EFFECT OF LONG -TERM APPLICATION OF ORGANIC MANURES ON SOIL ORGANIC MATTER FRACTIONS AND PRODUCTIVITY OF RAINFED GROUNDNUT (Arachis hypogaea L.)
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Date
2017
Authors
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Acharya N.G. Ranga Agricultural University
Abstract
The present study entitled “Effect of long-term application of
organic manures on soil organic matter fractions and productivity of
rainfed groundnut (Arachis hypogaea L.)” was taken up in long term
experiment on going since 2007 at Regional Agricultural Research Station,
Tirupati, Acharya N.G. Ranga Agricultural University. The present study
was carried out during kharif, 2016 with a prime objective of monitoring the
changes in soil organic matter fractions as influenced by long term
application of organic manures. The experiment has 6 treatments each
replicated four times in a randomized block design. The treatments include
T1: Control (no manure and fertilizers), T2: RDF (20 Kg of N ha-1, 40 Kg of
P2O5 ha-1, 50 K2O Kg ha-1), T3 : Vermicompost @ 2.5 t ha-1: T4 : Poultry
manure @ 4 t ha-1 T5: Farm yard manure @ 10 t ha-1: T6 : Press mud cake @
10 t ha-1
.
Soil samples were collected from each treatment at 0-15 cm before
sowing and at harvest of crop and analyzed for soil organic matter fractions
physico-chemical, chemical characters, and crop yield at harvest was
recorded.
Among the physico-chemical properties soil EC and organic carbon
was significantly influenced by organic manures but soil pH showed non
significant variation. The major nutrients (N, P and K) showed significant
variation among the treatments, where highest values were observed in
organic manures compared to control and RDF. The secondary nutrients
(Ca, Mg and S) and micronutrients (Zn, Fe, Mn and Cu) also followed
similar trend of increasing contents with organic manure application. It was
further observed that all soil nutrient contents increased at harvest under
RDF and organic manures application but decreased in control treatment
compared to status of before sowing of crop.
Humic acid content in soil before sowing and harvest of the crop was
significantly varied in organic manure treatments. Before sowing humic acid
was ranged from 0.25 to 0.92 g kg-1 while at harvest it was ranged from 0.23
to 1.26 g kg-1. Among the treatments FYM recorded highest values followed
by pressmud cake treatment.
Oxygen containing functional groups (total acidity, carboxyl and
phenolic groups) of humic acid were increased with application of various
organic manures. Before sowing total acidity was ranged from 4.2 to 8.9
me g-1, carboxyl group ranged from 2.2 to 3.4 me g-1 and phenolic groups
ranged from 2.0 to 5.7 me g-1. At harvest of crop total acidity was ranged
from 3.4 to 10.1 me g-1, carboxyl groups ranged from 2.2 to 3.4 me g-1 and
phenolic groups ranged from 2.0 to 5.7 me g-1. The contribution of carboxyl
groups towards per cent of total acidity before sowing of crop was ranged
from 33.72 to 57.41 per cent and phenolic groups ranged from 42.59 to
66.28 per cent, while at harvest carboxyl group contribution ranged from
32.22 to 52.94 per cent and phenolic groups 47.06 to 67.78 per cent.
E4/E6 ratio of humic acid in soils under various organic manures
treatments was significantly varied. Before sowing E4/E6 ratio was ranged
from 4.5 to 5.19, while at harvest it was ranged from 3.45 to 5.63. E4/E6
ratio was decreased from +13.1 to -23.3 per cent from sowing to harvest of
the crop.
Potentiometric titrations curves of humic acid extracted from soils of
various treatments before sowing and harvest of crop are similar and
sigmoidal in nature with each other indicating the apparent monobasic and
had a single break indicating weak acid polyelectolytic character of humic
acid.
Conductometric titration curves of humic acid extracted from soils of
various organic manure treatments before sowing and at harvest of crop
were similar in nature indicating weak acidic character of humic acid.
UV-spectral characteristics of humic acid extracted from soils of
various treatments before sowing and at harvest of crop were almost similar
in nature indicating these are featureless with a decreasing optical density
with increase in wavelength. These are steeper in nature which indicated
more aromatic character of humic acid.
The mean values of NPK content in plant at harvest were 1.53 %,
0.36 % and 1.18 % respectively. The N uptake ranged from 33.71 to 64.29
kg ha-1, P uptake ranged from to 8.92 to 20.28 kg ha-1, K uptake was ranged
from 23.17 to 69.04 kg ha1
. The pod yield of groundnut crop at harvest was
significantly varied with different manure treatments ranged from 1188 to
1531 with a mean value of 1417 kg ha-1. Haulm yield of groundnut was
ranged from 3070 to 4315 with a mean value of 3756 kg ha-1
.
The correlation studies before sowing revealed that humic acid
content was significantly correlated with total acidity (0.993**), carboxyl
groups (0.812*) and phenolic-OH groups (0.960**). Total acidity was
positively correlated with phenolic-OH groups (0.984**), P uptake (0.842*).
A positive and significant relation was observed between N uptake and pod
yield (0.957**) between P uptake and phenolic-OH groups (0.887*) and K
uptake showed significant relation with phenolic-OH groups (0.873*) and P
uptake (0.951**). At harvest also humic acid content showed positive
correlation with total acidity (0.945**), phenolic-OH groups (0.938**) and
P uptake (0.823*).Total acidity showed positive significant relation with
carboxyl groups (0.832*), phenolic-OH groups (0.983**), N uptake
(0.843*), P uptake (0.858*) and K uptake (0.855*). N uptake was positively
significantly correlated with carboxyl groups (0.846*), yield (0.957**).A
positive and significant relation was also observed between P uptake and
phenolic-OH groups (0.896*) and between K uptake and phenolic-OH
groups (0.908*) and P uptake (0.951**).
Description
D5534
Keywords
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