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Effect of nitrogen
application through urea and Azolla on yield, nutrient uptake of rice
and soil acidity indices in acidic soil of Meghalaya
Sanjay-Swami* and
S. Singh
School of Natural
Resource Management, College of Post Graduate Studies in Agricultural
Sciences, Central Agricultural University,
Umiam-793 103,
India
*Corresponding Author Email : sanjayswamionline@gmail.com
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Abstract
Aim:
To investigate the effect of nitrogen application through urea and Azolla
on yield, nutrient uptake of rice (Oryza sativa L.) cv. Shasharang and
to assess the improvement in soil acidity indices in acidic soil of
Meghalaya.
Methodology: A field experiment was conducted with six treatments
viz., control (T1), Azolla incorporation @ 1.6 tonnes ha-1
(T2), 30 kg N ha-1 through urea (T3), 60 kg
N ha-1 through urea (T4), 30 kg N ha-1
through urea + Azolla incorporation @ 1.6 tonnes ha-1 (T5)
and 60 kg N ha-1 through urea with Azolla incorporation @
1.6 tonnes ha-1 (T6). The experiment was laid out in
RBD and replicated four times. The physico-chemical properties of the
experimental soil were pH 5.1, SOC 1.75 percent, available N, P and K as
288.62, 17.23 and 201.46 kg ha-1, respectively.???
Results: The application of 60 kg N ha-1 through
urea along with Azolla incorporation @ 1.6 tonnes ha-1 (T6)
recorded highest dry matter i.e. 58. 15 g hill-1 at maturity of
rice. Similarly, 60 kg N ha-1 through urea with Azolla
incorporation @ 1.6 tonnes ha-1 produced highest grain and straw
yield i.e. 4.2 t ha-1 and 7.68 t ha-1 followed by T5
and T4. The magnitude of increase in N, P and K concentration and
uptake in grain was 28.57, 97.02; 26.09, 84.21 and 15.69, 76.47 percent in T6
over T1. The analysis of soil acidity indices indicated that highest
improvement in pH was observed in T2 over all other treatments. Further, pH
increased significantly in the treatments receiving Azolla incorporation (T2,
T5 and T6) compared with the sole application of
urea/control (T1, T3 and T4). The
exchangeable calcium and magnesium (meq 100 g-1), CEC (meq 100 g-1)
and base saturation percentage also showed the same trends and the highest
values were observed as 1.92, 7.90 and 24.30 in T2. However, in
contrast to this, the lowest values of exchangeable aluminium, exchangeable
acidity and acidity saturation percentage were observed in T2
indicating that the sole application of Azolla improved soil acidity
indices.
Interpretation: It may be concluded from the present
study that Azolla-urea nitrogen system may be suitable for getting
optimum production of rice under tropical conditions and improving soil
acidity indices because of its ability to fix atmospheric nitrogen.
Key
words:
Azolla
incorporation, Integrated nutrient management, Rice yield, Soil acidity
indices
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