduced to 24.71:1,<br />

13.76:1, 12.73:1 and 24.89:1 in cane trash, weeds,<br />

vegetable market waste and paddy straw,<br />

respectively. In both the composting methods paddy<br />

straw recorded the highest C/N ratio while vegetable<br />

market waste exhibited lowest C/N ratio, however<br />

the percent decrease was more in vermicomposting<br />

than conventional composting in a particular period<br />

<strong>of</strong> time (Fig.1 & 2).<br />

<strong>The</strong> decrease in C/N ratio during<br />

vermicomposting was due to respiratory activity <strong>of</strong><br />

earthworms and microorganisms and increase in<br />

nitrogen by mineralization <strong>of</strong> organic matter and<br />

excretion <strong>of</strong> nitrogenous wastes. Similar results were<br />

reported by Alok Bhardwaj (2010). <strong>The</strong> reduction in<br />

carbon and lowering <strong>of</strong> C/N ratio in the<br />

vermicomposting and conventional composting could<br />

be achieved either by the respiratory activity <strong>of</strong><br />

earthworms and microorganisms or by increase in<br />

nitrogen by microbial mineralization <strong>of</strong> organic matter<br />

in combination with addition <strong>of</strong> the worm’s nitrogenous<br />

wastes through their excretion. <strong>The</strong> rate <strong>of</strong> reduction<br />

<strong>of</strong> C/N ratio was high during vermicomposting than<br />

conventional composting. <strong>The</strong> duration <strong>of</strong><br />

vermicomposting varied from 55 to 60 days for<br />

various organic residues under study, while it took<br />

almost 110 days for conventional composting (Auldry<br />

et al., 2009). During vermicomposting given optimum<br />

conditions <strong>of</strong> temperature and moisture, earthworms<br />

feed on organic component <strong>of</strong> organic residues which<br />

is ground into smaller particles in their gizzard. Later<br />

on the enzyme activity in the intestine brings about<br />

rapid conversion <strong>of</strong> cellulose and protenaceous<br />

materials. This may account for reduced time in<br />

vermicomposting than conventional composting.<br />

Changes in Humic Acid content (%)<br />

during vermicomposting and composting<br />

<strong>The</strong> humic acid production increased with progress<br />

<strong>of</strong> decomposition in both the composting methods.<br />

<strong>The</strong> increase in humic acid content in<br />

vermicomposting from 15 to 60 days varied from 7.50<br />

to 9.85 % in cane trash, 8.12 to 10.40 % in weeds,<br />

9.00 to 10.85 % in vegetable market waste and 7.12<br />

to 9.10 % in paddy straw. At the end <strong>of</strong><br />

vermicomposting significant increase in humic acid<br />

content (10.40 %) was recorded in vegetable market<br />

waste than cane trash and paddy straw, however<br />

vermicomposting <strong>of</strong> weeds recorded on par result<br />

(10.40 %) with vegetable market waste, while<br />

significantly lowest humic acid (9.10 %) was recorded<br />

in paddy straw. At the end <strong>of</strong> conventional composting<br />

i.e 110 days high humic acid content <strong>of</strong> 10.22 %<br />

was observed in vegetable market waste, while<br />

minimum content <strong>of</strong> 9.75 % was recorded in cane<br />

trash. Vegetable market waste recorded 20 & 25 %<br />

increase <strong>of</strong> humic acid content from initial to maturity<br />

in vermicomposting and conventional composting,<br />

respectively.<br />

<strong>The</strong> humic acid production increased with<br />

incubation in both the composting methods and in all<br />

the treatments, Xiaowei et al. (2010) observed that<br />

increasing levels <strong>of</strong> humic acid represent high degree<br />

<strong>of</strong> humification. Humification was found to be<br />

dependent on biochemical characteristics and<br />

composition <strong>of</strong> raw material. <strong>The</strong> high humic acid<br />

content during vermicomposting implies good quality<br />

and maturity <strong>of</strong> compost. Vegetable market waste<br />

recorded highest humic acid content (10.85 %)<br />

followed by weeds (10.40%), cane trash (9.85 %,)<br />

and rice straw (9.10 %) during vermicomposting. This<br />

was probably due to variation in the amount,<br />

composition and differential degradation <strong>of</strong> lignins<br />

(Tejada, 2009) (Fig.3 & 4)<br />

Changes in Fulvic Acid content (%)<br />

during vermicomposting and composting<br />

21

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