Effects of some industrial organic wastes on maize grain yield and some soil properties
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Date
2003
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Sokoine University of Agriculture
Abstract
A study was conducted to evaluate paper sludge and pyrethrum marc as alternative
sources of plant nutrients using maize as a test crop. The study was carried out at
Magadu Morogoro, Tanzania. Kaaya (1989) classified the soil of Magadu as Oxic
Haplustult. Laboratory analyses revealed the soil to be clay, compacted and acidic
with low CEC (11.2 Cmol(+) kg'1) Total nitrogen, (0.09 %) exchangeable Ca (1.77
Cmol (+)kg‘‘ ) and Na (0.67 Cmol (-j-)kg'1 were low, exchangeable K (0.69 Cmol
(-i-)kg'1) and Mg (1.51 Cmol (-r)kg'1 were high, extractable Fe (46.48 mg kg'1) and Mn
(70.06 mg kg'1) were very high while Cu (1.14 mg kg'1) and Zn (0.51 mg kg'1) were
adequate for plant growth. Four rates of paper sludge and pyrethrum marc (0, 10, 20,
and 30 tons ha'1) on air-dry basis were applied to soil in a randomized block design.
The wastes were characterized before incorporation into the soil. Paper sludge and
pyrethrum marc were alkaline and acidic in reaction respectively. Paper sludge had
high C/N (37.7) C/P (245) and Ca/Mg (105.22) ratios .The high C/N and C/P ratios
mean that biological immobilization of nitrogen and phosphorus would be the major
limiting factors for this waste to be used as a source of plant nutrients. High Ca/Mg
ratio indicates that paper sludge can be used as a liming material. Paper sludge had
lower sodium adsorption ratio (SAR) (0.22) as compared to pyrethrum marc (0.62).
This suggested that sufficient Ca and Mg are present to counteract the negative
effects of sodium. Levels of Fe (333.4) Mn (543.71) Cu (21.00) and Zn (42.9) for
paper sludge and 107.55; 901.85; 14.4 and 51.00 respectively for pyrethrum marc,
were well within the limits for environmental pollution. Maize grain yield in plots
amended with pyrethrum marc increased from 0.64 to 3.33 tons ha’1 with increasing
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rate of pyrethrum marc while in plots treated with paper sludge grain yield decreased
from 1.43 to 0.52 tons ha"‘as the rate of application of paper sludge increased. The
Increasing the rates of the wastes ameliorated the bulk density from 1.50 tol.38 mg
cmrivas associated with decrease in soil bulk density. For pyrethrum marc treated
plots, soil pH, OC, total N, extractable P and exchangeable Ca, Mg, and Na and CEC
increased with increasing rates of the waste. Cu and Fe were significantly lowrelative
to the control, and Zn was higher than the control. Soil pH, exchangeable Ca
and CEC of the plots amended with paper sludge increased with increasing rates of
the material from 5.28; 2.61; 10.57 to 7.7914.74; 14.20 respectively. Increasing the
rates of paper sludge had a negative effect on exchangeable Mg, K, Na, and
extractable P. Total nitrogen and organic carbon were not statistically different from
for the lowest rate and 0.81 mgkg'1 for the highest rate of paper sludge). Zn was not
statistically different compared to the control, and Fe was significantly lower than the
control. Both wastes alleviated Al and Mn concentrations remarkably
Description
Dissertation
Keywords
Organic wastes, Maize grain, Soil properties, Paper sludge, Pyrethrum marc