EFFECT OF SEWAGE SLUDGE ON TOMATO (Lycopersicon esculentum L.)
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Date
2014
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ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY, RAJENDRANAGAR, HYDERABAD
Abstract
Sewage sludge used in present study was analyzed in the laboratory following
standard procedures before studying its effect on growth and yield quality in tomato. The
results revealed that the sewage sludge was slightly acidic in reaction with a pH of 6.50, EC
of 5.30 dS m-1, total organic carbon content of 28.35 per cent. Total N, P and K contents of
sewage sludge were 1.68, 0.78 and 0.56 per cent, respectively. The triacid extractable zinc
in sewage sludge was 25.93 mg kg-1 while, the diacid extractable heavy metals viz., Cd, Co,
Ni and Pb were 0.53, 0.57, 1.08 and 6.02 mg kg-1, respectively and are within the
permissible limits as per the standards of USEPA.
Pot culture experiment was conducted using medium textured slightly alkaline red
soil to study the effect of sewage sludge on soil properties, crop growth, nutrients and
heavy metals uptake, yield, quality of yield and other important parameters of tomato. The
present study entitled “Effect of Sewage Sludge on Tomato (Lycopersicon esculentum L.)”
was carried out during late kharif, 2012 at green house farm of the Department
of Horticulture, College of Agriculture, ANGRAU, Rajendranagar, Hyderabad. The
experiment was laid out in Completely Randomized Design (CRD) with three
replications.There were seven treatments consisting of T1 (20% sewage sludge),
T2 (40% sewage sludge), T3 (60% sewage sludge), T4 (80% sewage sludge), T5 (100%
sewage sludge), T6 (RDF - Inorganic N, P and K @ 100, 50 and 50 kg ha-1, respectively)
and T7 (Control, no sewage sludge).Inorganic N, P and K were supplied through urea,
single super phosphate and muriate of potash, respectively as per recommended dose.
The volume of each pot was made up to 6 kg on weight basis with sewage sludge +
soil as per treatment schedule. Necessary care was taken to protect the crop from pests and
diseases. Three sets of pots were arranged for each treatment in each replication. The first
set of plants were collected from pots at vegetative stage (30 DAT), second set of plants
were collected at mid stage (45 DAT) and third set of plants were collected at harvesting
stage (90 DAT) for necessary analysis. Plant parameters like plant height, number of leaves, number of branches, leaf area, chlorophyll content and dry matter production were
recorded at different growth stages .The tomato fruit samples were analyzed for lycopene
content, ascorbic acid, total soluble solids, fruit pH, and titrable acidity, while the plant
samples were analysed for Pb, Co, Ni and Cd uptake in tomato plant. Soil samples were
analyzed for pH, EC, OC, N, P, K, Zn, Pb, Ni, Co and Cd.
There were significant variations in pH and EC of soil samples at all the stages
among different treatments of sewage sludge. Significantly highest organic carbon
was observed in 100% sewage sludge treatment (28.35%) followed by 80% sewage
sludge (24.4%) similar to pH and EC. Availability of N, P, K, Zn, Pb, Co, Ni and Cd in soil
at all stages of observation indicated that the availability of nutrients and concentration of
heavy metals increased with increase in sewage sludge application rates and advancement
in crop age. The available N content in soil exhibited low rating while, P and K content in
soil exhibited high and medium rating respectively. The heavy metals viz., Pb, Ni, Co
and Cd content in soil at all stages were within the maximum permissible limits as per
WHO standards. Observation of potting mixture temperature showed that the temperature
increased with increase in sewage sludge application rates.
Significantly maximum plant height, number of branches, number of leaves per
plant and dry matter production were recorded in 100% sewage sludge in tomato at all
stages of observation. Significantly maximum titrable acidity (0.254 %) and fruit pH (4.57)
were obtained in 100% sewage sludge treatment (T5),while maximum lycopene content
(8.23 mg/100g), ascorbic acid (36.33 mg/100g) and total soluble solids (6.210Brix) was
observed in 80% sewage sludge treatment (T4).
The uptake of major nutrients viz., N, P, K and Zn by plants of tomato was linearly
increased with increase in sewage sludge application rates. Significantly highest and lowest
uptake of these nutrients was noticed, respectively in treatment of 100% sewage sludge
application and Control (T7).
The uptake of Cd and Ni was beyond the maximum permissible limits in 80%
sewage sludge and 100% sewage sludge in tomato plants. But, Co uptake was beyond the
maximum permissible limits only in 100% sewage sludge. In contrast, the uptake of Pb by
plants was within the maximum permissible limits in all treatments. The above study
indicates that, the application of sewage sludge is highly beneficial due to more availability
of major nutrients, micronutrient and organic carbon and enhanced growth, yield and
quality of tomato. However, further study is required to consolidate the results.
Description
Keywords
SEWAGE, SLUDGE, TOMATO