International Journal of Horticultural Science 2023, 29: 37-45.

https://doi.org/10.31421/ijhs/29/2023/12499

Effects of biochar and inorganic fertiliser on the growth

and yield of beetroot (Beta vulgaris L.) in Kenya
Kwizera, E., Opiyo, A. M. & Mungai, N. W.
Department of Crop, Horticulture, and Soils, Faculty of Agriculture, Egerton University, P.O. Box 536-20115, Egerton, Kenya
Author for correspondence: kwizeraenock35@gmail.com

Summary: Beetroot (Beta vulgaris L.) is a root vegetable packed with many nutritional benefits such as minerals and vitamins. Despite its
importance in Kenya, farmers get about 30-35 t/ha which is significantly lower than the potential yield (68 t/ha). This is mostly attributed to low soil
fertility. This study aimed to determine the response of the beetroot growth and yield on biochar and NPK. A 3×4 factorial experiment was carried
out at Egerton University farm over two seasons to test the effects of biochar and NPK (17-17-17), under supplemental irrigation. Biochar (0, 5, 10
t/ha) was combined with NPK (0, 200, 300, 400 kg/ha). The combination of Biochar and NPK increased significantly (p ≤ 0.05) beetroot growth and
yield in two seasons. Treatment B10N400 showed the tallest plants (79.2 cm) at 90 days in season two, while the control resulted in the shortest
(27.6 cm). Treatment B10N200 showed the biggest (213.2 cm2) leaves at 90 days. The treatment B5N300 recorded the highest marketable yield (84
t/ha) in season two and the lowest was B0N0 with 2.6 t/ha. Sole application of NPK rates (200, 300, 400 kg/ha) increased significantly the growth
and yield of beetroot compared to the control in both seasons. In season one, N300 (300 kg/ha) had 61.9 t/ha of the total yield, the control had the
lowest. In season two, 300 kg/ha had 83 t/ha of total yield. Biochar increased beetroot growth and yield in season 2. Treatment B5 recorded the
highest marketable yield of 61.2 t/ha, while the control showed the lowest of 53 t/ha.

Kwizera, E., Opiyo, A. M., Mungai, N. W. (2023): Effects of biochar and inorganic fertiliser on the growth and yield of beetroot
(Beta vulgaris L.) in Kenya. International Journal of Horticultural Science 29: 37-45. https://doi.org/10.31421/ijhs/29/2023/12499

Key words: beetroot (Beta vulgaris L.), biochar, growth, NPK, soil amendment, yield

Introduction
Beetroot (Beta vulgaris L.) is a vegetable that has an origin Kenyan farmers get low beetroot growth and yield (30-35 t/ha),
in Germany. It belongs to the family of Chenopodiaceae which is far below the 68 t/ha (Omara et al., 2022) potential
(Yordanova & Gerasimova, 2016). Although it is typically yield of the crop. This is because farmers tend to apply
grown as an annual crop, beetroot is biennial (Pandita et al., inappropriate fertilisers due to their high cost and demand
2020). Beetroot is an important crop in Kenya due to its which lead to low soil fertility. Since synthetic fertilizer is very
economic and health benefits among small-scale farmers expensive, farmers are forced to use organic manure to increase
(Muthini et al., 2020a). It has shown tremendous importance in beetroot development. It is still difficult because they do not
human health such as cancer prevention and regulation of have enough information on the beetroot fertilisation process
blood pressure (Pandita et al., 2020). This is due to its mineral (Musyoka et al., 2019). However, this is a challenge in Kenya,
content and antioxidant properties. Beetroot can produce 40 because it makes the soil to become less fertile which leads to
tonnes per acre when proper farm management is applied food insecurity and poverty among small-scale farmers (Sileshi
(Vallespir et al., 2018). However, low soil fertility and leaching et al., 2019). Investigating sustainable methods to maintain soil
of nutrients which are major problems in sub-Saharan Africa fertility in East African countries to improve or maximize
(SSA), contribute to the decrease in beetroot productivity and potential agricultural output becomes crucial. To make this a
result in food scarcity (Tibesigwa et al., 2017). For instance, reality, the soil will need to be amended with a biologically
Jones et al. (2003) and Oladele et al. (2019) revealed that inert substance like biochar, known for its ability to stabilise
population increase, climate change and the tremendous nutrients in the soil and improvement of soil aggregation
pressure on the soil to boost crop productivity lead to low (Arfaoui et al., 2019). Biochar is the end product of the
production of the crop. Beetroot performs better under cool pyrolysis process (burning of agricultural waste and biomass in
climate conditions and can also be cultivated successfully anaerobic conditions) (Zhang et al., 2020). However, its
nearly all year round. It is more popular in Nakuru, Kiambu, application can be a solution to the low soil fertility problem in
and Tharaka-Nithi counties in Kenya (Muthini et al., 2020b). East African countries like Kenya (Simms et al., 2020).
Beetroot requires macronutrients (nitrogen, phosphorus and Biochar's chemical and physical properties make it
potassium) and micronutrients (zinc, boron) to be available in appropriate for application as a soil amendment and contribute
the soil for its development (Omara et al., 2022). This is why, to carbon sequestration (Weidemann et al., 2018; Rasafi &
without the use of organic materials and inorganic fertiliser, Haddioui, 2020). Biochar application improves the pH, soil
prospective beetroot potential yield is no longer possible structure, water-holding capacity and bulk density (Sahoo &
(Wada et al., 2022). More so, Kimani et al. (2021) stated that Remya, 2022). Previous studies including Usevičiūtė &
38 Kwizera et al.

Baltrėnaitė (2021); Knoblauch et al. (2021); Zhang et al. at three levels of 0, 5 and 10 t/ha and four levels of 0, 200, 300,
(2020) and Abhilash et al. (2016) also have demonstrated that and 400 kg/ha respectively, giving 12 treatment combinations
the application of biochar with NPK improves the growth and (Table 1). The land was prepared on the 25th and 26th of
yield of the crops. This is a result of improved nutrient use February, 2021 for season one. In season two, the land was
efficiency (Mondal et al., 2022). Despite this highlighted prepared from the 28th and 30th of July using conventional
importance, in Kenya, studies of biochar and chemical fertiliser tillage tools. In every experimental plot, biochar was mixed
(NPK) to improve the growth and yield of beetroot are missing, with the soil with the use of a hoe and rake in the
so this is the first experimental field on the topic. In this corresponding plots. Before planting, the different rates of
regard, this research was designed to assess the effects of NPK were also applied in the corresponding experimental
acacia charcoal dust (Biochar), and NPK fertiliser and their plots. The seeds of ‘Detroit's dark red’ were drilled uniformly
interaction on beetroot growth and yield. into the rows within the plots, followed by thinning after two
weeks after planting to maintain plant spacing.
Materials and methods
Table 1. Treatment combinations

Site description Treatment Biochar level NPK levels TRT

(TRT) (t/ ha) (kg/ ha) combinations*
1 0 0 B0N0
The study was conducted at the Horticulture Research Field
Three at Egerton University, Njoro, Kenya. The site lies at a 2 5 0 B5N0
latitude of 0o 23’ S, a longitude of 35o 35’ E at an altitude of 3 10 0 B10N0
2238m above sea level. It is in agroecological zone III of 4 0 200 B0N200
Kenya. The site receives annual precipitation of approximately 5 0 300 B0N300
1000 mm with average temperatures of 16 oC to 22 oC
6 0 400 B0N400
(Jaetzold et al., 2012). The major soil type in this experimental
area is Mollic Andosols, characterised by a dark to black 7 5 200 B5N200
colour, moderate organic matter and low phosphorus content 8 10 200 B10N200
(Jaetzold et al., 2012). The site provided suitable conditions for 9 5 300 B5N300
beetroot growth. The experiment was conducted in two 10 10 300 B10N300
seasons, season one started on the 26th of March to the 23rd.
11 5 400 B5N400
June 2022 and the second started from 2nd August to 2nd
12 10 400 B10N400
November 2022 with supplement irrigation.
Where * B is the Biochar levels and N is the NPK levels
Soil analysis Crop management
Soil samples were collected at 0-20 cm depth using a Zig Weeds were controlled regularly by hand weeding
Zag method to represent the whole field. Seven samples were throughout the growth period to keep the crops free of weeds.
collected by the soil auger and a bucket was used to carry the Whenever insect pests appeared cypermethrin 25% EC was
samples and allow easy mixing to get a composite sample for sprayed and it has been sprayed thrice to control pests after
analysis. The samples were air-dried and passed through a planting. The crop was rain-fed with supplemental irrigation
2mm sieve to remove roots and stones. Total nitrogen was provided during dry spells using a drip irrigation system. The
determined by the use of the Kjeldahl method (Anglov et al., growth parameters (number of leaves, plant height and leaf
2003) and Mehlich Double Acid was used to analyse area index) were measured 30, 45, 75 and 90 days after
phosphorus, potassium, sodium, calcium, magnesium and planting in each season on 8 sample plants in the middle rows.
manganese (Okalebo et al., 2002). Soil pH was measured The number of leaves was counted manually. A meter ruler
using a pH meter at a soil: water ratio of 1:1 (volume/volume). was used to measure the plant height starting at the base of the
Organic carbon was analysed using the Walkey and Black plant to the leaf apex. The length (from the end of the petiole to
method as described by Okalebo et al. (2002). the leaf apex) and width from the right margin to the left
margin of the average leaf were measured to estimate the leaf
Biochar production
area index and it was estimated using the formula 𝐿𝐴 =
𝘓 × 𝘞 × 0.75 developed by Varga et al. (2021). Where L is
Biochar which was obtained from Cooks Well Company in
the length of the leaf and W is the width of the leaf and 0.75 is
Nairobi, Kenya, was the waste product of mostly acacia trees
the correction factor. The harvesting of the sample plants in the
through the pyrolysis process. The temperature used to burn the
middle rows in each respective plot was done after 3 months in
acacia trash is 250 oC and the process of burning took
every season; it was done by uprooting the tubers from the soil
approximately one hour and fifteen minutes.
and removing the soil by the use of hands. A portable
electronic weighing balance (EK300I-JA 300 g, AND, Beijing,
Experimental layout
China) was used to measure the weight of the roots from the
sampled plants in the middle rows to determine the yield of
The study was set in a randomized complete block design
beetroot in each plot.
in a factorial experiment with two factors (3×4) replicated three
times. Each block had twelve (12) treatments. Each plot was
Statistical analysis
1.8×1.6 m2 with six rows, the spacing between rows was 30 cm
and the spacing between plants within the same row was 20
The data obtained from this study were tested for normality
cm. Biochar and inorganic fertiliser (NPK) were each applied
using the Shapiro-Wilk test. They were subjected to the
Effects of biochar and inorganic fertiliser on the growth and yield of beetroot (Beta vulgaris L.) in Kenya 39

analysis of variance using the SAS 9.4 General Linear Model

(GLM) technique (Hodges et al., 2022) to check the significant Season one
60,0
difference between treatments. Where treatments were found
significant, means separation for the sole effects and of biochar

Plant height (cm)

and NPK as well as their interaction was done using Tukey's 40,0
Honestly Significant Difference at p ≤ 0.05.
20,0
Results and discussion
Soil and biochar analysis 0,0
30 45 60 75 90
Laboratory analysis results revealed that the biochar used in Days after planting
this study was alkaline because it was having high pH (8.3). 0 t /ha 5 t /ha 10 t /ha
The alkalinity properties of biochar were because it contained
high ash concentration which had high magnesium, calcium, Figure 1a. Effects of biochar on beetroot plant height.
potassium and carbon content and also based on the results
from the laboratory it was clear that soil had low phosphorus Season two
content (Table 2).
80,0

Plant height(cm)
Table 2. Initial Characterization of soil and biochar.
60,0
Parameters Soil Biochar
40,0
0-20 cm
20,0
pH (H2O) 5.7 8.3
Total nitrogen % 0.3 0.1 0,0
30 45 60 75 90
Organic carbon % 2.8 3.1
Days after planting
Available phosphorus (cmol/kg) 20.0 0.6
Potassium (cmol/kg) 1.2 0.7
0 t/ ha 5t/ ha 10 t /ha
Calcium (cmol/kg) 5.2 3.3
Magnesium (cmol/kg) 3.1 0.1
Figure 1b. Effects of biochar on beetroot plant height.
Manganese (cmol /kg) 0.4 663.0
Copper (cmol/ kg) 1.0 8.3
60
Season one
Iron (cmol /kg) 114.0 1343.0
Zinc(cmol/kg) 11.2 76.7 50
Sodium (cmol/kg) 0.6 not determined
40
Plant height (cm)

Effects of biochar and NPK on beetroot height 30

20
The different applied combined rates of fertilizers (biochar
and NPK) significantly increased the beetroot height at p≤0.05 10
at 75 days and 90 days after planting in season two. At 75 days,
0
the treatment B5N200 showed the tallest plants at 42.1 cm on 30 45 60 75 90
average, while B0N0 had the shortest plants at 22.5 cm. The Days after planting
plots that received treatment B10N400 showed the tallest plant 0 kg /ha 200kg /ha 300kg /ha 400kg /ha
averaged 79.2 cm and the control recorded the smallest average
of 27.6 cm at 90 days (Table 3). The observation showed that Figure 1a. Effects of NPK on the beetroot plant height.
the sole application of biochar at different rates increased
significantly the growth of beetroot in season two, but there Season two
was no significant difference in season one. In season two, 60
treatment B10 showed the tallest plant averaging 59.6 cm,
followed by B5 averaging 46.3 cm and the control showed the
Plant heihgt (cm)

shortest averaging 38.1 cm at 90 days (Figure 1a-b). On the 40

other hand, the sole application of NPK also recorded a
significant increase in beetroot height in both seasons. In
season one, the different rates of NPK (200, 300, and 400 20
kg/ha) were not statistically different, but statistically different
compared to the control. In season two, at 45, 60, 75 and 90
0
days after planting. In season two, the rates of NPK were
30 45 60 75 90
statistically different from each other at 75 days. The plots that
Days after planting
received NPK at 300 kg/ha produced the tallest plants
0 kg /ha 200kg/ ha 300kg/ ha 400kg /ha
averaging 42.2 cm, while the shortest plants were observed in
the control treatment averaged 23 cm (Figure 2a-b).
Figure 2b. Effects of NPK on the beetroot plant height.
40 Kwizera et al.

Table 3. Effects of co-application of biochar and NPK on beetroot plant height.

Biochar NPK Season one Season two
Days after planting Days after planting
t/ha kg /ha 30 45 60 75 90 30 45 60 75 90
0 0 6.1 15.8 26.8 32.1 31.5 6.2 7.6 18.1 22.5cd 27.6e
0 200 8.6 19.6 34.9 39.1 41.1 7.8 13.8 24.1 40.2ab 43.5ed
0 300 8.2 17.5 31.0 38.7 39.8 8.0 14.0 26.7 40.2ab 40.8ecd
0 400 8.4 16.9 29.9 37.9 39.7 8.7 14.5 26.6 36.8b 40.4ecd
5 0 6.3 16.2 28.0 37.0 37.8 6.0 8.1 18.5 18.5d 28.7e
5 200 9.2 20.2 34.3 43.4 44.9 8.1 14.7 24.1 42.1ab 53.4bcd
5 300 8.3 19.4 34.2 45.9 46.7 6.8 12.5 25.9 46a 46.7bcde
5 400 7.1 16.9 29.2 41.3 42.5 7.3 14.5 24.9 40.0ab 56.4abc
10 0 6.3 13.7 23.8 32.1 36.8 6.2 8.7 17.4 27.8c 33.2ed
10 200 6.9 18.1 32.3 41.9 42.7 6.3 11.8 24.6 41.2ab 58.3abc
10 300 6.3 20.3 35.2 43.1 46.0 7.2 13.5 24.9 40.2ab 67.6ab
10 400 8.2 20.2 35.4 42.5 45.0 7.1 12.5 25.2 39.0ab 79.2a
Significance NS NS NS NS NS NS NS NS ** *
NS: Not significant; *significant at p>0.05; ** significant at p>0.01
Means in the same column with the same letter are not significantly different at p≤0.05.

Table 4. Effect of the interaction of biochar and NPK on the beetroot leaf area.
Leaf area
Biochar NPK Season one Season two
Days after planting Days after planting
T/ ha kg /ha 30 45 60 75 90 30 45 60 75 90
0 0 5.6 26.4 80.0 116.0 119.7 3.4 8.2 48.4 70.7d 81.8d
0 200 13.1 56.0 122.3 183.5 184.5 4.7 29.3 104.5 157.6c 121.7cd
0 300 12.0 56.8 119.8 190.6 188.7 5.7 24.7 120.2 162.2cb 140.3cb
0 400 11.6 58.4 119.1 186.6 194.9 6.9 30.3 96.0 162.1cb 149.1cb
5 0 11.0 39.9 101.0 156.2 157.8 3.1 9.1 52.7 61.3d 82.7d
5 200 14.6 56.2 125.5 198.0 199.3 6.8 36.4 112.4 182.7abc 193.6ab
5 300 13.2 64.3 165.1 209.2 227.0 5.1 21.1 101.0 189.7abc 187.5ab
5 400 8.9 48.3 121.2 196.7 197.8 6.0 33.8 112.3 186.4abc 189.0ab
10 0 7.0 31.3 81.2 134.3 137.6 3.0 12.4 55.3 75.6d 105.2cd
10 200 11.6 54.8 115.1 205.3 208.0 3.9 21.5 104.5 211.7a 213.2a
10 300 12.2 67.4 155.1 193.5 212.9 5.2 31.2 113.3 193.2ab 204.5a
10 400 11.2 68.3 122.3 180.4 182.3 5.5 24.5 91.3 190.8abc 193.0ab
Significance NS NS NS NS NS NS NS NS * *
NS: Not Significant; *significant at p>0.05
Means with the same letter within the column are not statistically different at p≤0.05

Leaf area where B10 showed the highest leaf area index averaging 167.8
cm2 at 75 days after panting. The treatments B5 and B10 were
The combined application of biochar and NPK significantly not statistically different from each other, but different from the
increased the leaf area of beetroot in season two, at 75 and 90 control at 90 days (Figure 3a-b). In season one, the sole
days after planting. The treatment B10N200 recorded the applications of NPK at the different rates (200, 300, 400kg/ha)
biggest leaves (211.7 cm2), while B0N0 resulted in the smallest were not statistically different from each other but were
leaves (70.7 cm2) at 75 days. At 90 days B10N200 showed the statistically different from the control at 30, 75, and 90 days
biggest leaves (213.2 cm2) while B0N0 resulted in the smallest after planting. But the trend was not the same at 60 days. The
leaves (81.8 cm2) (Table 4). The sole application of biochar application of NPK at 300kg/ha recorded the biggest leaves
significantly increased the leaf area in season one at 90 days averaging 146.7 cm2 followed by the treatments NPK at 200
after planting and at 75, and 90 days in season two. The kg/ha and 400 kg/ha, which were not statistically different from
treatment B5 was not statistically different from B10 but each other. The control recorded the smallest leaves averaging
significantly different from the control and recorded an average 87.4 cm2. In season two, the rates of NPK were not statistically
leaf size of 195.5 cm2, which was the largest leaf size among different from each other but different from the control,
the others. In season two, B5 and B10 were statistically throughout the season (Figure 4a-b).
different from each other, and also different from the control,
Effects of biochar and inorganic fertiliser on the growth and yield of beetroot (Beta vulgaris L.) in Kenya 41

Season one Season one

300,0
60
50 16,49

Yield (t/ha)
17,49
Leaf area (cm2)

200,0 40 17,44
30
20 37,47 39,73
100,0 32,34
10
0
0t/ha 5t/ha 10 t/ha
0,0
30 45 60 75
Biochar rates
Days after planting
0t/ha 5t/ha 10t/ha Marketable Yield Non Marketable Yield

Figure 3a. Effect of biochar on the beetroot leaf area. Figure 3a. Effect of biochar on the beetroot yield.

Season two Season two

80
200,0
70
Leaf area (cm2)

9,25
60 15,31 11,08

Yield (t/ha)
50
100,0 40
30 61,15 56,18
52,99
20
0,0 10
30 45 60 75 90 0
0t/ha 5t/ha 10 t/ha
Days after planting
Biochar rates

0t/ha 5t/ha 10t/ha Marketable Yield Non Marketable Yield

Figure 3b. Effect of biochar on the beetroot leaf area. Figure 4b. Effect of biochar on the beetroot yield.

250,0 Season one Season one

Leaf area (cm2)

200,0 80
Yield (t/ha)

150,0 60
16,58 17,00 17,05
100,0 40
17,93
50,0 20 40,53 44,87 40,27
20,38
0,0 0
30 45 60 75 90 0kg/ha 200kg/ha 300kg/ha 400kg/ha
Days after planting
NPK rates
0kg/ha 200kg/ha 300kg/ha 400kg/ha
Marketable Yield Non Marketable Yield

Figure 4a. Effect of NPK on the beetroot leaf area. Figure 5a. Effects of NPK on the beetroot yield.

Season two Season two

100
250,0
Leaf area (cm2)

80 8,73
200,0
Yield (t/ha)

9,35 8,54
150,0 60

100,0 40 20,90 74,31

61,07 62,27
50,0 20
29,44
0,0
30 45 60 75 90 0
0kg/ha 200kg/ha 300kg/ha 400kg/ha
Days after planting
NPK rates
0kg/ha 200kg/ha 300kg/ha 400kg/ha Marketable Yield Non Marketable Yield

Figure 4b. Effect of NPK on the beetroot leaf area. Figure 6b. Effects of NPK on the beetroot yield.
42 Kwizera et al.

Table 5. Effect of the interaction of biochar and NPK on the total yield of beetroot.

Biochar NPK Total yield Marketable yield Non-marketable yield

t /ha kg /ha Season 1 Season 2 Season1 Season 2 Season1 Season2

0 0 33.0 46.3 16.0 2.6c 17.0 43.8a

0 200 54.6 78.0 38.2 71.7ab 16.4 6.3b
0 300 56.1 73.9 38.4 66.3ab 17.7 7.6b
0 400 55.4 75.0 36.7 71.4ab 18.7 3.6b
5 0 44.1 56.9 25.3 48.3ab 18.8 8.7ab
5 200 59.9 67.5 43.3 60.1ab 16.6 7.4ab
5 300 61.8 94.4 44.2 84.0a 17.6 10.3b
5 400 54.0 62.8 37.2 52.2ab 16.9 10.6ab
10 0 37.7 47.8 19.8 37.5b 17.9 10.3ab
10 200 56.9 65.8 40.1 51.4ab 16.7 14.4b
10 300 67.7 80.8 51.9 72.6ab 15.8 8.2ab
10 400 62.6 74.7 47.1 63.2ab 15.6 11.5ab

Significance NS NS NS *** NS **
NS: Not significant; ** significance at p>0.01; *** significance at p>0.001
Means with the same letter in the column are not statistically different at p≤0.05

Effects of biochar and NPK on the yield of beetroot findings were reported by Walter & Rao (2015) who reported
an increase in the height of sweet potatoes after combining
The combined application of biochar and inorganic biochar at 7 and 12 t/ha with inorganic fertilisers at 350 and
fertilizer (NPK) did not show a significant increase in the total 500 kg/ha and they attributed this growth to biochar's capacity
yield of beetroot in both seasons one and two. However, the to improve microbial activity and increasing soil aeration
co-application of biochar and NPK had a significant effect on which allows root penetration to absorb beneficial nutrients to
the marketable and non-marketable yield of beetroot in season the plant. Results by Oladele et al. (2019) in Nigeria also
two. The treatment B5N300 recorded the highest average of revealed an increase in the growth of rice when biochar was
84 t/ha, and the control recorded the lowest average of 2.6 t/ha combined with urea at 450 kg/ha. Similarly, Hamzah &
(Table 5). On the other hand, the B0N0 recorded the highest Shuhaimi (2018) reported that when biochar at 8 t/ha was
non-marketable yield averaging 43.8 t/ha, and the B0400 combined with nitrogen fertilizers (NPK) at 300 kg/ha, maize
recorded the lowest average of 3.6 t/ha. The sole application of plants grew taller when compared to the control. Similar results
biochar increased significantly the marketable yield in season were reported by Arif et al. (2017) who documented a
2. The Plots that received biochar at 5 t/ha (B5) recorded the significant increase in the height of maize after the application
highest average of 61.2 t/ha, and the control showed the lowest of the combined biochar and chemical fertiliser. They
average of 53 t/ha (Figure 5a-b). On the other hand, the attributed their results to the ability of biochar to recycle
application of NPK at the rates of 200, 300 and 400 kg/ha organic matter in the soil. They have also reported that biochar
significantly increased the total yield of beetroot compared to as a soil amendment contributes to the absorption of heavy
the control (0 t/ha) in seasons one and two. The plots that metals in agricultural soil. This explains clearly that biochar
received 300 kg/ha of NPK recorded the highest total yield of combined with inorganic fertilizer provided more nutrients for
61.9 t/ha (Figure 6a-b) and a marketable yield of 44.8 t/ha in growth. This is because biochar applied as the soil amendment
season one. In season two, the application of NPK (300 kg/ha) has the potential to improve some of the soil's chemical
recorded a total yield of 83 t/ha and a marketable yield of 74.3 properties like pH, organic matter (OM), and microbial
t/ha. The control recorded the lowest total yield in both seasons activity. As a consequence of the change in chemical
one and two (38.3 and 50.3 t/ha respectively) and marketable properties, key soil processes like carbon mineralization and
yield (20.9 and 29.4 t/ha respectively) (Figure 6a-b). nutrient transformations could be increased in the soil (Summa
et al., 2021).
Discussion Studies by Pandian et al. (2016) and Ghorbani et al., (2019)
demonstrated the synergistic impact between biochar and
Effects of biochar and NPK on beetroot growth inorganic fertilisers in promoting crop growth. The utilisation
of biochar together with inorganic fertiliser demonstrated a
Plant height and leaf area were greatly influenced by the great impact to increase beetroot growth due to its capability to
sole application recommended rate of NPK or its combination increase the soil's macro and micronutrients as well as soil
with biochar at 5 and 10 t /ha. Moreover, the combination of texture. Both B5N300 and B10N300 recorded a significant
biochar at 5 and 10 t/ha with all the rates of NPK (0, 200, 300, increase in beetroot growth. However, B10N300 improved
400) performed better than the sole application of biochar or growth more than B5N300 and this could be attributed to the
NPK. This is because combining biochar with inorganic amount of nutrients made available by the increase of biochar
fertilizer has a synergistic impact, which contributes to the from B5N300 to B10N300. Another reason for the increase in
improvement of nutrient absorption by plant roots. Similar beetroot height after the application of biochar and NPK could
Effects of biochar and inorganic fertiliser on the growth and yield of beetroot (Beta vulgaris L.) in Kenya 43

be due to its large surface area of biochar which might provide t/ha) and NPK rates (200, 300, 400 kg/ha) on beetroot
a conducive environment for beneficial micro-organisms to production can be attributed to the ability of biochar and NPK
grow. This affects several processes in the soil like N cycling to supply nutrients to beetroot plants, condition the soil and
which improves fertility. Inorganic fertiliser NPK provided the increase fertiliser-use-efficiency of the beetroot cultivar in this
nutrients needed for beetroot growth as seen by both the leaf study (Ahmed & Schoenau, 2015).
area and plant height. Inorganic fertilisers have more nutrients
easily available for plants. Hence, the application of N200 did Conclusions
not increase beetroot growth as N300 and N400 because of the
reduced supply of nutrients. The application of 5 or 10 t/ha This research’s findings prove that adding biochar to the
biochar alone increased beetroot growth with time; this might soil could help enhance beetroot growth and yield, provided
be explained by the biochar's ability to reduce soil bulky that it is combined with NPK fertiliser. In comparison with the
density to allow deep penetration of the roots for nutrient application of sole synthetic fertiliser (NPK), biochar at (5-10
absorption. Findings by Carpenter & Nair (2014) revealed that t/ha) and NPK fertiliser at (200, 300 and 400 kg/ha)
the utilisation of charcoal dust as the soil conditioner increased contributed better to the increase of the growth and yield of
the growth of the carrots with time and they attributed this to beetroot. The combination of biochar at 5 t/ha and 300 kg/ha of
the increase of macronutrients and the type of biochar. An NPK can be recommended to the farmers and other
increase of sole biochar from B5 to B10 resulted in an stakeholders involved in beetroot production. This is because it
improvement in beetroot growth because of the rise in nutrient indicated the highest yield compared to the other treatments.
content.
Acknowledgements
Effects of biochar and NPK on the yield of beetroot
This study was funded by the MasterCard foundation
The application of charcoal dust (biochar) and inorganic through RUFORUM to “Transforming African Agricultural
fertiliser (NPK) significantly increased the yield of beetroot. Universities to meaningfully contribute to Africa’s Growth and
The results from this study recorded a slight increase in the Development (TAGDev)” Programme at Egerton University
growth and yield of beetroot with a sole application of biochar.
This is validated by Manka et al. (2019) who documented a
slight increase in the yield of carrots when biochar was applied
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