Impact of intensive use of nitrogenous fertilizer on nitrate contamination in groundwater, soil and sugarcane quality in Samastipur district of Bihar
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Date
2022
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Publisher
DRPCAU, PUSA
Abstract
A study was conducted to assess the potential of nitrate-nitrogen (NO3-N)
leaching though soil profile and its contamination in ground water as a function of soil
properties and agricultural activities in the sugarcane growing areas of Samastipur
district in Bihar where, nitrogenous fertilizers were applied intensively years after
years. The effects of heavy nitrogen application on sugarcane quality also estimated.
Total 64 soil samples from four different depths (0-30, 30-60, 60-90 and 90-120 cm),
16 sugarcane samples and 24 groundwater samples and 8 surface water samples were
collected from 8 selected villages in the study area. The soil samples were analysed
for sand, silt, clay, bulk density, pH, EC available nitrogen, phosphorus, potassium
and nitrate- nitrogen (NO3-N) while sugarcane juice were analysed for brix, sucrose,
purity and commercial cane sugar and water samples were analysed for pH, EC, NO3-
N load and major cations and anions concentration. Data on predominant cropping
systems, fertilizer uses were also recorded for the study area.
Nitrate content in soil layers below the root zone indicates significant nitrate
leaching through soil profile. The NO3
-N content in soil had significant positive
correlation with silt content at all the four depths of soil. Nitrate is also positively
correlated with EC (r= 0.519* at 30 cm & 0.520* at 120 cm). It had also positive
correlation with OC (r=0.505*) and available nitrogen (r= 0.701**) at 30 cm depth of
the soils. The negative correlation of brix (%) with N- application rate in soil was
highly significant (r = -0.843**). The correlation coefficient between nitrate and
sucrose (r = -0.904**) indicates that sucrose concentration in juice is significantly
reduced with increasing N- fertilization rate. Similarly, N- application rate was found
to be significantly and negatively correlated with purity (%) and CCS (%) and their
correlation coefficient values are found to be -0.821** and -0.912**, respectively. The
NO3-N load in groundwater samples were low ranging from 1.14 to 4.69 mg L−1 with
only 16.7 % of them contained greater than 4.0 mg L−1 well below the 10 mg L−1, the
threshold limit fixed by WHO for drinking purpose. The content increased with
increasing rate of nitrogenous fertilizer application. The NO3-N load in ground water
also decreased with clay content (r=-0.745*) but increased with increasing nitrate
content (r= 0.909**) of soils. Results thus indicated that the groundwater of the study
area is presently safe for drinking purpose but some anthropogenic activities
associated with intensive cultivation had a positive influence on its loading with
NO3-N.