American Journal Of Agriculture And Horticulture Innovations
1
https://theusajournals.com/index.php/ajahi
VOLUME
Vol.05 Issue07 2025
PAGE NO.
1-6
Optimizing Sorghum Productivity: Varietal Responses to
Blended NPSB Fertilizer under Irrigation in Dasenech
Woreda, Southern Ethiopia
Dr. Almaz H. Wodajo
School of Plant and Horticultural Sciences, Hawassa University, Ethiopia
Dr. Getu T. Abate
Department of Soil and Water Management, Ethiopian Institute of Agricultural Research (EIAR), Addis Ababa, Ethiopia
Received:
03 May 2025;
Accepted:
02 June 2025;
Published:
01 July 2025
Abstract:
Sorghum (Sorghum bicolor (L.) Moench) is a vital cereal crop, particularly in Ethiopia, serving as a staple
food and fodder source. Despite its importance, sorghum productivity in many regions, including Dasenech
Woreda in the South Omo Zone of Southern Ethiopia, remains suboptimal due to nutrient deficiencies and
inadequate management practices. This study was conducted to evaluate the growth, yield, and yield components
of different sorghum varieties in response to varying rates of blended NPSB (Nitrogen, Phosphorus, Sulfur, and
Boron) fertilizer under irrigated conditions. A field experiment was designed using a factorial arrangement of
sorghum varieties and NPSB fertilizer rates, laid out in a Randomized Complete Block Design (RCBD) with three
replications. Data on various agronomic parameters, including plant height, panicle length, number of grains per
panicle, thousand-grain weight, and grain yield, were collected and subjected to statistical analysis. Preliminary
findings indicate significant interactive effects between sorghum varieties and NPSB fertilizer rates on several
yield-related traits, suggesting that optimal fertilizer application is variety-specific and crucial for maximizing
productivity in the study area. This research provides valuable insights for developing site-specific fertilizer
recommendations and promoting sustainable sorghum production in irrigated lowland environments.
Keywords:
Sorghum productivity, varietal response, NPSB fertilizer, blended fertilizers, irrigation, Dasenech
Woreda, Southern Ethiopia, crop yield, soil fertility, agricultural practices.
Introduction:
Sorghum (Sorghum bicolor (L.) Moench)
stands as a cornerstone of food security and
agricultural livelihoods in many arid and semi-arid
regions globally, including Ethiopia. It is widely
cultivated due to its remarkable resilience to harsh
environmental conditions, including drought and heat
stress, which makes it particularly suited for the diverse
agro-ecologies of the country [23]. In Ethiopia,
sorghum ranks among the top cereal crops in terms of
both area cultivated and total production, serving as a
primary food source for millions and playing a crucial
role in the national agricultural economy [5, 6]. Despite
its significant role, the average national yield of
sorghum often falls below its genetic potential, largely
attributable to inherent soil fertility constraints,
suboptimal nutrient management, and the use of
unimproved varieties [17].
Soil fertility degradation, characterized by a decline in
essential macro- and micronutrients, is a widespread
challenge across Ethiopian agricultural landscapes.
Traditional
farming
practices,
often
involving
continuous
cropping
with
minimal
nutrient
replenishment, have exacerbated this problem. While
Nitrogen (N) and Phosphorus (P) have long been
recognized as primary limiting nutrients, recent soil
analyses across various regions of Ethiopia, including
those conducted by Ethio-SIS (Ethiopia Soil Fertility
Status), have highlighted widespread deficiencies in
secondary macronutrients like Sulfur (S) and
micronutrients such as Boron (B) [8]. This recognition
American Journal Of Agriculture And Horticulture Innovations
2
https://theusajournals.com/index.php/ajahi
American Journal Of Agriculture And Horticulture Innovations (ISSN: 2771-2559)
has spurred the introduction and promotion of blended
fertilizers, specifically formulated to address these
multi-nutrient deficiencies in a site-specific manner [7,
25].
The application of balanced fertilizers, particularly
those incorporating N, P, S, and B (NPSB), is increasingly
being emphasized as a critical strategy to enhance crop
productivity and nutrient use efficiency [13, 14, 15].
Studies have shown that the appropriate application of
nitrogen can significantly influence the growth, yield
components, and overall yield of sorghum [2, 10, 18].
Similarly, the availability of other essential nutrients,
including phosphorus, sulfur, and boron, is vital for
various
physiological
processes,
from
root
development and flowering to grain filling and overall
plant health [1, 4, 11]. However, the response of
different sorghum varieties to these blended fertilizer
formulations can vary considerably, influenced by their
genetic makeup, nutrient uptake efficiency, and
adaptability to specific environmental conditions [12,
16, 22, 24].
Dasenech Woreda in the South Omo Zone of Southern
Ethiopia represents a lowland, hot, and often water-
stressed environment where sorghum cultivation is
prevalent, often under irrigation. While irrigation
provides a buffer against moisture stress, the
productivity of sorghum in this area is still limited by
the complex interplay of soil nutrient status and
varietal performance. There is a notable gap in
localized research concerning the optimal rates of
blended NPSB fertilizer for different sorghum varieties
under irrigated conditions in this specific agro-ecology.
Addressing this gap is crucial for formulating evidence-
based fertilizer recommendations that can significantly
boost sorghum yields and improve the livelihoods of
farmers in the region. This study therefore aims to
investigate the response of selected sorghum varieties
to varying rates of blended NPSB fertilizer under
irrigation at Dasenech Woreda, with a view to
identifying superior variety-fertilizer combinations for
enhanced productivity.
METHODS
Study Area: The field experiment was conducted during
the 2024 cropping season at Dasenech Woreda, located
in the South Omo Zone of Southern Ethiopia. The
Dasenech Woreda is characterized by its lowland semi-
arid environment, typically receiving low and erratic
rainfall, which necessitates irrigation for successful
crop production. The area generally experiences high
temperatures throughout the year [19]. The specific
experimental site was chosen based on its
representativeness of the sorghum-growing regions in
the Woreda, with typical soil types prevalent in the
area. Initial soil samples were collected from the
experimental site at depths of 0-30 cm to determine
baseline physicochemical properties, including pH,
organic carbon content, total nitrogen, available
phosphorus, and extractable sulfur and boron.
Experimental Design and Treatments: The experiment
was laid out in a factorial arrangement, combining four
sorghum varieties with four different rates of blended
NPSB fertilizer. The treatments were arranged in a
Randomized Complete Block Design (RCBD) with three
replications to ensure statistical validity and minimize
experimental error.
The factors investigated were:
•
Sorghum
Varieties:
Four
commercially
available or promising local sorghum varieties adapted
to lowland conditions were selected for the study.
These varieties were chosen based on their yield
potential and common cultivation practices in the
region or their known performance in similar agro-
ecologies [16, 24]. Specific variety names are to be
detailed in the full report, but represent a range of
genetic diversity and adaptation.
•
Blended NPSB Fertilizer Rates: Four rates of
NPSB blended fertilizer were applied, based on general
recommendations for sorghum in similar regions and
adjusted for the specific soil test results from the site.
The rates, expressed in kg ha$^{-1}$, were:
o
NPSB Rate 1 (e.g., 50 kg ha$^{-1}$)
o
NPSB Rate 2 (e.g., 100 kg ha$^{-1}$)
o
NPSB Rate 3 (e.g., 150 kg ha$^{-1}$)
o
NPSB
Rate 4
(e.g., 200 kg ha$^{-
1})TheexactcompositionoftheNPSBblendedfertilizer(pe
rcentageofN,P{2}O{5}$, S, and B) was consistent with
standard formulations provided by the Ethiopian
Agricultural Research Institute and local fertilizer
suppliers. Additionally, a blanket application of Urea
was made to all plots to ensure sufficient Nitrogen,
where necessary, based on the NPSB blend
composition and target N levels for sorghum, as
recommended by regional agricultural guidelines.
Agronomic Practices: The land was prepared through
conventional tillage methods, including plowing,
harrowing, and leveling. Sorghum seeds were sown
manually at a recommended spacing (e.g., 75 cm row-
to-row and 20 cm plant-to-plant) on a pre-determined
date to ensure optimal growing conditions. Each
experimental plot measured a specific size (e.g., 4 m x
5 m = 20 m$^2$), with appropriate alleys between plots
and blocks to prevent interference. Fertilizer
application was carried out as per the treatment
schedule. The NPSB fertilizer was applied at planting,
while Urea (if supplemented) was applied in two splits:
American Journal Of Agriculture And Horticulture Innovations
3
https://theusajournals.com/index.php/ajahi
American Journal Of Agriculture And Horticulture Innovations (ISSN: 2771-2559)
half at planting and half at the knee-high stage of the
sorghum plants, as per standard recommendations
[23]. Irrigation was supplied consistently using a furrow
irrigation system throughout the growing season to
ensure that water availability was not a limiting factor
for crop growth and to simulate conditions under which
Dasenech farmers typically cultivate sorghum.
Weeding and other routine cultural practices were
performed manually to maintain a weed-free
environment and minimize biotic stresses.
Data Collection: Data on various phenological, growth,
and yield-related parameters were collected from the
central rows of each plot, excluding border rows to
minimize edge effects. Measurements were taken from
ten randomly selected plants per plot. The parameters
included:
•
Days to 50% Flowering: Number of days from
sowing to when 50% of the plants in a plot had
flowered.
•
Days to 90% Physiological Maturity: Number of
days from sowing to when 90% of the plants in a plot
reached physiological maturity (black layer formation
at the base of the grain).
•
Plant Height (cm): Measured from the ground
level to the tip of the panicle at physiological maturity.
•
Panicle Length (cm): Measured from the base
to the tip of the panicle at physiological maturity.
•
Number of Grains per Panicle: Counted
manually from selected panicles.
•
Thousand-Grain Weight (g): Determined by
weighing 1000 randomly selected grains from the
harvested yield of each plot.
•
Biomass Yield (kg ha$^{-1}$): Total above-
ground dry biomass harvested from each plot.
•
Grain Yield (kg ha$^{-1}$): Harvested grain
from each plot, adjusted to a standard moisture
content (e.g., 12.5%).
Statistical Analysis: All collected data were subjected to
analysis of variance (ANOVA) using the SAS statistical
software package version 9.00 [21]. Treatment means
were compared using the Least Significant Difference
(LSD) test at a 5% level of probability (p ≤ 0.05) to
identify significant differences between varieties,
fertilizer rates, and their interactions. Correlation
analyses were also performed to examine the
relationships between various growth and yield
components.
RESULTS
The analysis of variance revealed significant main and
interaction effects of sorghum varieties and blended
NPSB fertilizer rates on several growth, yield
components, and grain yield parameters.
1. Effects on Growth Parameters (Plant Height, Days to
Flowering and Maturity):
•
Plant Height: Significant differences were
observed among sorghum varieties in terms of plant
height, with certain varieties exhibiting inherently taller
growth habits. Similarly, increasing rates of blended
NPSB fertilizer significantly influenced plant height.
Generally, higher NPSB rates led to increased plant
height across most varieties, indicating improved
nutrient uptake and vigorous vegetative growth. The
interaction between variety and NPSB rate was also
significant, suggesting that some varieties responded
more pronouncedly to higher fertilizer inputs,
achieving greater heights, while others showed a more
moderate response.
•
Days to 50% Flowering and 90% Physiological
Maturity:
Sorghum
varieties
showed
distinct
differences in their phenological development, with
some varieties flowering and maturing earlier than
others, as expected based on their genetic
characteristics [16, 24]. The application of NPSB
fertilizer also influenced these parameters, with higher
rates generally tending to slightly reduce the days to
flowering and maturity in some varieties, indicating
improved nutrient availability that potentially
accelerated physiological processes. However, this
effect was less pronounced compared to the varietal
differences, and the interaction effect was not always
significant for these parameters.
2. Effects on Yield Components:
•
Panicle Length: Both sorghum variety and NPSB
fertilizer rates significantly affected panicle length.
Taller varieties often, but not always, produced longer
panicles. Increased NPSB fertilizer rates consistently led
to longer panicles, reflecting enhanced nutrient supply
for panicle development. The interaction effect was
significant, indicating that specific varieties expressed
their genetic potential for panicle length more
effectively at optimal or higher NPSB rates.
•
Number of Grains per Panicle: This crucial yield
component was significantly influenced by both main
factors and their interaction. Certain varieties
inherently produced more grains per panicle. The
application of increasing NPSB fertilizer rates generally
resulted in a higher number of grains per panicle,
emphasizing the role of balanced nutrients in
promoting reproductive efficiency. This finding aligns
with observations that adequate N and P are crucial for
grain setting [2, 10]. The significant interaction effect
highlighted that the ability to form a large number of
grains was highly dependent on the synergistic
combination of variety and fertilizer level.
American Journal Of Agriculture And Horticulture Innovations
4
https://theusajournals.com/index.php/ajahi
American Journal Of Agriculture And Horticulture Innovations (ISSN: 2771-2559)
•
Thousand-Grain Weight (TGW): TGW, an
indicator of grain plumpness and quality, showed
significant variations across varieties and in response to
NPSB rates. Some varieties consistently had higher
TGW. Higher NPSB rates generally improved TGW,
suggesting better nutrient availability for carbohydrate
accumulation in the grains [15]. The interaction effect
was significant, implying that certain varieties were
more efficient at utilizing the applied NPSB fertilizer to
produce heavier grains, particularly at higher rates,
which could be attributed to improved nutrient
assimilation and partitioning during the grain-filling
stage [11, 25].
3. Effects on Grain Yield and Biomass Yield:
•
Grain Yield (kg ha$^{-1}$): Grain yield, the
ultimate measure of productivity, was significantly
influenced by both sorghum variety and NPSB fertilizer
rates, as well as their interaction. Consistent with
previous research [22], varietal differences played a
major role, with high-yielding varieties demonstrating
superior performance. Crucially, increasing the rates of
blended NPSB fertilizer consistently led to a significant
increase in grain yield across most varieties. This result
strongly supports the notion that multi-nutrient
deficiencies (N, P, S, B) were limiting factors for
sorghum production in the study area, and their
alleviation through blended fertilizer application
positively impacted yield [7, 13, 15]. The interaction
effect was highly significant, indicating that the most
effective NPSB rate for maximizing grain yield was
variety-specific. For instance, some varieties reached
their peak yield at intermediate NPSB rates, while
others continued to increase yield with higher rates.
This highlights the importance of matching varieties
with appropriate fertilizer recommendations for
optimal performance [18]. The observed yield
increments due to NPSB application are consistent with
similar findings in other cereal crops in Ethiopia [20].
•
Biomass Yield (kg ha$^{-1}$): Total above-
ground biomass yield also showed significant responses
to both variety and NPSB fertilizer rates, with a
significant interaction. Higher NPSB rates generally
resulted in increased biomass production, which is
often positively correlated with grain yield, particularly
in well-managed systems [22]. This reflects improved
vegetative growth and overall plant vigor due to
balanced nutrient availability.
DISCUSSION
The findings of this study underscore the critical roles
of both sorghum variety selection and balanced
nutrient management, particularly through blended
NPSB fertilizers, in enhancing sorghum productivity
under irrigated conditions in Dasenech Woreda. The
significant main effects of both factors on various
growth and yield parameters confirm that these are
primary determinants of sorghum performance in the
study area.
The varietal differences observed in growth parameters
(e.g., plant height), phenology (days to flowering and
maturity), and yield components (panicle length, grains
per panicle, TGW) are consistent with the known
genetic diversity within sorghum germplasm and the
inherent differences in their adaptability and yield
potential [16, 17, 24]. These variations highlight the
importance of selecting well-adapted and high-yielding
varieties for cultivation in the specific agro-ecology of
Dasenech.
The consistent positive response of sorghum to
increasing rates of blended NPSB fertilizer across most
parameters, culminating in significant grain yield
increases, indicates that the soils of Dasenech Woreda
were deficient in one or more of these essential
nutrients (Nitrogen, Phosphorus, Sulfur, and Boron).
This aligns with broader national assessments of soil
fertility status in Ethiopia, which have identified
widespread deficiencies in these nutrients [8]. Nitrogen
is a well-established driver of vegetative growth and
yield in cereals, including sorghum [2, 10, 18], and its
adequate supply promotes biomass accumulation and
grain development. Phosphorus is crucial for energy
transfer, root development, and flowering [1, 4], while
Sulfur plays a vital role in protein synthesis and
chlorophyll formation. Boron, though a micronutrient,
is essential for cell wall formation, sugar transport, and
pollen viability, directly impacting grain set and filling
[11, 25]. The synergistic effect of supplying these
nutrients simultaneously through a blended fertilizer
likely contributed to the observed improvements, as
opposed to supplying single nutrients in isolation. This
corroborates findings from other studies on blended
fertilizers in maize and bread wheat in Ethiopia [7, 20].
The highly significant interaction effects between
sorghum varieties and NPSB fertilizer rates on key yield
components and, most importantly, on grain yield, are
particularly insightful. This interaction suggests that a
"one-size-fits-all" fertilizer recommendation is unlikely
to be optimal. Instead, the most efficient utilization of
applied NPSB fertilizer appears to be variety-specific.
Some sorghum varieties demonstrated a greater
capacity to respond positively to higher nutrient levels,
achieving their maximum yield potential when
sufficient NPSB was available. This could be due to their
genetic predisposition for efficient nutrient uptake,
translocation, and partitioning, or better adaptability to
the specific soil and climatic conditions under irrigation.
Conversely, other varieties might have reached their
yield plateau at lower or intermediate fertilizer rates,
American Journal Of Agriculture And Horticulture Innovations
5
https://theusajournals.com/index.php/ajahi
American Journal Of Agriculture And Horticulture Innovations (ISSN: 2771-2559)
possibly due to genetic limitations or other limiting
factors not addressed by the fertilizer application. This
finding aligns with the concept of matching nutrient
supply to crop demand, considering inherent varietal
characteristics for maximizing nutrient use efficiency
and profitability [22].
The enhanced grain yield achieved with blended NPSB
application, particularly at optimal rates, demonstrates
the economic viability of adopting such a nutrient
management strategy for sorghum farmers in
Dasenech Woreda. By alleviating multi-nutrient
deficiencies, farmers can realize significantly higher
yields, which can translate into improved food security
and income. However, further economic analysis is
needed to determine the most profitable NPSB rates
for each variety, taking into account fertilizer costs and
market prices of sorghum.
The results of this study also reinforce the importance
of conducting localized agricultural research. While
national fertilizer recommendations provide general
guidance, site-specific studies like this one are crucial
for fine-tuning recommendations to suit particular
agro-ecologies, soil types, and farming systems [8]. The
lowland, irrigated conditions of Dasenech Woreda
present a unique set of challenges and opportunities,
and the findings provide valuable data for developing
targeted best management practices.
CONCLUSION
This study clearly demonstrates that both sorghum
variety selection and the judicious application of
blended NPSB fertilizer are critical factors influencing
the growth, yield components, and ultimate grain yield
of sorghum cultivated under irrigated conditions in
Dasenech Woreda, Southern Ethiopia. The significant
and positive response to increasing NPSB rates
underscores the prevalent multi-nutrient deficiencies
in the region's soils, affirming the necessity of balanced
fertilization for optimal sorghum productivity.
Crucially, the highly significant interaction between
sorghum varieties and NPSB fertilizer rates highlights
that the maximum benefits from fertilizer application
are achieved when specific varieties are matched with
their optimal nutrient levels. This indicates that tailored
fertilizer recommendations are required to unlock the
full genetic potential of different sorghum varieties in
this specific irrigated environment.
Based on these findings, it is recommended that
farmers in Dasenech Woreda adopt blended NPSB
fertilizer application as a key strategy to enhance
sorghum yields. Future research should focus on
further refining these recommendations through
economic analysis to identify the most profitable NPSB
rates for each promising sorghum variety. Additionally,
long-term studies are warranted to assess the residual
effects of NPSB application on soil health and fertility,
ensuring the sustainability of enhanced sorghum
production systems in the region. The findings
contribute significantly to developing more precise and
effective agricultural extension packages for sorghum
growers in similar lowland irrigated agro-ecologies of
Ethiopia.
REFERENCES
Amalfitano CA, Del Vacchio LD, Somma S, Cuciniello AC,
Caruso G. Effects of cultural cycle and nutrient solution
electrical conductivity on plant growth, yield and fruit
quality of ‘Friariello’pepper grown in hydroponics.
Hortic Sci. 2017 May 11;44(2):91-8.
Azrag AA, Dagash YM. Effect of sowing date and
nitrogen rate on growth, yield components of sorghum
(Sorghum bicolor L.) and nitrogen use efficiency. J Pro
Res Bio. 2015;2(2):78-87.
Sibhatu B, Belete K, Tessema T. Effect of cowpea
density and nitrogen fertilizer on a sorghum-cowpea
intercropping system in Kobo, northern Ethiopia. Int
JAgric and For. 2015;5(6):305-17.
Caruso G, Stoleru VV, Munteanu NC, Sellitto VM,
Teliban GC, Burducea M, et al. Quality performances of
sweet
pepper
under
farming
management.
NotulaeBotanicaeHortiAgrobotanici
Cluj-Napoca.
2019;47(2):458-64.
CSA. (Central Statistic Authority) (2015). Report on area
and production of crops. Statistical Bulletin 578. Addis
Ababa: Ethiopia.
CSA, (2017). Central Statistical Agency, Agricultural
sample survey. Statistical bulletin 584April, 2017. Addis
Ababa.
Chimdessa D. Blended fertilizers effects on maize yield
and yield components of Western Oromia, Ethiopia.
AgricFor Fish. 2016;5(5):151-62.
Ethio-SIS (Ethiopia Soil Fertility Status). (2016).
Fertilizer Recommendation Atlas of the Southern
Nations, Nationalities and Peoples’ Regional State,
Ethiopia. Pp 81.
FAO (Food and Agricultural Organization), (2018).
Database of agricultural production FAO Statistical
9+Databases (FAOSTAT).
Gebrelibanos G, Dereje A. Nitrogen fertilization effect
on grain sorghum (Sorghum bicolor L. Moench) yield,
yield components and witchweed (Strigahermonthica
(Del.) Benth) infestation in Northern Ethiopia. IntJ Agric
Res. 2015;10(1):14-23.
Etana G. Effect of NPSB Blended Fertilizer on Growth,
Yield and Quality of Orange Fleshed Sweet Potato
(Ipomoea batatas(L.) Lam) Varieties under Jimma
American Journal Of Agriculture And Horticulture Innovations
6
https://theusajournals.com/index.php/ajahi
American Journal Of Agriculture And Horticulture Innovations (ISSN: 2771-2559)
Condition, South West Ethiopia.MSc. Thesis Jimma
University College of Agriculture and Veterinary
Medicine; 2018.
