Soil Nutrient Availability and Enzyme Activities under Wheat-Green gram Crop Rotation as Affected by Rock Phosphate Enriched Compost and Inorganic Fertilizers

Journal of the Indian Society of Soil Science, Vol. 62, No. 3, pp 224-234 (2014)
Soil Nutrient Availability and Enzyme Activities under Wheat-Green
gram Crop Rotation as Affected by Rock Phosphate Enriched
Compost and Inorganic Fertilizers
P.C. Moharana, D.R. Biswas*, A.K. Patra1
, S.C. Datta,
R.D. Singh, Lata2
and K.K. Bandyopadhyay3
Division of Soil Science and Agricultural Chemistry, Indian Agricultural Research Institute,
New Delhi, 110012
The aim of this study was to evaluate the effect of rock phosphate (RP) enriched rice straw compost, FYM
and inorganic fertilizers on changes in nutrient availability and enzyme activities in soil during different
physiological growth stages under a wheat-green gram crop rotation in an Inceptisol. The matured RP
enriched compost contained higher bioavailable P as well as total P content compared to farmyard manure.
Data revealed that application of inorganic fertilizers and RP enriched compost or FYM either alone or in
combination resulted in significant build-up in soil organic carbon, mineral N, Olsen-P and NH4OAc-K as
well as enzyme activities compared to unfertilized control plots during different physiological growth stages
of wheat and green gram. Plot receiving 50% NPK+RP enriched compost resulted in 100.8, 95.2 and 100.0
per cent greater build-up in Olsen-P over unfertilized control in crown root initiation (CRI), flowering and
maturity stage of wheat, respectively. Irrespective of treatments, build-up of mineral N, Olsen-P and NH4OAc-
K decreased in all the growth stages of green gram as compared to values obtained in wheat. The
dehydrogenase and phosphatase activities (alkaline and acid) were higher in flowering stage than maturity
and CRI stages of wheat. While, higher enzyme activities were obtained during pod formation in green
gram. The results demonstrated that enriched compost could be prepared using low-grade RP with rice straw
and used as an alternate nutrient source for improving crop yields, maintaining soil nutrient availability and
enzyme activities.
Key words: Residue recycling, rock phosphate, enriched compost, nutrient availability, enzyme activities
*Corresponding author: (Email: drb_ssac@yahoo.com)
Present addresses
1
Indian Institute of Soil Science, Nabibagh, Berasia Road,
Bhopal, Madhya Pradesh
2
Division of Microbiology, Indian Agricultural Research Insti-
tute, New Delhi, 110012
3
Division of Agricultural Physics, Indian Agricultural Research
Institute, New Delhi, 110012
Management and recycling of farm wastes of diverse
organic sources into quality compost is becoming very
popular these days. Preparation and use of mineral
enriched compost has become an important compo-
nent of sustainable cropping systems and received
much interest in recent years as a means of increasing
soil organic matter and serves as the potential source
of nutrients for plant growth. It is estimated that ap-
proximately 550 million tonnes (Mt) of crop residues
are produced in India per year. The major share is the
rice residues which are usually burnt in the fields,
particularly in northern parts of Indo-Gangetic Plains
of India to save labour as well as to enable tillage and
seeding machinery to work efficiently and to sow the
next crop of wheat without loss of time. As a result,
substantial amounts of potent organic matter and nu-
trients are lost besides polluting the environment
(Yadvinder-Singh et al. 2005). The alternative means
to utilize crop residues and recycle them back to the
agricultural field is by composting technology, which
is recognized as an economical and sustainable op-
tion for management of agricultural waste and can be
followed at the local site of the produce, thus reduce
the ill effects of residue burning (Biswas 2011). In
recent years, interest in composting has also increased
because of the social demand for an environmental
friendly waste treatment technology and advent of or-
ganic farming. It is the most acceptable methods of
recycling of organic matter and agriculture residues
(Gaind et al. 2009; Antil and Raj 2012; Sharma et al.
2014).

2014] NUTRIENT AVAILABILITY AND ENZYME ACTIVITIES UNDER WHEAT-GREEN GRAM 225
Cost of water soluble phosphatic fertilizers has
increased tremendously in India in recent times be-
cause of importing raw materials like high-grade rock
phosphate (RP) and sulphur, imposing heavy burden
on government exchequer. A substantial amount of
RP is available in India, but most of them are low-
grade and unsuitable for manufacturing of commer-
cial P-fertilizers as well as for direct use as a source
of P to crops, particularly in neutral and alkaline soils
(Narayanasamy and Biswas 1998). An alternative
means of improving the availability of P from RP
could be incorporating them into composting mass,
wherein the organic acids produced during the de-
composition of fresh organic matter help in the solu-
bilization of P from RP into plant available form
(Biswas and Narayanasamy 2006; Biswas et al. 2009).
Soil enzymes regulate the transformation of nu-
trients in soil required for plant growth (Saha et al.
2008). Transformation of organic P through enzymatic
reactions and immobilization of P in the biomass play
an important role in P cycling and are likely to be
affected by P amendments. However, there is limited
information available on the effect of enriched com-
post prepared using crop residues and low-grade RP
in soils under field conditions in intensive cropping
sequence on changes in soil available nutrients and
enzymes activities during crop growth stages in a
wheat-green gram crop rotation. The present study
was therefore aimed to prepare and assess the impact
of rock phosphate enriched compost and chemical fer-
tilizers on soil nutrient availability and enzyme activi-
ties during different physiological growth stages un-
der wheat-green gram crop rotation in an Inceptisol
of Indo-Gangetic Plains of India.
Materials and Methods
Mass Production and Analysis of Enriched Compost
Mass production of RP enriched rice straw com-
post was done at the Biomass Utilization Unit of IARI
as per the procedure outlined earlier by Biswas and
Narayanasamy (2006). For this, RP was obtained from
Rajasthan State Mines and Minerals Ltd., Udaipur,
Rajasthan. The powdered RP (100-mesh particle size)
had 8.81% total P, 0.002% water soluble P (WSP),
1.29% citrate soluble P (CSP), 6.5% Ca, 5.6% Mg,
0.10% Fe, and 665, 21.7 and 41.7 mg kg-1
of Mn, Cu
and Zn, respectively. Rice straw was collected from
the Research Farm of IARI, New Delhi. It contained
total carbon (C) 49.8%, total N 0.53%, C/N ratio 93.9,
total P 0.04%, total K 1.07%, and Fe, Mn, Cu and Zn
content of 262, 33, 12 and 49 mg kg-1
, respectively.
The composting was done layer-wise, where rice straw
was spread on the floor of an area approximately 20
m × 2 m. A layer of RP (2% P, w/w) was spread over
rice straw. Then a layer of fresh cattle dung was
spread over the composting mass as natural inocu-
lants for faster decomposition. Water was added so as
to maintain the moisture content about 50-60%
throughout the composting period. Mechanical turn-
ings were employed at 30, 60 and 90 days of
composting to provide adequate aeration, thorough
mixing of composting mass and uniform decomposi-
tion.
Fresh samples of matured compost (120-days-
old) were drawn from three different locations and
divided into two portions. The first portion was kept
in a refrigerator at 4 o
C and used subsequently for
analysis of total N, mineral N (NH4
+
-N + NO3
-
-N) and
enzyme activities like dehydrogenase, acid
phosphatase and alkaline phosphatase; whereas the
other portion was oven-dried at 65±1 °C for 24 h,
ground to pass through a 2-mm sieve, and analyzed
for pH, EC, total C, N, P and K as well as Olsen-P,
WSP, CSP and NH4OAc-K as per the standard
procedures. The pH and EC were measured using
compost: water ratio of 1:5. Total C content was
determined by the ignition method. Total N content
was determined by the micro-Kjeldahl method
(Bremner and Mulvaney 1982). For determination of
total P and K, the di-acid digestion (HNO3:HClO4::
9:4) method was followed. Total P content was
determined by a spectrophotometer after developing
vanadomolybdo-phosphoric yellow colour complex,
while total K was determined by a flame photometer.
Mineral N (NH4
+
-N + NO3
-
-N) was determined by the
method as outlined by Keeney and Nelson (1982).
Olsen-P was determined using 0.5 M NaHCO3 (pH
8.5) extract (Olsen et al. 1954), while available K
was determined using 1 N NH4OAc (pH 7.0) (Hanway
and Heidel 1952). Dehydrogenase activity was
measured as per the method of Klein et al. (1971)
while, phosphates activity was measured as per the
procedure outlined by Tabatabai and Bremner (1969).
Water soluble carbon (WSC) was analyzed by
extracting sample with water followed by estimation
of carbon by wet digestion method (Walkley and
Black 1934). Bio-available P consisting of WSP and
CSP was determined as per the procedure outlined by
Fertiliser (Control) Order (FCO 1985). Similar
procedures were followed for characterization of
farmyard manure (FYM) and RP enriched compost.
Experimental Details and Soil Analyses
This experiment was conducted from November
2011 to November 2012 under a wheat-green gram

226 JOURNAL OF THE INDIAN SOCIETY OF SOIL SCIENCE [Vol. 62
cropping system at the Research Farm, Indian Agri-
cultural Research Institute, New Delhi. Representa-
tive composite sample from surface soil (0–15 cm
depth) was collected from the experimental field for
initial soil properties. The soil belongs to Inceptisol,
member of coarse loamy, non-acid, mixed hyperther-
mic family of Typic Haplustept. Some of the physico-
chemical properties of the experimental soil were: tex-
ture sandy loam with sand 67.2%, silt 14.8% and clay
18.0%; pH 8.1, EC 0.35 dS m-1
, CEC 10.5 cmol(p+
)kg-1
soil, organic C 3.2 g kg-1
, mineral-N 21.2 mg kg-1
,
Olsen-P 12.4 kg ha-1
and NH4OAc-K 145 kg ha-1
.
The field experiment was carried out to assess
the impact of the RP enriched compost and FYM with
and without chemical fertilizers on soil nutrient avail-
ability and enzyme activities in a wheat-green gram
crop rotation. Six nutrient management practices con-
sisted of T1: control, T2:100% recommended dose of
fertilizer (100% NPK), T3: FYM @ 5.0 t ha-1
(FYM),
T4: RP enriched compost @ 5.0 t ha-1
(RP enriched
compost), T5: 50% NPK+ FYM @ 5.0 t ha-1
(50%
NPK+FYM) and T6: 50% NPK+ RP enriched com-
post @ 5.0 t ha-1
(50% NPK+RP enriched compost)
were followed. The experiment was laid out in a ran-
domized block design having plot size of 3.5 m × 4 m
each with three replications. Wheat (Triticum
aestivum) var. HD-2851 was grown as the first crop
and green gram (Vigna radiata) was grown as the
second crop to evaluate the direct and residual effects
of different nutrient management practices. The rec-
ommended doses of nitrogen (120 kg N ha-1
), phos-
phorus (60 kg P2O5 ha-1
) and potassium (60 kg K2O
ha-1
) as well as other treatments were computed as per
the treatment combinations. Urea and diammonium
phosphate (DAP) were used as the source of N, while
DAP and muriate of potash (MOP) were used as the
source of P and K, respectively. Whole quantities of
enriched compost, FYM and NPK fertilizers were ap-
plied at the last ploughing and mixed thoroughly into
the soil.
Soil samples were collected from each plot at
three physiological growth stages of wheat (crown
root initiation, CRI; flowering and maturity) and green
gram (flowering, pod formation and maturity) and ana-
lyzed for organic C (Walkley and Black 1934), min-
eral N (Keeney and Nelson 1982), Olsen-P (Olsen et
al. 1954), NH4OAc-K (Hanway and Heidel 1952) as
well as enzyme activities like dehydrogenase activity
(Klein et al. 1971), acid and alkaline phosphatase ac-
tivities (Tabatabai and Bremner 1969).
Statistical Analysis
The data were analysed for comparing means
employing analysis of variance and computing criti-
cal difference of different nutrient management dur-
ing different physiological growth stages on soil nu-
trient availability and enzyme activities using SPSS
window version 16.0 (SPSS Inc., Chicago, USA).
Duncan multiple range test (DMRT) was performed
to see the difference between the treatments.
Results and Discussion
Quality of RP Enriched Compost vis-à-vis FYM
The quality of the matured RP enriched rice
straw compost vis-à-vis FYM in terms of their chemi-
cal composition and enzyme activities are presented
in table 1. It is evident that total C content in RP
Table 1. Characteristics of rock phosphate enriched compost and FYM (mean ± standard deviation)
Quality parameters RP enriched compost FYM
pH 7.74 ± 0.10 7.47 ± 0.17
Electrical conductivity (EC, dS m-1
) 3.72 ± 0.08 2.45 ± 0.13
Total organic C (TOC, %) 22.8 ± 0.90 34.6 ± 1.2
Water soluble C (WSC, %) 0.11 ± 0.04 0.02 ± 0.003
Total N (%) 1.51 ± 0.06 1.39 ± 0.03
C/N ratio 15.1 ± 0.35 24.9 ± 0.48
NH4
+
-N (mg kg-1
) 423 ± 31 393 ± 28
NO3
-
-N (mg kg-1
) 611 ± 60 549 ± 27
Total P (%) 2.42 ± 0.03 0.46 ± 0.06
Olsen-P (g kg-1
) 1.12 ± 0.07 0.65 ± 0.12
Water soluble P (WSP, %) 0.11 ± 0.003 0.36 ± 0.04
Citrate soluble P (CSP, %) 1.54 ± 0.06 0.08 ± 0.01
Total K (%) 1.29 ± 0.02 1.11 ± 0.02
NH4OAc-K (%) 0.55 ± 0.12 0.50 ± 0.05
Dehydrogenase activity (µg TPF h-1
g-1
compost) 85.5 ± 6.5 82.3 ± 7.4
Alkaline phosphatase (µg PNP h-1
g-1
compost) 1530 ± 25 997 ± 15
Acid phosphatase (µg PNP h-1
g-1
compost) 723 ± 3 405 ± 23

enriched compost decreased substantially to 22.8%
compared to the initial total C in rice straw (49.8%).
On the other hand, total N content was increased to
1.51% in RP enriched compost compared to initial
total N content in rice straw (0.53% N). The total C
and N content in FYM used in this study for compari-
son was 34.6 and 1.39%, respectively. The loss of
total C in the matured RP enriched compost is attrib-
uted to the oxidation of organic matter (total C) as
CO2 and generation of heat during composting pro-
cess. The increase in total N in enriched compost over
the initial value of N in raw rice straw may be due to
the net loss of total C as CO2 and water by evapora-
tion during composting. This might also be due to
mineralization of N with the progress of composting
period. The results are in agreement with the work
done by Biswas and Narayanasamy (2006) and Biswas
et al. (2009).
The C/N ratio in enriched compost markedly de-
creased (15.1) compared to the raw rice straw which
had a C/N ratio of 93.9. In case of FYM, the C/N
ratio was 24.9. It is reported that the C/N ratio is one
of the main characteristics that describe the maturity
of compost. It gives an indication of N availability for
the process of biological degradation, and the decrease
in this ratio with composting time has been widely
reported as an indicator of maturity for composting
processes (Biswas et al. 2009). The narrowing of C/N
ratio with the progress of composting is because of
decomposition of organic matter wherein the C con-
tent of the compostable mixtures decreased with time
due to loss of carbon as CO2 in respiration, while N
content per unit material increased, which resulted in
the decrease of the C/N ratio. Similar results in de-
crease in total C and increase in total N content per
unit of material during the decomposition of different
organic wastes were reported by other workers
(Nishanth and Biswas 2008).
Farmyard manure had a lower P content (0.46%)
than RP enriched compost (2.42% P). The increase in
total P is attributed to contribution of P from RP in
enriched compost. The result confirms the findings of
earlier work of Biswas and Narayanasamy (2006).
However, it was observed that enriched compost had
lesser amounts of WSP content than FYM; while a
substantial improvement in CSP content was noticed
in enriched compost compared to FYM, indicating
that RP enriched compost had greater amounts of bio-
available P (WSP+CSP) than FYM. The carbonic acid
and organic acids produced during the decomposition
of organic matter solubilize apatite in the RP, result-
ing in the release of phosphate and calcium into the
solution (Biswas et al. 2009). Enriched compost also
had greater amounts of dehydrogenase, acid and alka-
line phosphatase activities compared to FYM, indi-
cating the better quality of enriched compost produced
using rice straw mixed with RP.
Changes in Soil Fertility
Soil organic carbon
It is evident that the soil organic carbon (SOC)
content increased significantly due to various nutrient
management practices in all the physiological growth
stages of wheat as compared to unfertilized control
plot (Table 2). The SOC content improved signifi-
cantly in plots receiving application of enriched com-
post and FYM alone as well as in combination with
50% NPK as compared to 100% NPK (T2) in all
growth stages of wheat. At CRI stage, SOC content
increased by 46.2 per cent with 100% NPK treated
plot over unfertilized control plot (3.7 g kg-1
). Fur-
ther, these values increased by 85.5 and 69.8 per cent
with combined application of 50% NPK+FYM (T5)
and 50% NPK+RP enriched compost (T6), respec-
tively. Similar trend in improvement in SOC contents
due to different nutrient management were also ob-
served at flowering and maturity stages of wheat. It is
evident that with the advancement of physiological
growth stages of wheat, SOC status decreased from
CRI stage to maturity stage irrespective of treatments.
Data also revealed that SOC was significantly influ-
enced by residual effect of various nutrient manage-
ment practices during different physiological growth
stages of green gram (Table 2). Data showed that
SOC varied from 3.4 to 4.9 g kg-1
in flowering; 3.3 to
4.8 g kg-1
in pod formation and 3.1 to 4.4 g kg-1
in
maturity stage of green gram due to different treat-
ments. The plot receiving 50% NPK+FYM resulted
in significantly higher SOC in all the growth stages
of green gram as compared to other treatments except
plot receiving 50% NPK+RP enriched compost. At
flowering stage, SOC increased by 26.1 per cent with
100% NPK treated plot over control, while, these val-
ues increased by 44.2 and 32.1 per cent with com-
bined application of 50% NPK+FYM and 50%
NPK+RP enriched compost, respectively.
The improvement in enhancing SOC in plot re-
ceiving 50% NPK along with enriched compost may
be attributed to balanced and integrated use of inor-
ganic and organic sources of nutrients. This may be
attributed to enhanced crop growth which in turn, re-
sulted in increased below-ground organic residues
(e.g., root biomass, rhizodeposition, root exudates
etc.), and thus raised the SOM status. The increased
SOM in enriched compost amended plots also may be
attributed to slower break down rate (less and con-

stant mineralization rate) of enriched compost in soil.
Kundu et al. (2007) reported that soil organic C con-
tent improved in fertilized plots as compared to the
unfertilized plots due to C addition through the roots
and crop residues, higher humification rate constant,
and lower decay rate. Similarly, in a long-term ex-
periment, Moharana et al. (2012) observed that the
SOC was considerably greater in soils receiving FYM
along with NPK fertilizer than in plots receiving
merely NPK fertilizer. In this study, the combination
of organic and inorganic fertilization enhanced the
accumulation of SOC, which is consistent with other
studies (Majumdar et al. 2008; Banger et al. 2009).
Mineral N
Mineral N (NH4
+
-N + NO3
-
-N) in soil increased
significantly due to application of RP enriched com-
post and FYM with and without inorganic fertilizers
during different physiological growth stages of wheat
than unfertilized control (Table 3). Among the nutri-
ent management practices, significantly higher amount
of mineral N in soils were observed in 100% NPK
treated plots in all the growth stages of wheat. It was
observed that plot receiving 100% NPK increased
mineral N by 93.3, 130.3 and 112.6 per cent over
control in CRI, flowering and maturity stages, respec-
tively. While, treatment receiving enriched compost
maintained significantly lower mineral N at CRI stage,
but registered higher build-up in mineral N at the lat-
ter stages, particularly at maturity. Further, it was ob-
served that combined application of 50% NPK+RP
enriched compost registered mineral N which was at
par with 100% NPK treated plot, but out yielded
higher mineral N in all the growth stages of wheat
than sole application of enriched compost or FYM.
Data revealed that significantly higher amounts of
mineral N in soils were observed in treatments receiv-
ing 50% NPK +RP enriched compost which resulted
in 91.4, 142.0 and 119.7 per cent greater build-up in
mineral N over unfertilized control in flowering, pod
formation and maturity stages of green gram, respec-
tively (Table 3). Sole application of FYM or RP en-
riched compost resulted in significantly lower mineral
N in all the physiological growth stages of green gram.
In general, build-up of mineral N decreased in all the
growth stages in green gram grown on residual fertil-
Table 2. Changes in soil organic C content during different physiological growth stages of wheat and green gram grown in
sequence as affected by application of RP enriched compost
Treatment Soil organic C (g kg-1
) content under
Wheat (direct effect) Green gram (residual effect)
CRI Flowering Maturity Flowering Pod formation Maturity
T1: Control 3.7d 3.6d 3.5c 3.4c 3.3c 3.1b
T2: 100% NPK 5.4c (46.2)# 4.7c (30.3) 4.3b (24.2) 4.3b (26.1) 4.3ab (27.1) 3.7b (14.0)
T3: FYM 6.2b (67.4) 5.7ab (56.8) 4.7b (33.8) 4.5ab (31.9) 4.3a (29.7) 4.0ab (22.9)
T4: RP enriched compost 5.7bc (55.7) 5.5bc (50.7) 4.6b (31.4) 4.3ab (26.5) 4.1b (21.8) 3.8b (15.2)
T5: 50% NPK+FYM 6.8a (85.5) 6.4a (76.3) 5.6a (61.5) 4.9ab (44.2) 4.8a (43.9) 4.8a (45.5)
T6: 50% NPK+RP enriched compost 6.3ab (69.8) 6.2a (72.6) 5.4a (53.9) 4.5a (32.1) 4.4ab (31.5) 4.2ab (28.6)
# Figure in parentheses indicate per cent increase over control
* For each parameter, different lower case letter within the same column indicate that the treatments are significantly different at
P<0.05 according to DMRT for separation of means
Table 3. Changes in mineral-N in soil during different physiological growth stages of wheat and green gram grown in sequence
as affected by application of RP enriched compost
Treatment Mineral N (mg kg-1
) content under
T1: Control 37.7d 47.9e 43.7e 37.8d 33.0d 36.8d
T2: 100% NPK 72.8a (93.3)# 110.3a (130.3) 92.9b (112.6) 58.8bc (55.6) 58.5c (77.0) 64.3b (74.7)
T3: FYM 46.1c (22.4) 72.7d (51.7) 60.3d (37.9) 43.1d (14.0) 50.5c (52.8) 55.5c (50.7)
T4: RP enriched compost 56.8b (50.7) 88.8c (85.4) 76.1c (74.1) 55.1c (45.9) 59.4c (79.7) 64.5b (75.4)
T5: 50% NPK+FYM 59.1b (57.1) 101.0b (110.8) 92.4b (111.4) 64.6b (70.9) 69.2b (109.6) 70.0b (90.2)
T6: 50% NPK+ RP enriched 71.3a (89.3) 112.7a (135.2) 102.1a (133.5) 72.3a (91.4) 79.9a (142.0) 80.8a (119.7)
compost

ity compared to values obtained in wheat (direct ef-
fect) irrespective of treatments. According to Rees
and Castle (2002) application of manures leads to an
enrichment of the soil N pool, and increases the effi-
ciency of organic fertilizer by releasing higher min-
eral N. Organic manures release mineral N slowly,
which help in supplying higher mineral N to crops,
particularly latter stages of crops. A major proportion
of basal dose of fertilizers transforms into mineral N
and utilized by the crop during initial stages of crop
growth because of more requirement of N at the early
stage. These results suggest that integrated nutrient
management was more persistent in supplying min-
eral N in soil than only chemical N fertilizers.
Whereas, application of 100% organic could not main-
tain the level of mineral N in soil than that obtained
under inorganic or integrated sources.
Olsen-P
Application of RP enriched compost and inor-
ganic fertilizers to wheat had an immense impact on
dynamics of P release during different physiological
growth stages of crop because of mineralization of P
from RP enriched compost as evident from the greater
build-up in Olsen-P in soil (Table 4). At CRI stage,
plots receiving 50% NPK+RP enriched compost re-
sulted in significantly higher Olsen -P than other treat-
ments. Greater amounts of Olsen-P in soil were main-
tained due to 50% NPK+RP enriched compost treated
plot in flowering and maturity stages of wheat. It is
evident that treatment receiving 100% NPK recorded
significantly higher Olsen-P at CRI stage than RP en-
riched compost alone because of presence of higher
amount of water soluble P in the former. However,
RP enriched compost registered greater amount of
available P at the latter stages, particularly at maturity
which is comparable to 100% NPK treated plots. It is
also evident that the amounts of Olsen-P in soil de-
clined gradually in 100% NPK treated plot with the
advancement of physiological growth stages of wheat,
while these values were increased gradually due to
50% NPK+RP enriched compost treated plot. This
might be due to the fact that P content in RP enriched
compost, being less soluble, released P slowly and
maintained greater amounts of P in soil at the latter
part of the crop growth than the former which is more
water soluble form and subjected to greater fixation
in soil.
Significant release of available P due to com-
bined use of inorganic fertilizers and enriched com-
post clearly indicates the beneficial effect of integrated
nutrient management in enhancing available P in soils
during different growth stages of wheat. It is also
evident that enriched compost had a considerable re-
sidual effect on subsequent crop as evident from
greater build-up on Olsen-P in soils. This may be at-
tributed to increased availability of P (citrate soluble
and organic P) in RP enriched compost than FYM
(Biswas and Narayanasamy 2006). The released phos-
phate was then immobilized into the microbial cells
as evidenced by higher water soluble, citrate soluble
and organic P contents in the final product. Increase
in available P content during growth stages of wheat
may be attributed to the microbial P present in RP
enriched compost which acts as a slow release fertil-
izer due to its slow rate of decomposition and pro-
vides available P to plants for a longer period instead
of fixation and/or precipitation in soil minerals as in
case of commercial water soluble P-fertilizer (Verma
et al. 2013). This might be due to the fact that the
major P fraction added through RP enriched compost
is in the organic pool, which mineralized slowly with
time (Biswas and Narayanasamy 2006). That is why
increase in available P content in soil with P addi-
Table 4. Changes in Olsen-P in soil during different physiological growth stages of wheat and green gram grown in sequence as
affected by application of RP enriched compost
Treatment Olsen-P (kg ha-1
) in soil under
T1: Control 12.1e 12.6c 13.0d 12.1d 11.6d 11.1c
T2: 100% NPK 21.3ab (76.5)# 21.5ab (70.1) 19.9c (53.5) 17.1c (41.4) 16.0bc (37.9) 15.0b (35.3)
T3: FYM 15.7d (29.6) 17.1b (35.2) 18.6c (43.7) 15.8c (30.8) 15.7c (34.9) 15.6b (41.0)
T4: RP enriched compost 18.2cd (50.4) 19.2b (52.0) 20.8bc (60.5) 19.9b (64.9) 19.0b (63.3) 17.3b (55.7)
T5: 50% NPK+FYM 20.2bc (66.9) 20.9ab (65.7) 22.5b (73.6) 20.3b (68.4) 18.5b (59.4) 17.4b (57.4)
T6: 50% NPK+ RP enriched 24.3a (100.8) 24.6a (95.2) 25.9a (100.0) 23.5a (94.7) 22.6a (94.8) 21.7a (95.6)
compost

tions through inorganic fertilizer and RP enriched
compost is expected with the advance of growth stages
of wheat.
NH4
OAc-K
Significant build-up in NH4OAc-K was observed
due to application of organic and inorganic fertilizers
either alone or in combination in different physiologi-
cal growth stages of wheat over control (Table 5).
Plots receiving 100% NPK maintained significantly
higher NH4OAc-K in all the growth stages of wheat
than others except plots receiving 50% NPK+RP en-
riched compost which was at par. Plots receiving
100% NPK increased NH4OAc-K by 38.2, 44.2 and
42.3 per cent higher over control in CRI, flowering
and maturity stages, respectively. In general, higher
amounts of NH4OAc-K were found in the flowering
stage followed by pod formation and maturity stage
of green gram irrespective of treatments. It was evi-
dent that plot receiving 50% NPK+RP enriched com-
post increased NH4OAc-K by 29.5, 26.5 and 26.7 per
cent higher in flowering, pod formation and maturity
stages of green gram, respectively over control
Dehydrogenase Activity
Data revealed significant variations in dehydro-
genase activity in soils due to different nutrient man-
agement practices under present wheat-green gram ro-
tation (Fig. 1). It was evident that plots receiving
100% NPK increased dehydrogenase activity by 31.7
per cent over control. While, plots receiving FYM
and RP enriched compost resulted an increase in de-
hydrogenase activity by 39.3 and 47.1 per cent over
control, respectively. Dehydrogenase activity in-
creased further due to conjoint use of either FYM or
RP enriched compost with 50% NPK by 53.9 and
69.5 per cent, respectively over control. Irrespective
of treatments, dehydrogenase activities were higher in
the flowering stage than CRI and maturity stages of
wheat. Significantly higher dehydrogenase activity
was maintained due to application of 50% NPK+RP
enriched compost even in all the physiological growth
stages of green gram than other nutrient management
practices (Fig. 1). It improved dehydrogenase activity
by 82.4, 47.0 and 47.1 per cent over control at flow-
ering, pod formation and maturity stages of green
gram, respectively over control.
Dehydrogenase activity is considered an indica-
tor of overall microbial activity because it occurs in-
tra-cellularly in all living microbial cells, and it is
linked with microbial respiratory processes (Bolton et
al. 1985). Therefore, the use of dehydrogenase activ-
ity as an index of microbial activity has been sug-
gested by many workers (Nannipieri et al. 1990). Use
of different nutrient management promoted a signifi-
cant increase in dehydrogenase activity in wheat and
green gram rhizosphere compared to control. In gen-
eral, the peak dehydrogenase activity was observed in
flowering stage and then declined subsequent. The
lower values of dehydrogenase activity after flower-
ing may be explained by the fact that addition of more
stable organic matter may not improve the microbial
activity for a longer duration (Marzadori et al. 1996).
Saha et al. (2008) observed that manure application
increased soil dehydrogenase activity significantly.
The present results suggest that application of FYM
and RP enriched compost directly or indirectly influ-
ences the enzyme activity, which in turn regulates
nutrient transformation. Application of balanced and
integrated use of nutrients improved the organic mat-
ter status of soils, which enhanced dehydrogenase ac-
tivity. It was also observed in the present study that
dehydrogenase activity is less influenced by mineral
N fertilization, which is in agreement with the studies
Table 5. Changes in NH4OAc-K in soil during different physiological growth stages of wheat and green gram grown in
sequence as affected by application of RP enriched compost
Treatment NH4OAc-K (kg ha-1
) in soil under
T1: Control 158d 156d 151c 149d 143e 136e
T2: 100% NPK 219a (38.2)# 225a (44.2) 215a (42.3) 199a (33.5) 191a (33.9) 178a (30.9)
T3: FYM 181c (14.4) 186c (19.0) 178b (17.3) 169c (13.4) 158d (10.7) 155d (14.1)
T4: RP enriched compost 192bc (21.6) 200b (28.3) 190b (25.8) 173c (16.4) 162cd (13.5) 159cd (16.4)
T5: 50% NPK+FYM 196b (23.7) 200b (28.3) 191b (25.9) 182bc (21.9) 169c (18.3) 168bc (23.1)
T6: 50% NPK+ RP enriched 217a (37.3) 219a (40.2) 214a (41.5) 193ab (29.5) 180b (26.5) 173ab (26.7)
compost

of Kautz et al. (2004). The stronger effects of FYM
or RP enriched compost on dehydrogenase activity
might be due to more easily decomposable compo-
nents of organic matter on the metabolism of soil mi-
croorganisms.
Phosphatase activity
Alkaline phosphatase activity increased signifi-
cantly due to application of RP enriched compost and
inorganic fertilizers in different physiological growth
stages of wheat than control (Fig. 2). Among the nu-
trient management practices, significantly higher
amount of alkaline phosphatase activity was observed
in 50% NPK+RP enriched compost treated plots in
all the crop growth stages. It was observed that plot
receiving 100% NPK increased alkaline phosphatase
activity by 13.1, 21.7 and 32.6 per cent over control
in CRI, flowering and maturity stages, respectively.
While, plot receiving RP enriched compost alone in-
creased alkaline phosphatase activity by 36.4, 33.5
and 47.0 per cent in CRI, flowering and maturity
stages, respectively. Further, it was observed that com-
*Error bars represent standard deviation of the mean.
**T1: Control; T2: 100% NPK; T3: FYM; T4: RP enriched compost; T5: 50% NPK+FYM; T6: 50% NPK+RP enriched compost
Fig. 2. Changes in alkaline phosphatase activity in soil as affected by RP enriched compost, FYM and inorganic fertilizer
application during different physiological growth stages of wheat and green gram
* Error bars represent standard deviation of the mean.
Fig. 1. Changes in dehydrogenase activity in soil as affected by RP enriched compost, FYM and inorganic fertilizer application
during different physiological growth stages of wheat and green gram

bined application of 50% NPK+RP enriched compost
resulted in 50.3, 42.9 and 56.9 per cent greater alka-
line phosphatase activity in CRI, flowering and matu-
rity stages, respectively. Significantly higher amounts
of acid phosphatase activity was maintained in plots
receiving 50% NPK+RP enriched compost in all the
growth stages of wheat over plots receiving 100%
NPK as well as RP enriched compost applied alone
(Fig. 3). Plots receiving 50% NPK+RP enriched com-
post resulted in 76.4, 130.6 and 133.9 per cent greater
build-up in acid phosphatase activity over control.
Similar trend on acid phosphatase activity was ob-
served in case of green gram grown on residual fertil-
ity (Fig. 3). Plots receiving 50% NPK+RP enriched
compost resulted in 113.0, 106.2 and 106.1 per cent
greater acid phosphatase activity over control in flow-
ering, pod formation and maturity stages, respectively.
These values for 100% NPK treated plots were 36.1,
38.4 and 24.7 per cent over control in respective
stages.
Phosphatases are inducible enzymes excreted by
plant roots and soil organisms, which can be stimu-
lated by P starvation (Tarafdar and Jungk 1987).
Therefore, phosphatase activities have been regarded
as an important factor in maintaining and controlling
mineralization rate of soil organic P, and a good indi-
cator of P-deficiency (Vance et al. 2003). Mainte-
nance of acid phosphatase activity in unamended con-
trol soil confirms the report that organic manure/com-
post did not alter the enzyme-substrate affinity, while
mineral fertilizer reduced this affinity or changed the
composition and activity of soil microbiota
(Masciandro et al. 2000). The phosphatase activity
increases when the sources of nutrients have an equili-
brated balance between C and N (Nannipieri 1994).
Thus, integrated use of manures and fertilizers had
greater phosphatase activity than 100% NPK as evi-
denced in our present study.
Pearson’s correlation matrix revealed the exist-
ence of significant linear relationship (P<0.01) be-
tween soil nutrient availability and enzyme activity as
influenced by different nutrient management (Table
6). It was observed that SOC was significantly and
positively correlated with mineral N, Olsen-P and
NH4OAc-K in both wheat and green gram. Similarly,
SOC was correlated with all enzymes assayed except
alkaline phosphatase in wheat. Mineral N also showed
positive correlations with Olsen-P, NH4OAc-K, dehy-
drogenase, alkaline phosphatase and acid phosphatase
activity. Strong relationships were noticed between
Olsen-P with NH4OAc-K, dehydrogenase, alkaline
phosphatase and acid phosphatase activity. It was also
revealed that NH4OAc-K maintained positive relation-
ship with dehydrogenase, alkaline phosphatase and
acid phosphatase activity. Further, dehydrogenase ac-
tivity shared a strong correlation with alkaline phos-
phatase and acid phosphatase activity, which are in-
volved in P transformation.
Conclusions
The results demonstrated that application of rock
phosphate enriched compost in combination with 50%
inorganic fertilizer is the most desirable in order to
improve nutrient availability and enzyme activities in
*Error bars represent standard deviation of the mean.
Fig. 3. Changes in acid phosphatase activity in soil as affected by RP enriched compost, FYM and inorganic fertilizer applica-
tion during different physiological growth stages of wheat and green gram

soil. Thus, it can be concluded from the present study
that enriched compost could be prepared using low-
grade rock phosphate and rice straw which could be
used as an alternate nutrient source for maintaining
soil nutrient availability and enzyme activities, thereby
50% costly chemical fertilizers could be saved.
Acknowledgments
The senior author thanks to the Indian Agricul-
tural Research Institute, New Delhi for providing fi-
nancial support as senior research fellowship during
his research work and the Head, Division of Soil Sci-
ence and Agricultural Chemistry, Indian Agricultural
Research Institute, New Delhi for providing facilities
for successful completion of the research works.
References
Antil, R.S. and Raj, D. (2012) Chemical and microbiologi-
cal parameters for the characterization of maturity of
composts made from farm and agro-industrial wastes.
Archives of Agronomy and Soil Science 58, 833-845.
Banger, K., Kukal, S.S., Toor, G., Sudhir, K. and
Hanumanthraju, T.H. (2009) Impact of long-term ad-
ditions of chemical fertilizers and farmyard manure
on carbon and nitrogen sequestration under rice-cow-
pea cropping system in semiarid tropics. Plant and
Soil 318, 27-35.
Biswas, D.R. (2011) Nutrient recycling potential of rock
phosphate and waste mica enriched compost on crop
productivity and changes in soil fertility under po-
tato–soybean cropping sequence in an Inceptisol of
Indo-Gangetic Plains of India. Nutrient Cycling in
Agroecosystems 89, 15-30.
Biswas, D.R. and Narayanasamy, G. (2006) Rock phos-
phate enriched compost: an approach to improve low-
grade Indian rock phosphate. Bioresource Technol-
ogy 97, 2243-2251.
Biswas, D.R., Narayanasamy, G., Datta, S.C., Geeta, S.,
Mamata, B., Maiti, D., Mishra, A. and Basak, B.B.
(2009) Changes in nutrient status during preparation
of enriched organomineral fertilizers using rice straw,
low-grade rock phosphate, waste mica, and phosphate
solubilizing microorganism. Communications in Soil
Science and Plant Analysis 40, 2285-2307.
Bolton, H., Elliott, L.F., Papendick, R.I. and Bezdicek, D.F.
(1985) Soil microbial biomass and selected soil en-
zyme activities: effect of fertilization and cropping
practices. Soil Biology and Biochemistry 17, 297-302.
Bremner, J.M. and Mulvaney, C.S. (1982) Nitrogen-total.
In Methods of Soil Analysis. Part 2: Chemical and
Microbiological Properties (A.L. Page, R.H. Miller,
D.R. Keeney, Eds.), Soil Science Society of America,
Madison, pp. 595-624.
FCO (1985) The Fertiliser (Control) Order, 1985 and The
Essential Commodities Act, 1955. The Fertiliser As-
sociation of India, New Delhi.
Gaind, S., Nain, L. and Patel, V.B. (2008) Quality evalua-
tion of co-composted wheat straw, poultry droppings
and oil seed cakes. Biodegradation 20, 307-317.
Hanway, J.J. and Heidel, H. (1952) Soil analysis methods
as used in Iowa State College Soil Testing Labora-
tory. Iowa Agriculture 57, 1-31.
Table 6. Correlation matrix between available nutrients and soil enzyme activities under a wheat-green gram crop rotation (n =
54, data pooled from all three stages)
Parameter SOC Mineral-N Olsen-P NH4OAc-K Dehydrogenase Alkaline Acid
phosphatase phosphatase
Direct effect (Wheat)
SOC 1.00
Mineral-N 0.321*
1.00
Olsen-P 0.537**
0.744**
1.00
NH4OAc-K 0.515**
0.749**
0.784**
1.00
Dehydrogenase 0.593**
0.777**
0.673**
0.589**
1.00
Alkaline phosphatase 0.240 0.823**
0.602**
0.451**
0.804**
1.00
Acid phosphatase 0.587**
0.860**
0.830**
0.723**
0.869**
0.841**
1.00
Residual effect (Green gram)
SOC 1.00
Mineral-N 0.488**
1.00
Olsen-P 0.568**
0.807**
1.00
NH4OAc-K 0.508**
0.603**
0.631**
1.00
Dehydrogenase 0.654**
0.702**
0.828**
0.583**
1.00
Alkaline phosphatase 0.478**
0.835**
0.713**
0.321*
0.731**
1.00
Acid phosphatase 0.509**
0.848**
0.781**
0.331*
0.764**
0.950**
1.00
**Correlation is significant at the 0.01 level; *Correlation is significant at the 0.05 level

Kautz, T., Wirth, S. and Ellmer, F. (2004) Microbial activ-
ity in a sandy arable soil is governed by the fertiliza-
tion regime. European Journal of Soil Biology 40,
87-94.
Keeney, D.R. and Nelson, D.W. (1982) Nitrogen-inorganic
forms. In Methods of Soil Analysis. Part 2. Chemical
and Microbiological Properties (A.L. Page, R.H.
Miller, D.R. Keeney, Eds.), Second ed. American So-
ciety Agronomy, Madison, pp. 643-698.
Klein, D.A., Loh, T.C. and Goulding, R.L. (1971) A rapid
procedure to evaluate dehydrogenase activity in soil
of low organic matter. Soil Biology and Biochemistry
3, 385-387.
Kundu, S., Bhattacharyya, R., Prakash, V., Gupta, H.S.,
Pathak, H. and Ladha, J.K. (2007) Long-term yield
trend and sustainability of rainfed soybean–wheat sys-
tem through farmyard manure application in a sandy
loam soil of the Indian Himalayas. Biology and Fer-
tility of Soils 43, 271-280.
Majumdar, B., Mandal, B. and Bandyopadhyay, P.K. (2008)
Soil organic carbon pools and productivity in relation
to nutrient management in a 20-year-old rice-berseem
agro-ecosystem. Biology and Fertility of Soils 44,
451-561.
Marzadori, C., Clavatta, C., Montecchio, D. and Gessa, C.
(1996) Effect of lead pollution on different soil enzyme
activities. Biology and Fertility of Soils 22, 53-58.
Masciandro, G., Ceccanti, B., Ronchi, V. and Baner, C.
(2000) Kinetic parameters of dehydrogenase in the
assessment of the response of soil to vermicompost
and inorganic fertilisers. Biology and Fertility of Soils
32, 479-483.
Moharana, P.C., Sharma, B.M., Biswas, D.R., Dwivedi, B.S.
and Singh, R.V. (2012) Long-term effect of nutrient
management on soil fertility and soil organic carbon
pools under a six-year old pearl millet-wheat crop-
ping system in an Inceptisol of subtropical India. Field
Crops Research 136, 32-41.
Nannipieri, P. (1994) The potential use of soil enzymes as
indicators of productivity, sustainability and pollu-
tion. In Soil Biota Management in Sustainable Farm-
ing Systems (C.E. Pankhurst, Ed.), CSIRO, East
Melbourne, Victoria, Australia, pp. 238-244.
Nannipieri, P., Grego, S. and Ceccanti, B. (1990) Ecologi-
cal significance of biological activity. In Soil Bio-
chemistry (J.M. Bollag and G. Stotzky, Eds.), vol. 6.
Marcel Dekker, New York, pp. 293-355.
Narayanasamy, G. and Biswas, D.R. (1998) Phosphate rocks
of India–potentialities and constraints. Fertiliser News
43, 21-32.
Nishanth, D. and Biswas, D.R. (2008) Kinetics of phospho-
rus and potassium release from rock phosphate and
waste mica enriched compost and their effect on yield
and nutrient uptake by wheat (Triticum aestivum).
Bioresource Technology 99, 3342-3353.
Olsen, S.R., Cole, C.V., Watanabe, F.S. and Dean, L.A.
(1954) Estimation of available phosphorus in soils by
extraction with sodium bicarbonate. United States De-
partment of Agriculture Circular No. 939.
Rees, R. and Castle, K. (2002) Nitrogen recovery in soils
amended with organic manures combined with inor-
ganic fertilizers. Agronomie 22, 739-746.
Saha, S., Ved Prakash, Kundu, S., Kumar, N. and Mina,
B.L. (2008) Soil enzymatic activity as affected by
long term application of farm yard manure and min-
eral fertilizer under a rainfed soybean–wheat system
in N-W Himalaya. European Journal of Soil Biology
44, 309-315.
Sharma, A., Sharma, R., Arora, A, Shah, R., Singh, A,
Pranaw, K. and Lata, N. (2014) Insights into rapid
composting of paddy straw augmented with efficient
microorganism consortium. International Journal of
Recycling of Organic Waste in Agriculture 3, 54. DOI
10.1007/s40093-014-0054-2.
Tabatabai, M.A. and Bremner, J.M. (1969) Use of
p-nitrophenyl phosphate for assay of soil phosphatase
activity. Soil Biology and Biochemistry 1, 301-
307.
Tarafdar, J.C. and Jungk, A. (1987) Phosphatase activity in
the rhizosphere and its relation to the depletion of
soil organic phosphorus. Biology and Fertility of Soils
3, 199-204.
Vance, C.P., Uhde-Stone, C. and Allan, D.L. (2003) Phos-
phorus acquisition and use: critical adaptations by
plants for securing a nonrenewable resource. New
Phytologist 157, 423-447.
Verma, S.L., Penfold, C. and Marschner, P. (2013)
Mobilisation of rock phosphate by surface applica-
tion of compost. Biology and Fertility of Soils 49,
287-294.
Walkley, A. and Black, I.A. (1934) An examination of the
Degtjariff method for determining soil organic mat-
ter, and a proposed modification of the chromic acid
titration method. Soil Science 37, 29-38.
Yadvinder-Singh, Bijay-Singh and Timsina, J. (2005) Crop
residue management for nutrient cycling and improv-
ing soil productivity in rice-based cropping systems
in the tropics. Advances in Agronomy 85, 269-407.
Received 29 April 2014; Received in revised form 31 July 2014; Accepted 30 September 2014

Soil Nutrient Availability and Enzyme Activities under Wheat-Green gram Crop Rotation as Affected by Rock Phosphate Enriched Compost and Inorganic Fertilizers

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Viewers also liked

Viewers also liked (7)

Similar to Soil Nutrient Availability and Enzyme Activities under Wheat-Green gram Crop Rotation as Affected by Rock Phosphate Enriched Compost and Inorganic Fertilizers

Similar to Soil Nutrient Availability and Enzyme Activities under Wheat-Green gram Crop Rotation as Affected by Rock Phosphate Enriched Compost and Inorganic Fertilizers (20)

More from Pravash Chandra Moharana

More from Pravash Chandra Moharana (9)

Recently uploaded

Recently uploaded (20)

Soil Nutrient Availability and Enzyme Activities under Wheat-Green gram Crop Rotation as Affected by Rock Phosphate Enriched Compost and Inorganic Fertilizers