Responses of Sorghum to
Combined Application of A
Nutrient Solution and Solid
NPK Fertilizers in a Tropical
Environment
BY
B. O. UKEM
DEPT. OF SOIL SCIENCE, FACULTY OF
AGRICULTURE/INSTITUTE FOR
AGRICULTURAL RESEARCH, AHMADU
BELLO UNIVERSITY, ZARIA, NIGERIA
Introduction

In the savanna soil of Nigeria, micronutrient deficiency was not noticed in the past but
with the intensification of agriculture over the years, crop exploitation of soil available
nutrients, crop removal and adverse cultural practices of farmers have led to the
incidence of micronutrient deficiency with negative effect on growth, yield and quality of
crops.

Sorghum (Sorghum bicolor) cultivation in Nigeria has continued to rise over the years
particularly in the last decade with an estimated land area of about 6 – 6.5 million
hectares cropped to sorghum annually and farmers yields have risen tremendously from
about 3.8 – 6.8 million metric tons of dry grains from the land area under cultivation
(NBS, 2010).

With limited land resources, the impact of continuous cultivation has contributed
adversely to the rapid depletion and imbalances of soil plant nutrients which
consequently poses a serious threat to the soil fertility status and thereby limiting
sustainable crop production practices.

The micronutrients present in the NPK fertilizers are mainly as incidental elements.
Also, their fixation with phosphate anions in the soil often renders them unavailable to
plants which therefore necessitates foliar application of a nutrient solution to enhance
micronutrients availability for crop use.
The objectives of the study are:
1.
To test the effectiveness of Algifol nutrient solution
as a single fertilizer and in combinations with solid
NPK on growth and yield of sorghum under
tropical conditions.
2.
To test the effect of single and combined application
rates of Algifol nutrient solution and NPK on
growth and yield of sorghum.
3.
To determine the optimum application rate of
Algifol nutrient solution in the northern guinea
savanna of Nigeria.
Materials and Method
Study Area:

The experiment was conducted at the Institute for Experimental Res. Samaru Located in the
Northern Guinea Sav. agro-ecological zone of Nigeria .
Soil Characteristics:

Soil of the zone is classified as Alfisol Ojanuga (1979). The soil is low in organic matter content, total
N and available P but moderate in exchangeable bases. Clay mineralogy is of low activity.

Soil is therefore low in fertility.

Soil data is in Table 1. nutrient composition of Algifol is in Table 2
Fertilizer Rates,Treatments and Design:

Algifol nutrient solution rates were 5, 10, 15 and 20ml/100ml of water(1/2, 1, 11/2 and 2Alg) or 0.5, 1.0,
1.5 and 2.0 litres/ha Algifol and ¼, ½, ¾ and 1 or Full NPK at the rate of 150, 60, 60kg/ha N, P2O5
and K2O respectively.

solid fertilizer levels were ¼NPK, ½NPK, ¾NPK and Full NPK at the rate 64:32:30kg ha-1 N, P2O5
and K2O representing (16, 8, 7.5, kg ha-1 N, P2 O5 and K2O); (32, 16, 15 kg ha-1 N, P2 O5 and K2O);
(48, 24, 22.5, kg ha-1 N, P2 O5 and K2O) and (64, 32, 30 kg ha-1 N, P2 O5 and K2O). Urea, Single
Superphosphate (SSP) and Muriate of Potash (MOP) were the fertilizer materials used. Nitrogen was
split applied in bands at 2WAP and 8WAP. SSP and MOP were band applied at planting.

The treatments were laid in a Randomized Completely Blocked Design (RCBD) with three
replications.

Table 2 Chemical composition of Algifol nutrient
solution
Chemical Components
Values
Phosphorus (mg kg-1)
9.88
Potassium (cmol kg-1)
3,268
Calcium (cmol kg-1)
647
Sodium (cmol kg-1)
600
Zinc (mg kg-1)
3.75
Iron (mg kg-1)
20.00
Manganese (mg kg-1)
6.25
Copper (mg kg-1)
2.50

Table 3 Physico-chemical characteristics of soil from the
experimental site (20cm soil depth)
Soil Property
Sand (g
Values
kg-1)
371
Silt (g kg-1)
400
Clay (g kg-1)
229
Textural Class
Loam
pH (1:2.5 w/v H2O)
5.0
PH (1:2.5 w/v, 0.01M CaCl2)
4.7
Organic Carbon (g
kg-1)
5.4
Total N (g kg-1)
1.27
Bray - 1 Available P (mg kg-1)
2.69
kg-1)
3.60
Exchangeable Mg (cmol kg-1)
0.39
Exchangeable K (cmol kg-1)
0.47
Exchangeable Na (cmol kg-1)
0.21
CEC (cmol kg-1)
4.67
Exchangeable Ca (cmol
Extractable Zn (mg
kg-1)
6.8
Extractable Fe (mg kg-1)
18.0
Extractable Cu (mg kg-1)
2.0
Extractable Mn (mg
kg-1)
18.0
Results and Discussion
Plant Height

The response of plant height to treatments is presented in Table 4. The results show
that the treatments had a significant effect(P=0.05) at 7WAP, but at 9WAP, the effect
was highly significant (P=0.01). It is obvious from the result that the fertilizer
treatments had a positive impact on the vegetative growth of the plant.

There was a positive response from the soil applied solid NPK doses at 9WAP
though the trend of increase in height was not consistent with treatments. The
complementary application of nutrient solution and NPK seemed to be nutritionally
more effective as best result was recorded from 1Alg + ¾NPK at 9WAP (Table 4).
This may be related to the rather low fertility conditions of the soil (Tarfa et al.,
2001).

From the results, control consistently recorded the shortest height in relation to
other treatments because of the low initial fertility level of the soil (Table 3). It is
therefore expedient to apply inorganic fertilizers in suitable combinations to boost
adequate vegetative growth.

Table 4 Effect of the nutrient solution and NPK on plant
height and girth
Plant height
Plant girth
cm
WAP
Trt rate
7
9
7
9
Control
218.06bc
335.05ef
6.43c
7.61f
½ Alg
338.09a
374.57b
6.66bc
8.39bcde
1 Alg
237.78abc
307.06g
7.05ab
8.90ab
1½ Alg
270.69ab
326.02f
6.47c
7.90def
2 Alg
222.93bc
333.09ef
6.99abc
8.77ab
¼ NPK
207.04bc
345.82de
6.88abc
7.89def
½ NPK
195.14bc
373.97b
7.16ab
8.02cdef
¾ NPK
220.35bc
329.05ef
7.05abc
7.85ef
Full NPK
196.28bc
362.78bc
6.97abc
9.02a
½ Alg + Full NPK
210.59bc
351.95cd
6.92abc
8.46bc
1 Alg + ¾ NPK
241.24abc
408.51a
6.98abc
7.94cdef
1½ Alg + ½ NPK
153.17c
283.82h
7.29a
9.24a
2 Alg + ¼ NPK
268.58ab
328.60f
6.97abc
8.42bcd
F ratio
*
**
*
**
SE 
33.78
5.33
0.17
0.17
Stem Girth
 Effect of the fertilizer treatments on stem girth was significant (P=0.05) at
7WAP and at 9WAP, the effect was highly significant (P=0.01) (Table 4). In
both periods, the control had the lowest girth compared to the positive
responses from the fertilizer treatments. The low response recorded from
control is attributed to the low fertility conditions of the soil. And as such,
amendments of the soil with either organic or inorganic sources of
nutrients should improve its nutrient holding status for efficient crop
performance.
 Complementary application of both nutrient solution and NPK made a
significant impact on the growth of sorghum in a tropical savanna soil having
been able to furnish the desired plant nutrients and in their suitable ratios
to meet crop requirements.
Grain Yield
 Grain yield responded positively and significantly (P=0.05) to the
treatments (Table 5). Response to nutrient solution levels alone showed a
significant increase from ½ rate Alg up to 1½ rate Alg with yield increases
ranging from 1162, 1308 to 1675kg ha-1 grains (37%, 39% to 45%) yield
respectively over the control (Table 5). The decrease in grain yield
recorded from 2 rate Alg may be due to leaf burning effect initiated by the
higher level of the nutrient solution and thereby leading to the destruction
of photosynthetic sites of the plant with a consequent yield reduction. A
similar effect had already been reported (Effiong et al., 2006; Brady and
Weil, 2005).
 The response from the treatment combinations showed that low levels of
nutrient solution in combination with higher levels of NPK were superior
to higher levels of nutrient solution combining with reduced levels of NPK.
It is therefore obvious that minimal levels of foliar solutions are more
efficient than the higher doses in plant nutrition especially in combination
with NPK doses.
Table 5 Effect of the nutrient solution and NPK on head,
grain and stover yields
Head
Grain
Stover
Yield (kgha-1)
Trt rate
Control
2,480c
2,016c
10,000c
½ Alg
4,196abc
3,178abc
12,333bc
1 Alg
4,052abc
3,324abc
11,000bc
1½ Alg
4,535ab
3,691ab
9,667c
2 Alg
3,167bc
2,507bc
11,833bc
¼ NPK
3,496abc
3,034abc
12,667bc
½ NPK
2,994c
2,410bc
14,667bc
¾ NPK
4,504ab
3,379abc
13,333bc
Full NPK
5,023a
4,062a
15,667b
½ Alg + Full NPK
4,140abc
3,634ab
15,500b
1 Alg + ¾ NPK
4,083abc
3,155abc
20,333a
1½ Alg + ½ NPK
3,113bc
2,541bc
9,833c
2 Alg + ¼ NPK
3,283bc
2,694abc
12,667bc
F ratio
*
*
**
SE +
514
418
1.53
Stover Yield

The effect of the fertilizer treatments on plant dry matter was highly
significant (P=0.01). Highest yield was obtained from the combined
application of 1Alg + ¾NPK while the least performance was
obtained from 1½Alg dose though its treatment mean was not
significantly different from the control (Table 5).

The result further shows that nutrient solution or NPK alone could
not achieve the expected DMY that was achievable with NPK +
nutrient solution, thus suggesting the need for an integrated system
of crop production that combines foliarly applied nutrient solutions
and soil applied NPK for the savanna soils.
Conclusion




The trial has revealed that in many parameters measured, control
recorded the lowest performance relative to actual fertilizer
treatments. It is evident from the results that fertilizer application
improved the growth and yield of sorghum in the northern guinea
savanna soil.
Even though full rate NPK recorded the highest grain yield, the
complementary application of nutrient solution and NPK was more
effective in achieving adequate plant height, girth and stover.
Such treatment combinations are optimum especially under tropical
conditions in ensuring a healthy crop growth and sustainable yields.
In view of the effective performance of the complementary
application of nutrient solution and NPK, there is therefore the need
to explore such combinations for a wider use in tropical soils.
THANK YOU