EVALUATING SITE SPECIFIC AND REAL TIME NITROGEN MANAGEMENT STRATEGIES FOR HYBRID MAIZE (Zea mays L.)
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Date
2018
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Acharya N.G. Ranga Agricultural University
Abstract
A field experiment was conducted during kharif season, 2017 on sandy
loam soils of Agriculture College Farm, Mahanandi, Acharya N.G. Ranga
Agricultural University, Andhra Pradesh entitled “Evaluating Site Specific and
Real Time Nitrogen Management Strategies for Hybrid Maize (Zea mays L.)”.
The investigation was carried out to study, evaluate and identify suitable site
specific and real time nitrogen management options so as to synchronize N
application with that of crop N demand for achieving higher yield and N use
efficiency in hybrid maize.
The experiment was conducted in randomized block design with eight
treatments replicated thrice. The treatments include recommended fertilizer
dose (T1), soil test based fertilizer application (T2), LCC based approach i.e.,
apply N25 if LCC value < 5 (T3), SPAD chlorophyll meter based approach i.e.,
apply N25 if SPAD value < 50 (T4) and Green Seeker based approach i.e.,
based on NDVI (T5), Farmer Fertilizer Practice (T6), STCR based targeted
approach with a target yield of 8 t ha-1 approach (T7) and Absolute Control
(T8).
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The experimental field was slightly alkaline in reaction, non saline in
nature and low in organic carbon, low in available nitrogen, low in available
phosphorus and high in potassium. The N received by the crop under different
treatments ranged from 180 to 320 kg ha-1 in 3 to 5 splits based on the
treatment demand. With varying nitrogen levels in different treatments,
performance was evaluated in terms of maize grain yield, nutrient uptake, N
use efficiency and B:C ratio. Leaf samples were analyzed for nutrient
composition (N, P, K and micronutrients) at every 10 days intervals up to
tasseling stage, grain and stover yield at harvest and nutrient uptake was
computed. Absolute control received no nitrogen and the highest N dose of
320 kg ha-1 was received in T6 (3 splits). The highest number of split
application of N took place in T3, T4 and T5 (5 splits). LCC, SPAD and Green
Seeker values increased gradually from initial knee high stage to tasseling
stage of the crop.
Nitrogen content in leaves also increased up to tasseling and was
significantly influenced by different N management options. Highest N content
of 3.92 % in leaves was observed in T5 at tasseling. The highest grain yield of
maize (8072 kg ha-1) was recorded in T5 (Green Seeker based NDVI) which
received 215 N kg ha-1 in 5 splits but was found on par with T3 (N25 if LCC
value < 5), T4 (N25 if SPAD value < 50) which received 190 kg N ha-1 in 5
splits, T6 (FFP) that received 320 N kg ha-1 and T7 (STCR approach). Yield
attributes that include cob weight, cob length, number of kernels per row and
number of rows of kernels were higher in T5 which contributed to higher yield
due to effective translocation of photosynthates from source to sink.
Green Seeker, SPAD and LCC values correlated significantly and
positively with N content in leaves and grain yield indicating that simple tools
like Leaf Colour Chart, SPAD chlorophyll meter and Green Seeker can be
effectively used for monitoring leaf N content in maize and there by
rationalizing N application for achieving higher yields. Split application of
Nitrogen based on crop demand is found useful instead of providing large
quantity of nitrogen which is prone to various losses in the soil resulting in low
N use efficiency and lower yields. The benefit - cost ratio was also high in T5
(3.32) followed by T3 (3.05) and T4 (2.92) in these dynamic N management
approaches as compared to other practices evaluated in the study. It is clear
from the study that the LCC, SPAD and Green seeker based nitrogen
application can be recommended rather than blanket application of fertilizers.
The timely and synchronized application of nitrogen as per requirement of crop
at different stages of crop growth can give better yields rather than single
application of fertilizers.
Description
D5737
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