Citation
Mostofi, Nooshin
(2009)
Nitrate Leaching in Soils Treated With Activated Sludge, Cattle Manure and Chemical Fertilizers.
Masters thesis, Universiti Putra Malaysia.
Abstract
Nitrogen fertilizers have been recognized as an important factor in crop’s yield level,
however more application of N fertilizers in the soil have some adverse effects on
environment and especially on ground water contamination. Perception and
recognition the factors influencing nitrate transport through soil profile is helpful for
fertilizer management to minimize adverse impacts on environment and nitrate
leaching below the root zone. In this study, 15 large cylindrical lysimeters with 1 m
height and 0.56 m diameter were filled with clay and sandy loam soil and planted
with maize to investigate nitrate leaching under different types of N-fertilizer;
activated sludge (20 ton/ha), cattle manure (40 ton/ha) and chemical fertilizer
(containing 70 kg N/ha). Also 3 lysimeters with 1.4 m height were used to
investigate the effect of soil depth in nitrate leaching in sandy loam soil. Totally the
study involved nine treatments. Nitrate concentrations in the soil and drainage water
samples were analyzed by spectrophotometer method and nitrate mass were
calculated in irrigation water, soil and drainage water. Crop production for different treatments has been compared too. The nitrate-N concentrations were higher than 10
mg N/L (the maximum acceptable concentration) in 60% of the observations for
OFcl. The Nitrate-N concentrations were higher than 10 mg N/L in 48 and 51% of
the samplings for the CFcl and OFcl treatments, respectively. The Nitrate-N
concentrations were almost always lesser than 10 mg/L in the lysimeters containing
sandy loam soil. Results illustrate nitrate leaching from activated sludge and organic
fertilizer in clay loam soil was significantly greater than the other treatments (110
kg/ha and 229 kg/ha respectively). Among all treatments of this study organic
manure in clay loam soil had the greatest nitrate accumulation in soil (15.17 mg/kg)
and chemical fertilizer in sandy loam soil had the least (8.56 mg/kg). Experimental
results also showed that manure application could result in NO3
--N accumulation
increase in the deeper soil profiles compared with mineral fertilization and activated
sludge. The results demonstrate that nitrate, from the activated sludge and chemical
fertilizers, transported through the soil profile is more than the organic manure after
the 75 cm depth, and the accumulation of organic fertilizer is mostly 60 to 90 cm
depth from the soil surface.
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