Impact of municipal solid waste on soil microbiological properties and wheat (Triticum aestivum L.) growth
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Date
2018
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CCSHAU
Abstract
With rapid growth in population and industrialization, municipal solid waste (MSW)
generation has been escalating day by day. It is a solid residual product, which is generated from the
municipal wastewater treatment plants containing huge quantities of organic matter, micro and macronutrients
and some of the trace elements. The direct application of MSW lead to build up the soil
organic matter and may stimulate the plant growth. However, MSW may contain some heavy metals
and pathogens. While some heavy metals are necessary for the living organisms in trace amounts, most
are harmful and hazardous in high quantities. The repeated application of MSW may result in the
accumulation of these heavy metals to such an extent, which may prove detrimental to the plants and
microbes. In the present study, two different municipal solid wastes were collected from sewage
treatment plants situated at CCS HAU Hisar (MSW1) and Hisar city (MSW2) Haryana and analysed for
organic matter, different plant nutrients (total N, P, C and K) and heavy metal concentrations. The
heavy metal contents were below the EU permissible limits. The DTPA extractable forms of heavy
metals were more in solid waste collected from CCS HAU Hisar (MSW1) as compared to the solid
waste collected from Hisar city (MSW2). These MSW were added to the soil at the rates of 5, 10, 20,
30 and 50 t/ha and incubated under laboratory conditions upto 90 days. Sub samples were drawn at
different time intervals and analysed for different chemical and microbiological properties of soil.
There was significant increase in soil organic C, total N and EC over control. Soil organic C gradually
declined with incubation time, however no significant difference was observed in total N after 90 days.
The DTPA extractable forms of heavy metals (Pb) increased upto 15 and (Ni, Cr, Cu and Cd) 30 days
of incubation and then declined with further incubation of 90 days. Microbial biomass C, N, soil
dehydrogenase, alkaline phosphatase, urease and cellulase activities, increased significantly in soil
amended with different levels of both MSW. Total bacterial and E. coli count increased with increasing
levels of solid waste throughout the 90 days of incubation. Fungal and phosphate solubilizing bacterial
count increased upto 30 days, however, population of Azotobacter increased with increasing
application rates of MSW1 and MSW2, but no significant difference was observed with incubation
period. Addition of the MSW1 and MSW2 to the soil promoted the functional diversity (catabolic
potential) of the soil microbial population. Under pot house conditions the dry matter yield and uptake
of N, P, K by wheat crop increased significantly with increasing application rates of MSW1 and MSW2
from 5 to 50 t/ha, over the control. However, the yield and nutrient uptake by mustard crop increased
with application of MSW upto the level of 20 and 30 t/ha of MSW1 and MSW2, which further declined
with 50 t/ha of solid waste. The accumulation of heavy metals (Cr, Cd, Ni and Pb) in Indian mustard
crop increased significantly with increasing levels of MSW1 and MSW2 and was more than wheat crop.
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