Influence of Long Term Nitrogen and Potassium Fertilization on the Biochemistry of Tea Soil

Influence of Long Term Nitrogen and Potassium Fertilization on the
Biochemistry of Tea Soil
Keywords:
Soil enzymes, urease, cellulase, Tea, Soil pH, nitrogen and potassium
fertilizers
ABSTRACT:
As the tea plantation in hilly tracts are located in slopes, the management of
fertilizer regimes is somewhat challengeable due to leaching which in turn affect the
quality of tea soil. In light of this fact the present study was focused to determine the
quality of tea soil in terms of the evaluation of certain physical and biological
characteristics as influenced by various dosage of fertilizer applications. The impact of long
term nitrogen and potassium fertilization on biochemical characteristics and microbial
activities in tea soil has been analyzed in the present study. Different sources and rates of
nitrogen (ammonium sulphate and urea), and potassium (muriate of potash) were tested
at two soil depths (0-10 cm and 10-20 cm) and for two seasons (premonsoon and
monsoon). The acidic tea soil was further acidified with nitrogen application and the
extent of acidification varied with the fertilizer type and season. Soil respiration rates were
higher in 0-10 cm soils and were positively related to soil nitrogen and potassium
concentrations. Among the soil enzymes analyzed, urease activity exhibited different
trends in the two soil depths at different seasons. Urease activity tended to increase with
increasing potassium application rates, whereas higher cellulase activity was associated
with lower nitrogen application rates. This study clearly indicates that the soil quality
depends on the fertilizer application rates and season.
124-135 | JRA | 2012 | Vol 1 | No 2
This article is governed by the Creative Commons Attribution License (http://creativecommons.org/
licenses/by/2.0), which gives permission for unrestricted use, non-commercial, distribution and
reproduction in all medium, provided the original work is properly cited.
www.jagri.info
Journal of Research in
Agriculture
An International Scientific
Research Journal
Authors:
Thenmozhi K1
, Manian S2
and Paulsamy S1
.
Institution:
1.Department of Botany,
Kongunadu Arts and Science
College, Coimbatore
641 029, Tamil Nadu, India.
2. Department of Botany,
Bharathiar University,
Coimbatore 641 046, Tamil
Nadu, India.
Corresponding author:
Thenmozhi K.
Email:
thenmozhi_05@yahoo.co.in
Phone No:
+91- 9942474703.
Web Address:
http://www.jagri.info
documents/AG0029.pdf.
Dates:
Received: 14 Sep 2012 Accepted: 01 Oct 2012 Published: 06 Oct 2012
Article Citation:
Thenmozhi K, Manian Sand Paulsamy S.
Influence of Long Term Nitrogen and Potassium Fertilization on the Biochemistry of
Tea Soil.
Journal of Research in Agriculture (2012) 1(2): 124-135
Original Research
Journal of Research in Agriculture
JournalofResearchinAgriculture An International Scientific Research Journal

INTRODUCTION
Tea (Camellia sinensis (L.) O. Kuntz), a
perennial shrub, cultivated in acid soil yields one of the
most popular non-alcoholic beverage tea which is
consumed world-wide for its taste, aroma and health
effects. South India contributes about 24% of India’s
total tea production. Being a foliage crop, nutrient
requirements for commercial tea production are
particularly high. Nitrogen and potassium are the two
major nutrients of tea without which, commercial
production levels are difficult to achieve (Verma, 1993;
Verma et al., 2001). In south Indian tea gardens, nitrogen
and potassium fertilizers are always applied in
combination. There are three different sources of
nitrogen, namely ammonium sulphate, urea and calcium
ammonium nitrate. However, the choice of potassium is
confined to muriate of potash. This soil management has
potential impact upon soil biological quality. Nitrogen
fertilizers when used on a regular basis tend to acidify
soil. Further, long-term nitrogen fertilization has been
shown to affect the distribution and the amount of
organic carbon, soil microbial biomass and soil enzyme
activities (Darusman et al., 1991; Mc Andrew and
Malhi, 1992). Thus fertilizers as nutrient sources may
have beneficial influence on plants; however, there may
be adverse effects especially on microorganisms, as a
result of soil acidification.
Enzymes catalyze all biochemical reactions and
are an integral part of nutrient cycling in soil.
Investigations are often limited to few enzymes to show
that agricultural management practices affect enzyme
activity (Dick, 1994). A wide range of enzymes have not
been systematically investigated for their potential to
reflect short and long-term soil management effects in
relation to soil quality.
Although the effect of combined application of
nitrogen and potassium fertilizers on biochemical
characteristics of tea is well reported (Venkatesan and
Ganapathy, 2004; Venkatesan et al., 2005), its effect on
soil physico-chemical and biological characteristics are
scarce (Venkatesan et al., 2004). Increasing evidence
indicates that soil biological parameters may hold
potential as early and sensitive indicators of soil health.
Microbial characteristics of acid tea soils are reported to
be qualitatively different from normal acid soils
(Nioh et al., 1993). The objective of the study was to
evaluate the long - term impact of fertilizer application
on physico-chemical and microbiological properties of
selected soil in an experimental tea field receiving
fertilizer treatment since 1994. The selection of
biological response variables was based upon their
relationship to soil function. The soil microbial
community inhabits an environment responding to
physical, chemical or biological perturbation. Soil
biological properties were chosen to represent the soil
environment in which the organism must exist (soil
organic matter and moisture), the microbial community
itself (soil respiration) and biochemical activities of these
populations (soil cellulase and urease activity). These
biochemical activities were chosen to be a representative
of nutrients that influence plant production.
MATERIALS AND METHODS
Experimental site and design
The experimental site was located at United
Planters Association of Southern India (UPASI) Tea
Research Foundation at Anamallais (10°30’N and
77°0’E, at 1050 m a.s.l.), southern India. The climatic
data collected from UPASI Tea Research
Institute - Meterological station, Valparai for the past 20
years showed that the site is experiencing an average
annual rainfall of 1100 mm and the temperature range of
11-29°C. The investigation was carried out in the long
term fertilizer trial plots (10m x 10m) established in 1994
using tea clone SA 6 with 100 bushes/ plot. The duration
of the study period was one year from Nov. 2010 to
Oct. 2011.
125 Journal of Research in Agriculture (2012) 1(2): 124-135
Thenmozhi et al.,2012

Experimental setup
The experimental plots were setup to investigate
the impacts of nitrogen and potassium fertilization on
soil biochemistry and employed a randomized complete
block design with three replicate plots for the fifteen
treatments and unfertilized control plots. The fifteen
treatments included different levels of nitrogen and
potassium (150, 300 and 450 kg ha-1
y -1
) individually and
in various combinations.
Fertilizers were broadcasted in four split doses in
order to avoid volatilization and leaching. Nitrogen was
applied as 25% sulphate of ammonia (containing 20%
nitrogen) and urea (containing 46% nitrogen). Potassium
was applied as muriate of potash (containing 63%
potassium). Sulphate of ammonia was broadcasted at the
rate of 7.5, 15 and 22.5 kg ha-1
between February and
November. Urea at the rate of 17.25, 34.5 and
51.75 kg ha-1
was broadcasted between May and August.
Muriate of potash was applied at the rate of 23.63, 47.25
and 70.88 kg ha-1
along with sulphate of ammonia or
urea. Other nutrients (Phosphorus, Calcium, Magnesium,
Sulphur, Zinc, Manganese and Boron) were applied at
recommended rates and regular cultural practices were
carried out uniformly in all the plots (Verma and Palani,
1997).
Sampling
Soil samples were collected during premonsoon
(March) and monsoon (June) in 2011. Ten soil cores
(5 cm in diameter) at the depths of 0-10 cm (L1 layer)
and 10-20 cm (L2 layer) were randomly taken from each
plot and bulked. Field moist samples were passed
through a 2-mm sieve and divided into two equal parts.
One part was used for the determination of soil moisture,
pH, electrical conductivity, total nitrogen, exchangeable
potassium and organic carbon. The other part was stored
at 4°C prior to microbiological assays.
Soil analysis
Soil moisture content was determined after
drying at 105°C to a constant weight. Soil pH and
Journal of Research in Agriculture (2012) 1(2): 124-135 126
Treatment
Moisture(%)pHEC(dSm-1
)
S1S2S1S2S1S2
L1L2L1L2L1L2L1L2L1L2L1L2
N0K011.00bc11.67de18.00def19.00de3.76f3.36h4.69b4.33d0.216i0.248h0.388e0.332e
N0K1506.67e-h10.00def19.67b-e21.00bcd3.86d3.65c4.79a4.66a0.277g0.309de0.294h0.304f
N0K3008.00de12.00cd19.00b-f21.67bc3.89c3.55d4.60c4.40c0.182j0.211j0.320g0.243i
N0K4505.67fgh9.67efg20.33bc21.00bcd4.32a3.82b4.59c4.47b0.178j0.320d0.239i0.214k
N150K010.00cd11.33de20.33bc22.67b3.55h3.43f4.25d4.38c0.324e0.249h0.335f0.256h
N150K15013.00ab14.00bc20.00bcd21.67bc3.68g3.47e4.26d4.30d0.328e0.225i0.338f0.228j
N150K30011.00bc15.67ab21.00b23.00ab3.43k3.39g4.23de4.33d0.360c0.223i0.346f0.257h
N150K45014.67a16.33a24.00a25.00a3.82e3.43f4.19f4.31d0.365c0.264g0.421d0.367d
N300K07.00efg10.00def18.67c-f19.67cde3.54h3.28i4.20ef4.25e0.245h0.269g0.287h0.299f
N300K1508.00de12.00cd17.67ef19.00de3.50i3.28i4.14g4.32d0.389b0.316de0.345f0.326e
N300K3005.00gh7.00hi18.33c-f18.00e3.46j3.22j3.86k4.40c0.280g0.352b0.491a0.249hi
N300K4504.67h6.00i19.00b-f19.33de4.06b3.97a4.07h4.31d0.304f0.308e0.337f0.420b
N450K07.00efg7.67ghi17.67ef20.00cde3.24m3.03k4.04h4.14g0.454a0.432a0.319g0.325e
N450K1507.00efg9.67efg18.00def18.00e3.43k3.36h3.98i4.20f0.214i0.266g0.343f0.288g
N450K3007.67ef9.00fgh19.33b-e19.67cde3.29l3.21j3.89j4.23ef0.343d0.339c0.473b0.382c
N450K4507.33ef9.00fgh17.00f20.00cde3.29l3.23j4.05h4.23ef0.380b0.287f0.452c0.501a
Table1Physicalcharactersofsoilfor0-10cmlayer(L1)and10-20cmlayer(L2)duringpremonsoon(S1)andmonsoon(S2)seasonsasinfluencedby
nitrogenandpotassiumfertilization.
Meansinacolumnforasoillayerfollowedbysameletter(s)donotsignificantlydiffer(P<0.05)accordingtoDuncan’sMultipleRangeTest.

electrical conductivity were measured using a digital pH
meter (Cyberscan 510, Singapore) and Conductivity
Bridge Meter (ORLAB 201, India). Total nitrogen was
measured using an autoanalyser (Skalar autoanalyser,
Netherlands) after Kjeldahl digestion and distillation.
Exchangeable potassium was extracted in ammonium
acetate solution (pH 7) and measured using a flame
photometer (GENWAY). Total organic carbon was
determined according to Nelson and Sommers (1982).
The titration method of Jaggi (1976) was used to
assess soil respiration. Urease activity was determined
according to Kandeler and Gerber (1988) with urea (1M)
as a substrate and the values were expressed as
µg N.g -1
dm.2h -1
using the calibration curve. Cellulase
activity was determined by incubation of soil samples
with water-soluble carboxymethylcellulose (Schinner
and Von Mersi, 1990) for 24 h at 50°C, pH 5.5. Low
molecular products and sugars resulting from the
enzymatic degradation of carboxymethylcellulose were
used for the quantitative reduction of potassium
hexacyanoferrate II to potassium hexacyanoferrate III,
which reacts with Fe (III) ammonium sulfate to form a
complex known as “Prussian Blue“, which is determined
photometrically at 690 nm. Cellulase activity is
expressed as µg GE g-1
dm 24 h -1
.
Statistical analysis
All data were subjected to analysis of variance
(ANOVA) (IRRISTAT, version 3/93) and Duncan’s
Multiple Range Test (P<0.05) was used to separate the
means when the differences were significant. Pearson’s
correlation analysis was used to assess the relationship
between soil and microbial variables. The latter analysis
was carried out in SPSS 9.0.
RESULTS
Soil properties
Soil in the experimental plots were clayey loam
and fertilizer application had a profound influence on
soil moisture. As expected, soil moisture was
Treatment
Totalnitrogen(%)Exchangeablepotassium(mgkg-1
l)Organiccarbon(%)
S1S2S1S2S1S2
L1L2L1L2L1L2L1L2L1L2L1L2
N0K00.37hi0.29ef0.27fg0.24b155.21h101.83i162.65i107.43k4.83h3.26h3.99h3.55f
N0K1500.36i0.31de0.29efg0.14e248.45d186.88e228.20d197.43d5.24f3.69e4.06h3.63e
N0K3000.40def0.34abc0.24h0.19c259.83c223.59c217.85e157.78e5.07g3.39g4.37g3.00j
N0K4500.38fgh0.27g0.27g0.19c323.70b246.72b281.22b259.77b4.79h3.82d4.91e4.10c
N150K00.38ghi0.28fg0.28fg0.16de136.95j93.35j123.02m115.33i5.00g3.32g4.45g3.08i
N150K1500.47a0.31de0.29ef0.15e141.50i80.88l137.43k115.33i6.07a3.84d3.90i3.20h
N150K3000.38ghi0.28fg0.27g0.31a159.83g119.18g197.20f143.36f5.34e3.33gh5.27c3.39g
N150K4500.42bcd0.27fg0.38b0.30a442.71a313.23a370.01a265.10a5.04g3.80d5.85b3.86d
N300K00.42cde0.33bcd0.37b0.25b76.80n60.86n67.28p88.53m5.46d4.00c4.00h4.02c
N300K1500.42cd0.29efg0.36bc0.31a106.12l80.88l92.90o106.25l5.50cd3.78d5.19c4.96a
N300K3000.39fg0.35a0.36bc0.24b128.02k114.79h152.95j119.92h5.69b4.37a5.93b3.71e
N300K4500.43bc0.31de0.31de0.25b217.02f202.44d192.39g138.61g5.27ef3.59f4.64f3.28h
N450K00.44b0.35ab0.38ab0.16de80.88m73.80m101.76n55.10o5.46d3.94c5.03d3.82d
N450K1500.43bc0.32cd0.35c0.16de128.02k85.00k129.20l75.65n6.01a4.10b4.37g3.28h
N450K3000.40efg0.33abc0.33d0.24b128.02k80.88l187.37h110.77j5.56c4.29a5.19c4.33b
N450K4500.44bc0.34abc0.40a0.17cd223.59e180.88f270.01c201.76c6.08a4.35a6.08a4.29b
Meansinacolumnforasoillayerfollowedbysameletter(s)donotsignificantlydiffer(P<0.05)accordingtoDuncan’sMultipleRangeTest.
Table2Chemicalcharactersofsoilfor0-10cmlayer(L1)and10-20cmlayer(L2)duringpremonsoon(S1)andmonsoon(S2)seasonsasinfluencedbynitrogenand
potassiumfertilization.

significantly higher during monsoon and was affected by
fertilization. Similarly, the L2 layer was moister than the
L1 layer during both the seasons. For premonsoon period,
it ranged between 4.67-14.67% (L1) and 6.00-16.33%
(L2), respectively. On the other hand, it registered
17.00-24.00% (L1) and 18.00-25.00 % (L2) of mixture
for monsoon seasons (Table 1). Soil moisture was higher
in unfertilized soils during both seasons, but
progressively decreased with fertilizer application rates,
especially nitrogen (300 and 450 kg ha-1
).
A significant difference in soil pH was evident
between layers, seasons and most treatments. Soils
fertilized with potassium had higher pH values, the
exception being the 0-10 cm soils fertilized with 300 and
450 kg ha-1
of potassium. In contrast, soils fertilized with
nitrogen had the lowest pH values, and this drop in pH
was more evident in the top 0-10 cm soils than in 10-20
cm soils. Soil pH correlated positively with soil moisture
levels (r = 0.737; P<0.01) (Table 1, 3). Like pH, soil
electrical conductivity also exhibited significant
differences between treatments, seasons and layers.
During premonsoon, soils fertilized with nitrogen had
either almost similar or significantly higher electrical
conductivity values. In contrast during monsoon, soil in
nitrogen fertilized plots had decreased electrical
conductivity values compared to unfertilized plots
(Table 1).
Total soil nitrogen and exchangeable potassium
significantly differed between seasons, layers and among
treatments (Tables 2 and 3). The percentage nitrogen
content of the tea soil was higher during premonsoon
period (S1) when compared to the monsoon season (S2).
Similarly, the nitrogen content of L1 layer was higher
when compared to their respective L2 layer. Further the
application of nitrogen fertilizer at different doses
enhanced the available nitrogen in L1 layer
concomitantly (Table 2). The exchangeable potassium
level was comparable between premonsoon (S1) and
monsoon (S2) seasons and it fluctuated between different
SourceofvariationdfMoisture(%)pHEC(dSm-1
)
Soilnutrients
Totalnitrogen(%)Exchangeable
potassium(mgkg-1
l)
Organiccarbon(%)
Treatment(T)15,12834.25**1549.14**74.64**49.53**1299822839.47**23.06**
Layer(L)1,128100.92**583.84**928.33**3078.56**1627574891.37**156.62**
Season(S)1,1283306.72**84721.78**1598.55**2385.60**911800.35**64.56**
TxL15,1281.39228.48**175.49**28.54**40106426.78**11.13**
TxS15,1287.16**379.04**275.21**37.60**50173100.71**21.50**
LxS1,1288.33**3351.83**266.86**2.052953962.16**140.98**
TxLxS5,1281.2474.64**196.65**29.49**14858168.87**16.02**
Table3F-Valuesofvarioussoilphysicochemicalcharactersasinfluencedbynitrogenandpotassiumfertilization.
**and***significantatP<0.01andP<0.001respectively.

treatment plots in the range of 55.1 and 442.7 mg/ kg dry
soil. However, the potassium content was comparably
higher in the L1 layer than the L2 layer. The application
of increasing doses of muriate of potash in the different
experimental plots resulted in the enhanced amount of
potassium content in both L1 and L2 layers (Table 2).
Generally nitrogen content in the 0-10 cm soils was
higher when compared to their respective 10-20 cm soils.
Exchangeable potassium was lower in nitrogen fertilized
soils than unfertilized soils. Soil nitrogen was
significantly (P<0.01) and negatively correlated to soil
moisture (r = -0.627) and pH (r = -0.518). In contrast,
soil potassium and pH had a significant and positive
correlation (r = 0.267; P<0.05). Organic carbon was
higher in the 0-10 cm soils than in 10-20 cm soils and
significantly varied with fertilization and seasons.
Generally, organic carbon was higher during
premonsoon than monsoon season. As organic carbon
was significantly and positively correlated to electrical
conductivity (r = 0.315; P<0.05) and nitrogen (r = 0.752;
P< 0.01), it was significantly and negatively correlated to
soil moisture (r = -0.334; P<0.01) (Table 3)
Soil respiration
Soil respiration tended to be higher in 0-10 cm
soils and significantly varied between seasons and
among treatments (Fig 1). During premonsoon,
maximum respiration rates were occurred in the 0-10 cm
soils and it was moderate (300 kg ha-1
) and high
(450 kg ha-1
) in potassium fertilized soils. In contrast,
maximum respiration rates in the 10-20 cm soils during
mgCO2.g-1
dm.24
Fig. 1 Influence of nitrogen and potassium fertilization on soil respiration in the two soil layers (L1, L2)
during premonsoon (S1) and monsoon (S2) seasons. Points bearing same letter(s) for a season do not
significantly differ (P<0.05) according to Duncan’s Multiple Range Test
L1
L2
Treatments (Fertilizer dose in kg/ha/y)

premonsoon occurred in soils fertilized with high
nitrogen (450 kg ha-1
). During monsoon, maximum
respiration rates were occurred in the 0-10 cm soils of
treatment involving moderate potassium and high
nitrogen levels (K300 and N450). The respiration rates in
10-20 cm soils during monsoon in fertilized plots were
generally lower compared to unfertilized soils. Soil
respiration was significantly and positively correlated to
soil nitrogen (r=0.325; P<0.001) and potassium
(r =0.309; P<0.05).
Enzyme activities
Application of nitrogen and potassium either
individually or in combinations significantly affected soil
urease activity (Fig 2). Urease activity exhibited different
trends in the two soil layers at different seasons. High
urease activity occurred during premonsoon in 0-10 cm
soils and during monsoon in the 10-20 cm soils.
However, maximum urease activity occurred in soils
fertilized with higher doses of nitrogen and potassium
(N450 and K450) during both the seasons and layers except
in 0-10 cm soils where maximum urease activity was
detected in soils fertilized with low nitrogen and
moderate potassium (N150 and K300). Soil urease activity
was significantly and positively correlated to organic
carbon (r=0.265; P<0.05) and negatively to soil
respiration (r =-0.347; P< 0.01).
Fig. 2 Influence of nitrogen and potassium fertilization on soil urease activity in the two soil layers (L1, L2)
μgN.g-1
dm.2h-1
L1
n p
L1
L2

Cellulase activity in the soil differed
significantly among treatments and between seasons and
soil layers (Fig 3). Cellulase activity was higher in 0-10
cm soils during premonsoon season. There was a greater
cellulase activity in both soil layers during both the
seasons at low nitrogen application rates (N150).
However, increasing concentration of nitrogen
fertilization affected cellulase activity to a greater extent
in the 0-10 cm soils than in 10-20 cm soils. A significant
(P<0.05) positive correlation existed between soil
cellulase activity and total soil nitrogen (r = 0.283).
DISCUSSION
Regular nitrogen fertilization of the acid
soil further acidified the soils. The acidification was
more in sulphate of ammonia application during
premonsoon, than in urea application during monsoon.
These are in accordance with the fact that regular
nitrogen fertilization tend to acidify soils (Khonje et al.,
1989; Darusman et al., 1991). Biederbeck et al., (1996)
indicated that application of anhydrous ammonia
lowered soil pH more than urea, which clearly indicates
varied levels of soil acidification by different nitrogen
sources. Furthermore, soil total nitrogen levels were
lower in plots during urea application than sulphate of
μgGE.g-1
dm.24h-1
Fig. 3 Influence of nitrogen and potassium fertilization on soil cellulase activity in the two soil layers (L1, L2)
L1
L2

ammonia. Most of the broadcasted urea might have
leached out in heavy monsoon showers, as considerable
loss (10-25%) of nitrogen has been reported to occur due
to leaching or volatilization, if urea was not incorporated
into soil soon after its application (Yang, 1991; Byrnes
and Freney, 1995).
The physico-chemical complexity of soil
contributes significantly to underlying variability in
K+
levels with soil pH, moisture and chemical
composition, all having marked effects (e.g. Maathuis
and Sanders, 1996). In particular, acidic pH leads to
desorption of K+
from anionic binding sites in the soil,
and accounts for the tendency towards higher K+
levels
in acidic soils (Gassmann et al., 1993). The
exchangeable potassium increased with increasing
potassium application rates. It has been thought for a
long time that exchangeable potassium do not built up in
the tea soils of south India, because of the dominance of
Kaolinite clay mineral (Verma, 1997; Venkatesan et al.,
2003). However the presence of other minerals other
than Kaolinitic might contribute to the build up of
potassium in the soil (Venkatesan et al., 2004). In this
study, exchangeable potassium was not related to pH,
moisture or chemical composition of the soil. However,
application of nitrogen significantly reduced soil
potassium which ranged from 18-55% in the 0-10cm
soils and 0-38% in 10-20 cm soils. Application of
nitrogen is known to enhance the growth of tea plants.
An increased plant growth resulting from nitrogen
fertilization tends to increase potassium uptake from the
soil. Studies by The Chinese Tea Research Institute
showed that tea leaves contain 1.2-2.5% potassium (TRI,
1997). So a large amount of potassium is being mined
from the soil system by the tea plants as a result of
increased growth response to nitrogen fertilization
(Tchienkoua and Zech, 2004).
The existence of a significant positive correlation
between soil organic carbon and soil nitrogen indicates
an increasing soil organic carbon content with increasing
nitrogen application rates. This is in accordance with
Venkatesan et al., (2004) who has also reported higher
organic carbon in soils fertilized with nitrogen. Further,
Venkatesan et al., (2004), indicated that natural organic
carbon reserves of tea soil would be lost due to no or
inadequate supply of nitrogen because tea plants tended
to mineralize and absorb nutrients from organic matter in
the soil under nutrient stress conditions. In addition,
other studies indicate an increase in soil organic carbon
with increasing soil acidity (Willett et al., 2004; Kemmitt
et al., 2006). Results from this study tended to indicate
that soil pH and organic carbon were negatively
correlated to each other; but this relation is not
statistically significant. However, when the correlation
analysis was staggered between layers, a significant
negative correlation existed between soil pH and organic
carbon in 0-10 cm soils (r = -0.667; P<0.000), but not in
10-20 cm soils (r = -0.193; P>0.05). This varied relation
between soil organic carbon and pH between layers
could be attributed to soil nitrogen which tended to
strongly influence soil pH than soil potassium.
Correlation coefficient values for soil pH and nitrogen in
0-10 cm soils were higher (r= -0.773) compared to
10-20 cm soils (r = -0.734). These observations are in
line with results of Mc Andrew and Malhi (1992) who
reported an increase in soil organic matter with
increasing soil nitrogen.
Soil respiration rates were within normal ranges
reported for natural soils (Srivastava and Singh, 1991;
Maxwell and Coleman, 1995). Results from this study
tended to show that nitrogen and potassium fertilization
affected soil respiration in 0-10 cm soils more than in the
10-20 cm soils. Results of Chen et al., (2002), also
indicate that nitrogen fertilization reduced soil
respiration in 0-10 cm soils. The low respiration rate
with fertilizer application might be attributable to lower
availability of carbon with decreasing soil pH induced by
the nitrogen application (Thirukkumaran and Parkinson,
2000).

Soil urease activity has been reported to follow
changes in soil factors (Cookson and Lepiece, 1996). In
the present study, fertilizer application generally
increased soil urease activity. This is in agreement with
Venkatesan and Senthurpandian (2006), who also
reported an increased urease activity in fertilized tea
soils. However these observations contrasts the studies of
Dick et al., (1988) and Bandick and Dick (1999) where
soil urease activity was reported to decrease with
increasing application of ammonia based nitrogen
fertilizers. Since urease is a substrate inducible enzyme,
the application of fertilizers especially urea could have
resulted in higher urease activity. Further, the binding of
the urease to organic matter insulating itself from
denaturation and biological degradation by soil humic
polymers (Beri et al., 1978; Baligar and Wright, 1991)
could also attribute to increased level of urease as this
urease could be released from these protected sites by
acid sensitive ammonia oxidizers in response to
fertilization (Martikainen, 1985).
Cellulase activity was higher in the surface layer
(0-10 cm soils) than in the subsoils (10-20 cm soils) and
was positively correlated to soil organic matter.
Fertilization increased soil cellulase activity, which are
in accordance with studies of Aescht and Foissner
(1992).
CONCLUSION
Results from the present study revealed that long
term application of nitrogen and potassium fertilizers
affected soil nutrients and pH. Further these fertilizers
can interact with soil microbial communities in a variety
of ways and consequently disturb their normal
functioning. The use of nitrogenous fertilizers is
inevitable and an essential part of agricultural practices.
In the present study, we determined that long–term
application of higher doses of urea or ammonium
sulphate fertilizers had an inverse effect on pH, moisture,
soil respiration and enzyme activities. Therefore the
maintenance of low rates of nitrogen and potassium
(i.e., < 300 kg-1
ha-1
y-1
) are vital for preserving the soil
quality, as higher doses of nitrogen and potassium
(i.e., > 300 kg-1
ha-1
y-1
), adversely affects the soil quality.
However, the actual mechanisms behind these changes
are difficult to infer and needs further investigation.
ACKNOWLEDGEMENTS
I express my sincere thanks to
Dr. N. Muraleedharan, Director, UPASI Tea Research
Institute, Valparai, Coimbatore District, Tamil Nadu,
India for kind permission to use their experimental plots,
which formed vital foundation for this work. I
acknowledge the invaluable help and support rendered
by Dr. S. Premkumar Samuel Asir, Dr. U.I. Baby and
Dr. S. Venkatesan, Dr. R. Selvasundaram, UPASI Tea
Research Institute, Valparai, Coimbatore District, Tamil
Nadu, India during the course of this study.
REFERENCES
Aescht E and Foissner W. 1992. Effects of mineral and
organic fertilizers on the micro fauna in a high-altitude
reafforestation trial. Biology and Fertility of Soils
13:17-24.
Baligar VC and Wright RJ. 1991. Enzyme activities in
Appalachian soils: I. Aryl-sulfatase. Communications in
Soil Science and Plant Analysis 22:305-314.
Bandick AK and Dick RP. 1999. Field management
effects on soil enzyme activities. Soil Biology and
Biochemistry 31:1471-1479.
Beri V, Goswami KP, Brar SS. 1978. Urease activity
and its Michaelis constant for soil systems. Plant and
Soil 49:105-115.
Biederbeck VO, Campbell CA, Ukrainetz H, Curtin
D, Bouman OT. 1996. Soil microbial and biochemical
properties after ten years of fertilization with urea and
anhydrous ammonia. Canadian Journal of Soil Science

76: 7-14.
Byrnes BH and Freney JR. 1995. Recent developments
on the use of urease inhibitors in the tropics. Fertilizer
Research 42:251-259.
Chen CR, Xu ZH, Hughes JM. 2002. Effects of
nitrogen fertilization on soil nitrogen pools and microbial
properties in a hoop pine (Araucaria cunninghamii)
plantation in southeast Queensland, Australia. Biology
and Fertility of Soils 36:276-283.
Cookson P and Lepiece AG. 1996. Urease enzyme
activities in soils of the Batinah region of the Sultanate
of Oman. Journal of Arid Environment 32:225-238.
Darusman, Stone LR, Whitney DA, Janssen KA,
Long JH. 1991. Soil properties after twenty years of
fertilization with different nitrogen sources. Soil Science
Society of America Journal 55:1097-1100.
Dick RP. 1994. Soil enzyme activities as indicators of
soil quality. In: Doran JW, Coleman DC, Bezdicek DF,
Stewart BA. (Eds.), Defining soil quality for a
sustainable environment. Special publication no.35.
SSSA, Madison,WI, 107-124.
Dick RP, Rasmussen PE, Kerle EA. 1988. Influence of
long-term residue management on soil enzyme activities
in relation to soil chemical properties of a wheat-fallow
system. Biology and Fertility of Soils 6:159-164.
Gassmann W, Ward JM, Schroeder JI. 1993.
Physiological roles of inward rectifying K+
channels.
Plant Cell 5:1491-1493.
Jaggi W. 1976. Die Bestimmung der CO2 - Bildung als
Mass der bodenbiologischen Aktivitat. Schw Landw
Forsch 15:371-380.
Kandeler E and Gerber H. 1988. Short – term assay of
soil urease activity using colorimetric determination of
ammonium. Biology and Fertility of Soils 6:68-72.
Kemmitt SJ, Wright D, Goulding KWT, Jones DL.
2006. pH regulation of carbon and nitrogen dynamics in
two agricultural soils. Soil Biology and Biochemistry
38:898-911.
Khonje DJ, Varsa EC, Klubek B. 1989. The
acidulation effects of nitrogenous fertilizers on selected
chemical and microbiological properties of soil.
Communications in Soil Science and Plant Analysis
20:1377-1395.
Maathuis FJM and Sanders D. 1996. Mechanism of
Potassium absorption by higher plant roots. Physiology
Plantarum 96:158-168.
Martikainen PJ. 1985. Nitrification in forest soil of
different pH as affected by urea, ammonium sulphate and
potassium sulphate. Soil Biology and Biochemistry
17:363-367.
Maxwell RA and Coleman DC. 1995. Seasonal
dynamics of nematode and microbial biomass in soils of
riparian-zone forests of the southern Appalachians. Soil
Biology and Biochemistry 27:79-84.
Mc Andrew DW and Malhi SS. 1992. Long-term N
fertilization of a Solonetzic soil: Effects on chemical and
biological properties. Soil Biology and Biochemistry
24:619-623.
Nelson DW and Sommers LE. 1982. Total carbon,
organic carbon and organic matter. In: Page AL, Miller
RH, Keeney DR. (Eds.), Methods of soil analysis. Part -
2. Chemical and microbiological properties. ASA
monograph number 9, Madison,WI, 539-579.
Nioh I, Isobe T, Osada M. 1993. Microbial biomass and
some biochemical characteristics of a strongly acid tea
field soil. Soil Science and Plant Nutrition 39:617-625.
Schinner F and Von Mersi W. 1990. Xylanase-, CM-
cellulase- and invertase activity in soil, an improved

method. Soil Biology and Biochemistry 22:511-515.
Srivastava SC, Singh JS. 1991. Microbial C, N and P in
dry tropical forest soils: effects of alternative land-uses
and nutrient flux. Soil Biology and Biochemistry 23:117-
124.
Tchienkoua M and Zech W. 2004. Organic carbon and
plant nutrient dynamics under three land uses in the
highlands of West Cameroon. Agriculture, Ecosystem
and Environment 104:673-679.
Thirukkumaran CM and Parkinson D. 2000.
Microbial respiration, biomass, metabolic quotient and
litter decomposition in a lodgepole pine forest floor
amended with nitrogen and phosphorous fertilizers. Soil
Biology and Biochemistry 32:59-66.
TRI 1997. Potassium and Magnesium for better tea
production. TRI-IPI.
Venkatesan S, Ganapathy MNK. 2004. Impact of
nitrogen and potassium fertilizer application on quality
of CTC teas. Food Chemistry 84:325-328.
Venkatesan S, Murugesan S, Ganapathy MNK,
Verma DP. 2004. Long–term impact of nitrogen and
potassium fertilizers on yield, soil nutrients and
biochemical parameters of tea. Journal of the Science of
Food and Agriculture 84:1939-1944.
Venkatesan S, Murugesan S, Senthur Pandian VK,
Ganapathy MNK. 2005. Impact of sources and doses of
potassium on biochemical and green leaf parameters of
tea. Food Chemistry 90:535-539.
Venkatesan S, Senthurpandian VK. 2006. Comparison
of enzyme activity with depth under tea plantations and
forested sites in south India. Geoderma 137:212-216.
Venkatesan S, Verma DP, Navaneetha Krishna
Ganapathy M. 2003. Targeted yield equations of
nitrogen for clonal teas under south Indian conditions.
Journal of the Indian Society of Soil Science
51:178- 183.
Verma DP. 1993. Nutrient Management of Tea in South
India. In: Tea Culture Processing and Marketing, Mulky
MJ and Sharma VS (Eds.). Oxford and IBH Publishing
Co. Pvt. Ltd., New Delhi, India, 55-69.
Verma DP. 1997. Potassium nutrition of tea. Journal of
Potassium Research 13:93-100.
Verma DP, Palani N, Balasubramaniam K,
Kumaraguru R, Venkatesan S and Ganapathy MNK.
2001. Nutritional management of tea for sustainable
productivity in South India. The Planters Chronicle,
215-227.
Verma DP and Palani N. 1997. Manuring of tea in
south India (revised recommendations).In: Hand Book of
Tea Culture, (section 11), Valparai, Tamil Nadu, India:
UPASI Tea Research Institute, 33.
Willett VB, Reynolds BA, Stevens PA, Ormerod SJ,
Jones DL. 2004. Dissolved organic nitrogen regulation
in freshwaters. Journal of Environmental Quality
33:201-209.
Yang ZM. 1991. Situation and improving measures of
N fertilizer use efficiency in tea fields of red soil in
China. China Tea 3:10-12.
Submit your articles online at www.jagri.info
Advantages
Easy online submission
Complete Peer review
Affordable Charges
Quick processing
Extensive indexing
You retain your copyright
submit@jagri.info
www.jagri.info/Sumit.php.

Influence of Long Term Nitrogen and Potassium Fertilization on the Biochemistry of Tea Soil

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Influence of Long Term Nitrogen and Potassium Fertilization on the Biochemistry of Tea Soil

Similar to Influence of Long Term Nitrogen and Potassium Fertilization on the Biochemistry of Tea Soil (20)

More from researchagriculture

More from researchagriculture (20)

Recently uploaded

Recently uploaded (20)

Influence of Long Term Nitrogen and Potassium Fertilization on the Biochemistry of Tea Soil