Introduction
Peanut (Arachis hypogaea L.) also known as the
king of oilseed belongs to the family fabaceae as one of the worlds largest
legume crop, ranks 2nd after soybean (Glycine max L.) (Shad et al. 2009) and can be cultivated
across diverse climatic conditions (Kiniry et al. 2005). It is ranked 13th
among the food crops and 4th among oilseed crop, and its haulm
is used as animal feed (El-Akhal et al. 2013; Meena et al. 2016).
The low agricultural productivity of peanut is
attributed to various factors including low quality of seed, imbalanced
fertilizer use, drought, unavailability of irrigation water, seasonal variation
in rainfall patterns, and infertile soils due to low organic matter (Ashfaq et
al. 2003; Hussainy and Arivukodi 2019). As compared to other field crops,
the cultivation of oil seed crops such as soybean, sunflower (Helianthus annuus L.), and peanut have
not received much attention (Kephe et al. 2020). The oil contents of
peanuts are higher than soybean, hence considering peanuts oil quality, its
cultivation could be considered as an alternative (Wang et al. 2012).
Increase in area under cultivation and yield of peanut is possible through
quality seed, proper soil management practices and efficient nutrient
management such as integrated use of organic and inorganic nutrients (Mahrous et al. 2015).
Among the amendments, organic manures improve soil fertility, water-holding capacity,
and overall biomass of plant growth promoting microbes (Esmaeilian et al. 2012). Moreover, organic manures
are being preferred over inorganic fertilizers in improving soil physical
properties (Busscher et al. 2010). Peanut as a
potential oilseed crop requires an adequate amount of nutrients especially
phosphorus (P) and potassium (K). Proper nutrient management is the key factor
among the best agronomic practices, supporting sustainable crop production for
longer run without disturbing soil fertility and health (Sarkar et al.
2017; Kumar et al. 2018). There is a direct relation between the crop
productivity and fertilizer usage. Approximately 50% of the increased
productivity is attributed to the fertilizer use in the last decades (Erisman et
al. 2008). Mostly farmers prefer mineral fertilizers over the organic
manures to increase crop productivity without considering the soil and
environmental health (Abdelhafez et al.
2012). The long-term use of mineral fertilizers can deteriorate soil health
resulting in soil acidification,
poor soil aggregation, and micronutrients deficiency (Karmakar et al. 2020).
It is a fact that the
minimal use of chemical fertilizers and increased use of organic amendments can
positively affect the physico-chemical properties of soil, by influencing pH,
infiltration rate, and water holding capacity and serving as potential
nutrients sources (Mahmoodabadi et al. 2010; Sawrup 2010; Cesarano et
al. 2017). Due to a number of benefits, the
use of soil organic fertilizers is being widely accepted (Uygur and
Karabatak 2009; Urra et al. 2019). Furthermore, the combined use of
organic and inorganic fertilizers could be an appropriate and efficient
practice for increasing the efficiency of the chemical fertilizer improving the
soil health and productivity (Schoebitz and Vidal 2016). Therefore, the present
study was conducted with the aim to investigate the effect of co-application of
organic and inorganic fertilizers on yield, quality of peanut and physical
properties of soil under rain-fed conditions. We
hypothesized that the integrated use of FYM and GYP under field conditions may
improve the yield, protein, oil contents in peanut as well as moiture contents
and reduce the bulk density of soil.
Materials and Methods
Experimental
setup and treatments
A
field experiment was conducted at Barani Agricultural Research Institute,
Chakwal (32° 56' 0" N, 72° 42' 0" E) to evaluate the effect of
organic and inorganic amendments on soil physical properties, peanuts yield and
quality under rain-fed conditions (average rainfall ≤ 600 mm) during the years 2018
and 2019. Two months prior to sowing, poultry manure (PM) (37.1 t ha-1),
farmyard manure (FYM) (49.4 t ha-1), gypsum (GYP) (2.5 t ha-1),
liquid humic acid (HA) (49.4 L ha-1) and GYP (1.2 t ha-1)
+ FYM (24.7 t ha-1) (in 1:1) were applied in the respective plots
(5 m Χ 5 m) following randomized complete block design (RCBD) replicated
thrice. Peanuts seeds of variety BARI-2011 were sown at the rate of 74 kg ha-1
using drill during last week of April and crop was harvested
in the 1st week of November each year. Plant density was maintained 30 days after
sowing, and all other parameters were recorded after 180 days of sowing.
Recommended doses of nitrogen (N), phosphorus (P) and potassium (K) were
applied at the rate of 20, 80, and 60 kg ha-1 using di-ammonium
phosphate (DAP), single super phosphate (SSP) and sulfate of potash (SOP) prior
to sowing during field preparation.
Physico-chemical properties of soil
Two months prior to sowing during both years, a composite
sample of sieved soil (2 mm) was used to analyze the soil physico-chemical
properties and nutrients (i.e., N, P
and K) (Table 1). The soil texture was determined by hydrometer method
(Bouyoucos 1951). While to determine soil moisture content (%), gravimetric
method was followed (Reynolds 1970). Soil electrical conductivity (EC) was
measured using EC meter (S505141 EC Meter, Sper Scientific, USA) while, pH by
the pH meter (HI8520 pH Meter, Hanna Instruments, Italy). The concentrations of
Ca+2 and Mg+2 in soils were determined using EDTA method
(Estefan et al. 2013). Organic matter
content in the soil was determined following Walkley Black method (Walkley and
Black 1934). While, contents of N, P
and K in the soils were determined via
Kjeldhal apparatus (Bremner 1960), spectrophotometer and
flame photometer (Stanford and English 1949), respectively, following standard protocols.
In order to evaluate the effect of different organic and
inorganic amendments on soil physical properties, bulk density, infiltrations
rate, and moisture percentage of soils were determined after harvesting of crop
each year. To determine soil bulk density, undisturbed soil cores having 5 cm
internal diameter and with 6 cm height were drawn from 015 cm and 1530 cm
using a core sampler. After collection, samples were oven dried at 105°C until
constant weight, and bulk density (Mg m−3) was
calculated by dividing the weight of oven dried soil samples to the volume of
core used (Veihmeyer and Hendrickson 1948). While, ring
infiltrometers of large diameter were used to measure infiltration rate
(Johnson 1963). To assess moisture percentage, the gravimetric method was
followed by weighing fresh and oven dried samples. (Topp and
Ferre 2002).
Nutrient analyses of poultry
and farm yard manure
For nutrient analyses of PM
and FYM, 0.5 g sample of each manure was digested with sulfuric acid (H2SO4)
and hydrogen peroxide (H2O2) following method described
by (Wolf 1982). This digestion mixture was heated till the appearance of clear
solution and N, P and K contents were measured using Kjeldahl,
spectrophotometer and flame photometer, respectively (Table 2).
Table 1: Physicochemical characteristics of soils used in this
study prior to sowing during 2018 and 2019
|
Parameters |
2018 |
2019 |
|
Texture |
Sandy clay loam (sand 51.2% clay 29.8% and silt 19%) |
Sandy clay loam (sand
52% clay 28.5% and silt 19.5%) |
|
Moisture (%) |
8.75 ± 0.85 |
10.7 ± 1.10 |
|
pH |
7.85 ± 0.20 |
7.60 ± 0.27 |
|
ECe
(dSm-1) |
1.85 ± 0.07 |
1.91 ± 0.08 |
|
CEC (cmolc kg-1) |
8.60 ± 1.05 |
11.1 ± 1.70 |
|
Soluble Ca2+
+ Mg2+ (mmolc L-1) |
7.15 ± 0.60 |
7.80 ± 0.65 |
|
Organic matter (%) |
0.50 ± 0.03 |
0.57 ± 0.03 |
|
CaCO3 (%) |
4.60 ± 0.19 |
4.90 ± 0.16 |
|
Total nitrogen (%) |
0.47 ± 0.02 |
0.54 ± 0.01 |
|
Available phosphorus
(mg kg-1) |
4.58 ± 0.10 |
5.66 ± 0.15 |
|
Available potassium (
mg kg-1) |
130 ± 14.9 |
141 ± 15.5 |
|
Bulk density (Mg m-3)
(0-15 cm) |
1.42 ± 0.02 |
1.41 ± 0.02 |
|
Bulk density (Mg m-3)
(15-30 cm) |
1.45 ± 0.03 |
1.43 ± 0.03 |
|
Infiltration rate (mm
h-1) |
19.3 ± 1.75 |
18.7 ± 1.30 |
ECe = Electrical conductivity; CEC = Cation exchange
capacity; CaCO3 = Calcium carbonate
Values
represent means (n=3) ± standard errors
Table 2: Nutrients in poultry and
farm yard manures used during 2018 and 2019
|
Parameters |
2018 |
2019 |
||
|
PM |
FYM |
PM |
FYM |
|
|
Nitrogen (%) |
2.80 ± 0.13 |
0.53 ± 0.06 |
2.75 ± 0.11 |
0.51 ± 0.05 |
|
Phosphorus (%) |
1.40 ± 0.08 |
0.21 ± 0.02 |
1.42 ± 0.09 |
0.23 ± 0.03 |
|
Potassium (%) |
1.60 ± 0.09 |
0.60 ± 0.04 |
1.56 ± 0.08 |
0.65 ± 0.05 |
PM = Poultry manure; FYM
= Farm yard manure
Values
represent means (n=3) ± standard errors
Peanut yield and quality attributes
The plant density was recorded on 30th day of
sowing each year. For number of pods plant-1, 100-grain weight and
pods yield, peanut crop was harvested after 180 d of sowing both in 2018 and
2019. To determine the effect of amendments on quality of peanut, the crude
protein and oil contents were analyzed from the harvested peanut seeds. Peanut
seeds were initially dried to a constant weight at 50°C. After de-shelling,
seeds were crushed and ground to a fine powder. To measure crude protein content,
total N content was determined using a digestion and distillation system
following micro-Kjeldahl method (Sweeney and Rexroad 1987), and then crude
protein content was calculated by multiplying N content by a factor of 6.25
(Jones 1931). While, for the oil content, Soxhlet apparatus (Soxtec 2050, FOSS,
Denmark) was used (Niu et al. 2014).
Statistical
analysis
The analysis of variance was used
to estimate variations from mean (n=3) values by standard errors. Means were
compared at 5% level of significance by applying LSD test using Statistix 8.1 (Snedecor and Cochran 1980).
Results
Effects on yield attributes
The results showed that organic and inorganic amendments
did not reveal great differences in plant density among the applied treatments;
however, the combined application of GYP and FYM significantly improved the
plant density by 18% than control, while, 13% higher plant density was observed
by the individual application of HA as compared to control (Fig. 1a).
The application of organic and inorganic fertilizers had
a positive influence on the number of pods of peanut as compared to control
during both years 2018 and 2019 (Fig. 1b). Approximately, 9.6, 29, 17 and 9.8%
more number of pods per plant were observed with application of PM, FYM, GYP,
and HA, respectively than control treatment (Fig. 1b). The combined application
of GYP and FYM had 57% higher number of pods than control.
Application of PM, FYM, GYP, and HA had 16, 17, 13 and
14% higher 100-grain weight, than control treatment respectively (Fig. 1c). The
combined use of GYP and FYM increased 25% 100-grain weight as compared to
control treatment (Fig. 1c). For pods yield, 37, 42, 27 and 17% higher yield
values of peanut were observed on applying PM, FYM, GYP, and HA, than control
respectively (Fig. 1d). While on combined application of GYP and FYM, there was
an increase of 67% in peanut yield than control. Briefly, the application of
organic and inorganic fertilizers had significantly (P ≤ 0.05) improved the yield of peanut as compared to control.
Effects on quality attributes
The co-application of organic and inorganic fertilizers
significantly (P ≤ 0.05)
affected the crude protein and oil content of peanut as compared to control
during both years (Fig. 2a and b).
Results showed that 13, 7.8, 6.7 and 12% higher crude protein contents were
observed with PM, FYM, GYP, and HA, than control respectively (Fig. 2a). The
combined application of GYP and FYM had 22% higher crude protein content than
control. Similarly, 3.6, 2.7, 2.4 and 4.5% higher oil contents were observed on
applying PM, FYM, GYP, and HA, than control respectively (Fig. 2b). Using GYP
in combination with FYM had 8.5% higher oil contents than control.
Effects on
soil properties
%20224-230_files/image002.png)
Fig. 1: Effects of organic and
inorganic amendments on plants density (a),
no. of pods per plant (b),
100-grains weight (c) and pods yield
(d) of peanut grown during 2018 and
2019. Plant density was noticed after 30 d of sowing, and all other values
shown here were taken after 180 d of sowing. Columns and bars represent means
and standard errors, respectively of triplicate values. Means having different
letters differ significantly according to LSD test at P ≤ 0.05. (Control, treatment without any amendments; PM,
treatment with only poultry manure; FYM, treatment with only farm yard manure; GYP, treatment with only
gypsum; GYP + FYM, treatment with both gypsum and farm yard
manure; HA, treatment with only liquid humic acid)
%20224-230_files/image004.png)
Fig. 2: Effect of organic and inorganic amendments on crude
protein contents (a) and oil
contents (b) of peanut grown during
2018 and 2019. All the values shown here were taken after 180 d of sowing.
Columns and bars represent means and standard errors, respectively of
triplicate values. Means having different letters differ significantly
according to LSD test at P ≤
0.05
Co-application of organic and
inorganic fertilizers improved soil physical properties including soil bulk
density, infiltration rate and moisture percentage (Table 3).
Approximately 4.7, 4.8, 3.8 and 4.3% reduced bulk density (0‒15 cm) than control was observed
by the application of PM, FYM, GYP, and HA, respectively (Table 3). While, 8.7%
reduced bulk density was observed on combined application of GYP and FYM.
Almost similar trend was observed for the bulk density of the subsoil (15‒30 cm). On the other hand, 8.9, 8.3, 7.9 and 1.9% reduced
rate of water infiltration was observed on applying PM, FYM, GYP and HA, as
compared to control respectively (Table 3). While on integrated use of GYP and
FYM, 10% decreased water infiltration rate was observed as compared to control.
In case of moisture content, 55, 48, 43 and 17% increased moisture content as compared
to control was observed by the application of PM, FYM, GYP, and HA,
respectively (Table 3), while combined application of GYP and FYM, increased
88% moisture content as compared to control was observed. Briefly, addition of
each organic or inorganic amendment improved the soil physical properties but
the effect of co-application of GYP and FYM was most significant.
%20224-230_files/image005.png)
Discussion
In this study, improved plant density and yield
attributes of peanut were observed on the addition of organic and inorganic
amendments. Taufiq et al. (2016) found improved growth, plants density
and yield of peanut on application of GYP and manures. Kausar et al.
(2020) reported a significant increase in wheat (Triticum aestivum L.)
yield by the addition of GYP and green manures. Improved yield and growth
traits in maize (Zea mays L.) by the
addition of PM and HA might be due to the addition of organic matter by these
amendments, thus improving the physical, chemical, and biological properties of
soil, and increasing nutrients availability within the rhizosphere zone, which
consequently enhanced overall growth and yield attributes of peanut (Rizk et
al. 2012; Zhao et al. 2016; Hussain et al. 2018). Other
possible explanations for the improved yield on applying amendments could be
the enhanced soil moisture retention, which is directly linked with nutrients
mobility and availability as found in present study with increased moisture
percentage and nutrient content found in treatment where GYP and FYM applied in
combination (Parihar et al. 2019; Mariotte et al. 2020).
The improved crude protein and
oil contents in mustard (Brassica juncea L.)
by the application of HA and manure were previously reported by Dubey et al.
(2019). The improved effect on quality of peanut could be due to the increased
nutrients uptake particularly of N, and better translocation of assimilates
(Ravikumar et al. 2019). Combined application of GYP and FYM proved most
effective in improving crude protein and oil contents significantly, and this
promoting effect can be attributed to the ability of FYM and especially GYP to
add sulfur (S) within the soil and as sulfur have major role in synthesis of
protein and oil in oilseed plants (Caires et al. 2006; Rocha et al.
2017; Raza et al. 2018; Ariraman and Kalaichelvi 2020; Chahal et al. 2020).
The integrated use of different organic and inorganic
amendments could significantly improve soil properties (Ahmad et al.
2013). In our study, reduced soil bulk density, water infiltration rate and
improved moisture contents on application of organic and inorganic amendments
were observed. This promotive effect could be due to the fact that organic
amendments together with inorganic fertilizers improve organic matter contents,
soil aggregation, roots growth and consequently increase the total volume of
biopores in the amended plots (Bandyopadhyay et al. 2010; Singh and
Benbi 2016; Bekele et al. 2020) in addition to providing essential
nutrients to increase the soil fertility and productivity (Rasoulzadeh and
Yaghoubi 2010; Agbede et al. 2017). Reduced bulk density on addition of
amendments could be due to the increase in overall volume of pore spaces due to
organic matter addition (He et al. 2020), while the binding/water
holding characteristic of the amendments could be the reason of the reduced
infiltration rate and increased moisture content (Hudson 1994; Verheijen et
al. 2010; Aytenew and Bore 2020).
Conclusion
All the tested organic and inorganic amendments in our
field trial showed improved effects on yield, quality of peanut and soil
physical properties. While, co-application of GYP and FYM was found to the most
effective in improving yield attributes (100 grain weight, no. of pods per
plant and pods yield), quality attributes (crude protein and oil content) of
peanut, and soil physical properties (bulk density, infiltration rate and
moisture percentage). Furthermore, our findings suggest that co-application of
GYP and FYM under rain-fed conditions could serve as a better alternate to the
excessive usage of single source chemical fertilizers in order to achieve the
ultimate goals of sustainable food production having improved yield, quality
and soil physical health.
Acknowledgements
Authors are thankful to the staff of Barani Agricultural
Research Institute (BARI), Chakwal, Pakistan for their support in
providing space in the form of field plots for the experiment and the
laboratory technicians of Soil and Water Testing Laboratory Chakwal, Pakistan
for their assistance in samples analyses.
Author Contributions
RL and ME conceptualized the
study, conducted the experiment, managed the resources and analyzed the data,
MJA, MIK and MSK conducted the statistical analysis, MJA, MIK and MSK wrote
original draft of the manuscript, RL supervised the study and all processes. MAB
visualized the experiment conceptually, SH contributed in editing the
manuscript. MIK corresponded to the journal for submission and review. All
authors have read and agreed to the submitted version of the manuscript.
Conflict of
Interest
Authors declare no conflict of interest.
Data Availability
We hereby declare that data related to this article, are
available with the corresponding author and will be produced on demand.
Ethics Approval
Ethical approval is not applicable in this study.
Funding Source
This study was partially funded by the Higher Education
Commission (HEC) of Pakistan (project number NRPU-7730).
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