Research Article
Ann Agric Crop Sci. 2024; 9(2): 1150.
Effect of NPSB and N Fertilizer Rates on Yield and Yield Components of Black Cumin (Nigella Sativa L.) in the Midland Areas of Guji Zone, Southern Ethiopia
Arega Amdie*; Solomon Teshoma; Miressa Mitiku
Oromia Agricultural Research Institute (IQQO), Bore Agricultural Research Center (BOARC), Ethiopia
*Corresponding author: Amdie A Oromia Agricultural Research Institute (IQQO), Bore Agricultural Research Center (BOARC), Ethiopia. Email: aregahorti2@gmail.com
Received: January 12, 2024 Accepted: February 26, 2024 Published: March 04, 2024
Abstract
Black cumin (Nigella sativa L.) is one of the most important food security and cash crops in Ethiopia. However, its productivity is generally low. The low yields of the crop could be attributed to a number of factors, among which low soil fertility is an important constraint. There is little information on the types and rates of fertilizers to be applied, and the cropping system has been given attention to improve its production and productivity. Therefore, an experiment was conducted at the Kiltu Sorsa farmer field in Adola district during the 2021 and 2022 cropping seasons to determine the effect of blended NPSB and nitrogen fertilizer rates on black cumin and to assess the cost and benefit of different rates of blended NPSB and nitrogen fertilizers on black cumin. The treatments consisted of four rates of blended NPSB (0, 50, 100, and 150 kg NPSB/ha) and four rates of nitrogen (0, 23, 46, and 69 kg N/ha) fertilizers. The experiment was laid out as a Randomized Complete Block Design (RCBD) in a 4*4 factorial arrangement replicated three times. An improved black cumin variety called Silingo was used as a test crop. The two-year analysis of the data revealed that the interaction effects of blended NPSB and nitrogen fertilizers influenced significantly (P<0.05) days to 50% flowering, days to 90% maturity, plant height, number of capsules per plant, and seed yield. However, the two fertilizers did not interact to influence the number of seeds per capsule parameter of the crop. The highest seed yields were obtained with the application of 100 kg of blended NPSB/ha and 46 kg of N/ha (9.75 qt/ha), while the lowest seed yield (3.71 qt/ha) was obtained with both nil-received plots of the two fertilizers. The partial budget analysis revealed that the application of 100 kg ha of blended NPSB and 46 kg N/ha resulted in net benefits of 122,425 ETB/ha with an acceptable 2148.478.00% marginal rate of return. Therefore, the application of 100 kg blended NPSB with 46 kg N/ha (64.9 kg N + 37.7 kg P2O5 + 6.95 kg S + 0.1 kg B/ha) fertilizer rates led to optimum black cumin seed yield production and economic returns and was recommended for black cumin growers in the midland areas of the Guji zone.
Keywords: NPSB fertilizer; Seed yield; Silingo; Partial budget analysis
Introduction
Black Cumin (Nigella sativa L.) originated in Egypt and East Mediterranean, but is widely cultivated in Iran, Japan, China, and Turkey [61]. Hence, Black cumin is confirming to be a medicinal plant rich in phytochemicals [70]. In Ethiopia, It is mainly cultivated in Amhara, Oromia, Tigray and SNNPRS and other various places, for household consumption (Habtewold et al., 2007). Nigella sativa is widely cultivated in the Amhara Region, Northern Gondar, and Oromia. It is highly cultivated in Kaffa and Keficho Zones and districts of the Southern Nations, Nationalities People’s Region [37]. It is also particularly growing in Western Arsi (Kofele and Dodola districts) and Arsi Zone (Shirka, Tena and Silitana districts).
Black cumin is commonly used in Amharic "Berbere" in which it tends to reduce its hotness [46], for preparation of curries, bread, katikala [49]," to induce an abortion [48]. Besides its medicinal importance, Black cumin seed is also used for the production of soap, perfumes and lotions, food flavorings, food preservation, nutraceuticals and cosmeceuticals from the Black cumin oil [32].
In Ethiopia, black cumin is one of the most important spice types which are mainly produced to favor foods, preparation of oil for perfumes and medicinal purpose, source of income, crop diversification, and export purposes [30,69]. It is also used for reducing the hotness of pepper powder in the country [36]. The demand for black cumin seed and its oil has also been increasing both in Ethiopian local and national markets for consumption purpose. It is also the second most important cash crop that is exported to the international market next to ginger [69]. Currently, a great deal of attention has been given to the seed and oil-yields of black cumin. Their consumption is increasing [63].
According to Inga and Sebsebe (2000), Nigella sativa is found in an altitudinal range between 1500-2500m. A rainfall of 120-400mm during its growing season could be enough for its optimum production. It grows in temperature ranges of 5-25OC, with 12-14OC being the optimum. Although it is known to be a low water demanding plant typical of semi-arid areas, the availability of water supply over the growing season is very crucial to the timeliness of flower emergence and seed setting. It grows best on well drained sandy loam to loamy soils with a pH range of 6.8 to 8.3. Acidic soils and alkaline soil reduce yield [75]. The sloppy soils of heavy rainfall areas and leveled and well drained soils of moderate rainfall areas are quite suitable for its cultivation. Soil pH of 7.0 to 7.5 is favorable for its production [57,75].
Ethiopia has favorable environmental condition for black cumin production but the national average productivity of black cumin was 0.79 tonnes/ha [45]. Black cumin cropping system has been given a little attention to improve its production and productivity of the crop. Several problems including lack of improved seed, recommended fertilizer rate, lack of knowhow on postharvest handling; improved agriculture practices and extension system, marketing system, etc. are accountable for the continued low productivity and production of black cumin [77].
Adequate use of chemical fertilizer improves the yield and quality of aromatic plants. The appropriate use of fertilizers increases the growth and quality of medicinal plants [54]. Nitrogen nutrient has the largest effect on plant physiology and is probably the single most important limiting nutrient for crop growth [56]. The Availability of nitrogen is of prime importance for growing plants as it is a major and indispensable constituent of protein and nucleic acid molecules [71]. Agricultural soils are often deficient in N and hence, to ensure adequate N supply to crops and to prevent-nutrient deficiencies, large amounts of inorganic N are applied [60]. In phosphorus in the soil has developmental activity in the plant’s root growth. Phosphorus applications, the contact area of the root expands with the growth of the root which, in turn, gives values in the range of 30.7 cm and 35.3 cm in black cumin [42].
Many experiments have been conducted to investigate the effect of different amounts of nitrogen [31,73] and phosphate [52] fertilizers on different agronomic characteristics, yield and yield components of black cumin. According to Rana et al. (2012), the maximum values of agronomic characteristic such as plant height and number of branches and the highest yield of seed were observed at a ratio of 60:120 kg NP ha-1. According to Ebrie et al. (2015) they reported that combination of 45/40 kg NP ha-1 for black cumin production in Konta district. Tuncturk et al. (2012) also reported that 60 kg N ha-1 produce the highest seed yield in Turkey.
Despite its importance, little attention has been given to improving its production and productivity of the crop. Developing and using an improved variety alone is not enough to realize optimum production of the crop unless fertilizers are properly supplied [68]. Moreover, today there is little available information pertaining to agronomic practices including the optimum dose of blended NPSB and nitrogen fertilizers. Applying at a rate to match crop requirement at an economic and sustainable level is therefore desirable. This requires knowledge of the specific crop requirement in a given environments and of the amount being applied. The farmer needs to adjust these rates according to yield potential affected by soil, crop history and variety and anticipated weather.
Even though much of at Adola district has a potential for black cumin production, almost no research work has so far been conducted to determine the rates of blended NPSB and nitrogen fertilizers. Fertilization rates are insufficient to sustain high yields and to replenish nutrient removal by the crop [47]. Black cumin of different genotypes requires a good combination of fertilizers for optimum growth and yield [29]. Since soil test based and site specific nutrient management has been a major tool for increasing the productivity of agricultural soils. According to the Ethio-SIS studies, the soils of the experimental areas are deficient in nitrogen, phosphorous, and sulfur nutrients [38], but the levels of applications were not identified, and there was no information about recommended rates for blended NPSB and N fertilizer application in the study area. Therefore, this research was conducted and answers the farmers question with the objectives of determining optimum rates of blended NPSB and nitrogen fertilizer rates and assessing the cost and benefit of blended NPSB and nitrogen fertilizer rates for Black cumin production in the study areas.
Materials and Methods
Description of the Experimental Site
The experiment was conducted in the midland (Adola district) areas of Guji Zone at one location during the 2021 and 2022 cropping seasons. Adola district is located at about 470 to the south of Addis Ababa. Adola district is characterized by three agro-climatic zones, namely Dega (high land), Weina-dega (mid land), and Kola (low land) with different coverage. The mean annual rain falls and temperature of the district is are about 900mm and 12-34 0c respectively. Based on this condition two-time cropping season was commonly practiced i.e. Arfasa (main cropping season) which starts from March to April especially for maize, haricot bean, sweet potato and Irish potato. The second cropping season is called Gena (short cropping season) which was practiced as double cropping using small-size cereal crops like tef, potato, Pepper, and barley after harvesting the main cropping season crops. This study was also conducted during the short cropping season in midland areas of Guji zone.
Experimental Materials
An improved Black cumin variety called ‘Silingo’ which was released by Kulumsa Agricultural Research Center (KARC) in 2017 [53], was used as a planting material. The variety was selected on the based on its high yield, and wider adaptation in the midlands of Guji Zone. Blended NPSB ((18.9% N, 37.7% P2O5, 6.95% S and 0.1% B) and Urea (CO [NH2]2) (46% N) were used as a source of nitrogen, phosphorus, Sulfur, and Boron respectively.
Treatments and Experimental Design
The treatments consisted of four levels of NPSB (0, 50, 100, and 150 kg NPSB ha-1) and four levels of nitrogen (0, 23, 46, and 69 kg N ha-1) fertilizer rates
The experiment was laid out as a Randomized Complete Block Design (RCBD) in a factorial arrangement and replicated three times per treatment. There are 16 treatment combinations, which were assigned to each plot randomly. The total number of plots was 48 and each plot was 2.4m in length and 2.4m in width = 5.76 m2 in size consisting of six rows, 0.40 m between rows. While the net harvested area is 2.4m (4 rows × 0.4 m) =3.84m2 (the four central rows). The spacing between plots and adjacent blocks was 0.5 m and 0.75m, respectively. Urea was applied in the split. All pertinent management practices were carried out following the recommendation of the crop.
Soil Sampling and Analysis
The composite soil samples were collected by using Auger (Soil sampler) from 0-20 cm depth based on the procedure outlined by Taye (2000) and using the zigzag method [33]. The surface soil samples collected from the experimental field were air dried and grinded and allowed to pass through a 2mm sieve and for further analysis for total nitrogen and organic carbon were allowed to pass through a 0.5 mm sieve [40]. Pre-planting soil samples were analyzed for particle size distribution (soil texture), soil pH, Cation Exchange Capacity (CEC) (Meq/100g soil), organic carbon (%), available potassium (ppm), phosphorus (ppm), and available sulfur (ppm), boron(ppm), total nitrogen (%), exchangeable magnesium, sodium, and calcium (Cmol (+) kg-1) at Horti coop Ethiopia soil and water analysis laboratory.
Data collection
Phenology, Growth, yield and yield components were collected:- Days to 50% flowering, Days to 90% maturity, Plant height (cm), Number of branches per plant), Number of capsules per plant, Number of seeds per capsule, Seed yield (qt ha-1)
Partial Budget Analysis
The partial economic analysis was carried out by using the methodology described in CIMMYT (1988). Only the cost that varied among different treatments was taken into account. The yield of the crop was adjusted downward by 10% to reflect the difference between the experimental yield and the yield farmers expect from the same treatments. The treatment which gives the highest NB and a MRR greater than the minimum is considered acceptable to farmers (>1 or 100%). To compare the costs that varied with the net benefits, the marginal rate of return was calculated as NB = TR – TVC
Data Analysis
Field data were analyzed by using SAS software for the data following the standard procedures outlined by Gomez and Gomez (1984). Comparisons among the treatment means were done using Duncan's Multiple Range Test (DMRT) tests at 0.05 level of significant.
Results and Discussion
Physico-Chemical Soil Properties of the Experimental Site
The laboratory results of the selected physico-chemical properties of the soil sample taken pre-planting and post-harvesting are presented in Table 3. The results of pre-planting indicate that the soil has 32, 24, and 44% sand, silt, and clay, respectively, as well as post-harvesting soil having 30, 22, and 48% sand, silt, and clay, respectively, and could be categorized as clay soil on the basis of the 1987 USDA textural soil classification system. According to Murphy (2007), the experimental soil has medium CEC (23.79 and 24.13 meq/100g soil) pre-planting and post-harvest, respectively. The rating made by FAO (2006) indicates that the contents of exchangeable potassium are high (1.10 and 0.71 Cmol (+) kg-1soil), exchangeable Mg is high (3.48 and 2.87 Cmol (+) kg-1soil), exchangeable Ca is high (15.53 and 13.71 Cmol (+)) kg-1soil), and exchangeable Na is low to very low (0.11 and 0.07 Cmol (+) kg-1soil) pre-planting and post-harvesting, respectively. According to the rating of Tekalign (1991), the organic carbon (OC) content of 1.68 and 3.36 percent could be categorized as low to medium pre-planting and post-harvesting, respectively.
B
0
0
0
0
0.05
50
18.85
0.05
50
18.85
0.05
50
18.85
0.05
0.1
41.9
37.7
6.95
0.1
64.9
37.7
6.95
0.1
87.9
37.7
6.95
0.1
0.15
150
56.55
10.425
0.15
150
56.55
10.425
0.15
150
56.55
10.425
0.15
Table 1: List of experimental treatments, fertilizer compositions and their descriptions.
Pre planting
Physical and Chemical Property
Value
Rating
Reference
Sand
32%
-
-
Clay
44%
-
-
Silt
24%
-
-
Textural class
Clay
-
USDA ,1987
pH (1: 2.5 soil H2O ratio)
5.97
moderately Acidic
EthioSIS, 2014
Organic matter (%)
2.89
low
EthioSIS, 2014
Organic carbon (%)
1.68
low
Tekalign, 1991
Total N (%)
0.29
medium
EthioSIS, 2014
CEC (meq/100 g soil)
23.79
medium
Murphy, 2007
Available P (ppm)
9.20
low
EthioSIS, 2014
Available S (ppm)
14.08
low
EthioSIS, 2014
Available B (ppm)
0.97
low
EthioSIS, 2014
Ex. K [Cmol(+)kg-1soil]
1.10
high
FAO, 2006
Ex.Mg [Cmol(+)kg-1soil]
3.48
high
FAO, 2006
Ex.Ca [Cmol(+)kg-1soil]
15.53
high
FAO, 2006
Ex.Na [Cmol(+)kg-1soil]
0.11
low
FAO, 2006
Post harvesting
Sand
30%
-
-
Clay
48%
-
-
Silt
22%
-
-
Textural class
Clay
-
USDA, 1987
pH (1: 2.5 soil H2O ratio)
6.07
moderately Acidic
EthioSIS, 2014
Organic matter (%)
5.79
Medium
EthioSIS, 2014
Organic carbon (%)
3.36
high
Tekalign, 1991
Total N (%)
0.28
medium
EthioSIS, 2014
CEC (meq/100 g soil)
24.13
medium
Murphy, 2007
Available P (ppm)
7.21
low
EthioSIS, 2014
Available S (ppm)
10.52
low
EthioSIS, 2014
Available B (ppm)
0.81
low
EthioSIS, 2014
Ex. K [Cmol(+)kg-1soil]
0.71
high
FAO, 2006
Ex.Mg [Cmol(+)kg-1soil]
2.87
medium
FAO, 2006
Ex.Ca [Cmol(+)kg-1soil]
13.71
high
FAO, 2006
Ex.Na [Cmol(+)kg-1soil]
0.07
very low
FAO, 2006
Table 2: Physical and chemical properties of pre-planting and post-harvesting at Adola Kiltu Sorsa on the farm during 2021 and 22 main cropping season.
Source of Variables
Parameters
DF
DM
PH(cm)
NCPP
NSPC
Syld qt/ha
Rep.
5.32Ns
72.80Ns
49.68*
2.51Ns
122.99Ns
6.91*
Year
32.66**
600.00**
27.22Ns
4.86Ns
1565.58*
942.32***
NPSB
35.66***
48.26Ns
46.04*
7.59*
853.05*
12.45***
N
37.55***
78.82*
38.91*
20.38***
387.94Ns
11.27***
NPSB*Year
14.11*
Ns
11.9Ns
Ns
400.83Ns
3.11Ns
N*Year
6.67Ns
Ns
5.63Ns
Ns
95.66Ns
9.45*
NPSB*N
3.88**
162.15***
53.13*
4.06*
189.75Ns
7.28***
NPSB*N*Year
6.78*
Ns
20.53Ns
Ns
59.19Ns
3.16*
Significant‘***’ 0.001, ‘**’ 0.01, ‘*’ 0.05 and Non-Significant (NS) at P>0.05.DF= Days to 50% Flowering, DM= Days to 90% Maturity, PH= Plant height(cm),NCPP= No. capsule per plant, NSPC=No. of Seed per capsule, and Syld= Seed yield qt/ha
Table 3: Mean squares of ANOVA for Black Cumin Phenology, growth, yield and yield component effects of blended NPSB and N fertilizer rates at Adola, Southern Ethiopia in 2021 and 2022 growing season.
Furthermore, according to EthioSIS (2014), the soil of the experimental site is moderately acidic in reaction (pH of 5.97 and 6.08), medium in total N (0.29 and 28%), low in available S (14.08 and 10.52 ppm), low in available B (0.97 and 0.81 ppm), and low in available phosphorus (9.20 and 7.21 ppm) pre-planting and post-harvest, respectively. At increased soil acidity (pH reduces value), phosphorus is fixed to surfaces of Fe and Al oxides and hydrous oxide, which are not readily available to plants [62]. Black cumin can grow in well-drained sandy loam to loamy soils with a pH range of 6.8 to 8.3 [48]. However, the low content of available phosphorus, sulfur, and organic matter calls for the application of mineral and/or organic fertilizers containing these nutrients.
Mean Squares of Black Cumin Parameters
The overall year's analysis of variance showed that the interaction effect of blended NPSB and nitrogen fertilizers significant difference (P<0.05) were observed on days to 50% flowering, days to 90% physiological maturity, plant height, number of capsules per plant, and seed yield (Table 3). However, the non-significant differences at (P>0.05) was observed among their interaction of blended NPSB and nitrogen fertilizers on the number of seeds per capsule (Table 3). Moreover, overall years analysis of variance showed that the interaction effect of blended NPSB, nitrogen, and years showed statistically significant differences (P<0.05) observed on days to 50% flowering, and seed yield. However, non-significant differences at (P>0.05) were observed among their interaction of blended NPSB, nitrogen, and years on days to 50% flowering, plant height, number of capsules, and number of seeds per capsule (Table 3).
Days to 50% Flowering
Increasing the application rate of NPSB/N 150/69 kg ha-1 prolonged the time required to attain 50% flowering (73.67 days). The earliest days to reach 50% flowering (67.5 days) were observed from nil-treated plots of NPSB and nitrogen (Table 4). This is due to excessive nitrogen and phosphorous, which result in prolonged vegetative growth of the plant. This result is in agreement with the findings of Ozguven and Sekeroglu (2007).
NPSB Rates (kg ha-1)
Days to 50% flowering
Days to 90% physiological maturity
Nitrogen (kg ha-1)
Nitrogen rates (kg ha-1)
0
23
46
69
0
23
46
69
0
67.5d
67.67d
69cd
70cd
114.2de
117.5b-e
115.8cde
115.8cde
50
67.67d
69.33cd
69.67cd
70.67c
117.5b-e
125.8a
114.2de
115.8cde
100
68.67cd
69.33cd
69.33cd
70cd
122.5abc
114.2de
114.2de
125.8a
150
69.17cd
69.83cd
73ab
73.67a
114.2de
112.5e
114.2de
124.2ab
Mean = 69.66
Mean = 117.8
LSD (0.05) = 0.9
LSD (0.05) =3.06
CV (%) = 2.4
CV (%) = 4.5
Table 4: Over year Pooled mean interaction effects of NPSB and N fertilizer rates on days to 50% flowering and days to 90% physiological maturity of black cumin.
NPSB Rates (kg ha-1)
Plant height(cm)
Number of capsules per plant
Nitrogen (kg ha-1)
Nitrogen rates (kg ha-1)
0
23
46
69
0
23
46
69
0
31.11e-i
36.62a-d
30.32f-i
31.97d-i
5.17cde
5.5b-e
4.38de
6.44bc
50
33.90b-h
32.64c-i
36.51a-d
39.48a
4.05e
6.55bc
7.11ab
8.55a
100
34.49b-f
29.90gi
37.08abc
35.22a-e
4.33e
5.39cde
6.11bcd
6.44bc
150
36.35a-d
29.24gi
35.61a-e
37.61ab
5.11cd
4.99cde
5.33cde
6.22bc
Mean =34.5
Mean = 5.73
LSD (0.05) = 1.98
LSD (0.05) = 0.83
CV (%) = 9.99
CV (%) = 24.9
Table 5: Over location and year Pooled mean interaction effects of NPSB and N fertilizer rates on plant height and Number of capsules per plant of black cumin.
Treatments
Yield related parameter
NPSB rate (kg ha-1)
Number of seed per capsule
0
51.39b
50
65.82a
100
60.07ab
150
57.92ab
Nitrogen rate (kg ha-1)
0
53.04
23
62.1
46
59.21
69
60.84
Mean = 58.8
LSD (5%) = 17.58
CV (%) = 26
Table 6: Over year Pooled mean main effects of NPSB and N fertilizer rates on the number of seeds per capsule of black cumin.
Days to 90% Physiological Maturity
Late maturing (125.8 days) was observed from the application of 50 and 100 kg NPSB and 23 kg N ha-1, while early maturing (112.5 days) was observed from 150 and 23 kg NPSB/N per hectare. The delay in days to physiological maturity from increased application of NPSB and nitrogen might be enhancing vegetative growth rather than physiological maturity. This result agrees with the findings of Kar et al. (2012) who reported that nitrogen fertilizer has significantly affected the days to 90% physiological maturity of black cumin. This suggestion is also in agreement with that of Tantowijoyo and Van de Fliert (2006) that the application of nitrogen fertilizer at higher rates enhances vegetative growth by helping the plant absorb sunlight and produce carbohydrates but delays the production of reproductive parts and thereby maturity.
Plant Height
The tallest plant height (39.48cm) was obtained from the application of 50 kg NPSB ha-1 and 69 kg N ha-1. The shortest plant height (29.24cm) was obtained from the application of 150 kg NPSB ha-1 and 23 kg N ha-1. Plant heights might be controlled genetically and/or by environmental factors. The reason may be due to higher doses of nitrogen applied which itself increases plant growth by promoting processes such as cell division, cell enlargement, and metabolic processes. Nitrogen and phosphorus enhance the vegetative growth of plants by increasing cell division, elongation, and varietal variability to absorb the nutrients from the soil [63].
Number of Capsules per Plants
The highest number of capsules per plant (8.55) was obtained from the combination of 50 kg NPSB ha-1 and 69 kg nitrogen ha-1, while the lowest (4.05) was obtained from 50 kg NPSB ha-1 and the unfertilized treatment nitrogen. This could be the conducive environment of chemical and physical properties of the soil, support for soil microorganisms, as well as increased availability of nitrogen and phosphorous. The main factor for better plant height is an increased number of primary, secondary, and tertiary branches. There could be a possibility of increasing the number of fruit-producing buds, which are the locations for capsule formation. Increased application of nutrients might result in more vigorous plant growth with greater plant height, number of branches, number of leaves, and number of capsules, producing a greater total plant biomass, thereby resulting in a higher biological yield [29].
In addition, an adequate supply of nitrogen is associated with vigorous vegetative growth and more efficient use of other nutrients. Rana et al. (2012) and Tuncturk et al. (2012) also reported an increased capsule number per plant of black cumin with increased fertilizer levels. This result is also in agreement with the findings of Ozguven and Sekeroglu (2007).
Number of Seeds Per Capsule
The highest number of seeds per capsule (65.82) was obtained at the application of 50 kg of NPSB per hectare, while the lowest (51.39) was obtained from the unfertilized treatment. The highest number of seeds per capsule (62) was obtained at the application of 23 kg N ha-1, while the lowest (53.04) was obtained from the unfertilized treatment, which is statistically the same but numerically different.
Seed Yield
The highest seed yield (9.75qtha-1) was recorded with the combined application of 100 kg NPSB ha-1 and 46 kg N ha-1, while the lowest yield (3.71qtha-1) was recorded from the control treatment (Table 7). Similar results concerning the positive response of the nigella crop to inorganic fertilization were also recorded by another researcher, Yiman et al. (2015). Valabadi and Aliabadi (2011) found yields of up to 1.43 t/ha. Tuncturk et al. (2012) reported that increasing phosphorus doses positively influenced seed yields in black cumin. Moreover, the agronomic parameters contributed directly or indirectly to the total seed yield for black cumin. This result is in agreement with the findings of Girma et al. (2016) and Fufa (2016) who reported black cumin seed yield is positively correlated with plant height, number of capsules per plant, number of primary branches per plant, and number of seeds per capsule. Moreover, in agreement results with that of Tuncturk et al. (2012) who reported that increasing phosphorus doses positively influenced seed yields in black cumin.
NPSB Rates (kg ha-1)
Seed Yield(qt/ha)
Nitrogen (kg ha-1)
0
23
46
69
0
3.71b
7.41ab
5.78ab
7.05ab
50
6.37ab
7.27ab
7.55ab
7.59ab
100
7.14ab
7.68ab
9.75a
6.26ab
150
6.37ab
7.28ab
7.23ab
6.34ab
Mean = 6.96
LSD (0.05) = 0.68
CV (%) = 17.16
Table 7: Over year Pooled mean interaction effects of NPSB and N fertilizer rates on Seed yield of black cumin.
Correlation Analysis
The correlation analysis was performed to determine simple correlation coefficient between Phenology, growth, yield and yield component parameters as affected by NPSB and Nitrogen fertilizers application. The present finding has indicated that the number of capsules per pod was positively correlated with plant height (r=0.304). Seed yield was significantly and positively correlated with Days to maturity (r=0.399), and Number of seeds per capsule (r=399). Seed yield was inversely (negatively correlated) related with days to 50% flowering (r=-0.137) (Table 8). Correlation coefficients close to +1 or –1 indicate a close fit to a straight line (strong correlation) and values closer to zero indicate a very poor fit to a straight line or no correlation. According to [66] correlation coefficient analysis attempts to measure the strength of relationships between two variables using of a single number.
Characters/Traits
Characters/Traits
DF
DM
PH
NCPP
NSPC
SYLD
DF
1
DM
0.116
1
PH
0.24
0.134
1
NCPP
0.177
0.079
0.304
1
NSPC
0.113
0.129
0.263
0.23
1
SYLD
-0.137
0.311
0.049
0.194
0.399
1
Table 8: Correlation analysis on phenology, growth, yield, yield components Characters/traits of Black Cumin at Adola on-farm in 2021 and 2022 cropping season.
Partial Budget Analysis
The results of the study indicated that blended NPSB and N fertilizers had a greater promotion benefit than the control. Partial budget analysis was done based on the view of the CIMMYT Economics Program (1988) recommendations, which stated that the application of fertilizer with a marginal rate of return above the minimum level (100%) is economical. As a result of this study, partial budget analysis revealed that the maximum net benefit of 122,425 ETB with an acceptable Marginal Rate of Return (MRR) of 2148.478.00% was recorded in the treatment that received the application of 100 kg blended NPSB ha-1 and 46 kg N ha-1 fertilizer rates, respectively (Table 9). However, the lowest net benefits of Birr 50085 ha-1 and non-acceptable Marginal Rates of Return (MRR) were obtained in both nil-received plots of blended NPSB and N fertilizers, respectively. The application of 100 kg of blended NPSB ha-1 and 46 kg of N ha-1 generated 122,425 ETB ha-1 more compared to both nil-received plots of blended NPSB and N fertilizers, respectively. The application of 100/46 kg blended NPSB and N per hectare gives the highest net benefit and a marginal rate of return greater than the minimum considered acceptable to farmers (>1 or 100%).
Treatments
Un Adjusted Seed Yield (kgha-1)
Adjusted Seed yield (kgha-1)
Total variable cost (ETB)
Total
Revenue (ETB)Net
benefit (ETB)MRR%
NPSB rate
(kg ha-1)Nitrogen rate
(kg ha-1)0
0
371
333.9
0
50085
50085
-
0
23
741
666.9
2300
100035
97735
D
50
0
637
573.3
2300
85995
83695
D
0
46
578
520.2
4600
78030
73430
D
50
23
727
654.3
4600
98145
93545
D
100
0
714
642.6
4600
96390
91790
D
0
69
705
634.5
6900
95175
88275
D
100
23
768
691.2
6900
103680
96780
D
150
0
637
573.3
6900
85995
79095
D
50
46
755
679.5
6900
101925
95025
692.61
50
69
759
683.1
9200
102465
93265
D
150
23
728
655.2
9200
98280
89080
D
100
46
975
877.5
9200
131625
122425
2148.478
100
69
626
563.4
11500
84510
73010
D
150
46
723
650.7
11500
97605
86105
622.39
150
69
634
570.6
13800
85590
71790
D
Where, blended NPSB cost = Birr 20 kg-1of blended NPB, N cost = Birr 20 kg-1, blended NPSB and N fertilizers application cost=Birr 6 kg-1 of blended NPSB and N, Application cost of blended NPSB and N fertilizers 6 persons 100 kg ha-1, each 75 ETB day-1, Field price of black cumin during harvesting= Birr 150 birr kg-1, MRR (%) = Marginal rate of return and D= Dominated treatment.
Table 9: Partial budgets and marginal rate of return analysis effect of blended NPSB and Nitrogen fertilizer rates to Black cumin variety at Adola on-farm in 2021 and 2022 cropping season.
Conclusions and Recommendations
Black cumin is one of the most important food security and cash crops for farmers in mid-land parts of southern Ethiopia, particularly in the Guji zone. Nowadays, black seed plays a vital role throughout the world because of its importance in health, pharmaceuticals, spices, and income-earning. Even though black cumin is important, the production and productivity obtained from the hectares are very low compared to other countries. The main reasons for the lower productivity are mainly attributed to a lack of improved variety, a lack of fertilizer management, a lack of knowledge of cultural practices, and insect pest management.
The overall year’s analysis of variance showed that the interaction effect of blended NPSB, nitrogen, and years showed statistically significant differences were observed on days to 50% flowering and seed yield. However, non-significant differences were observed among their interactions of blended NPSB, nitrogen, and years on days to 50% flowering, plant height, number of capsules, and number of seeds per capsule. The highest seed yields were obtained with the application of 100 kg of blended NPSB/ha and 46 kg of N/ha (9.75 qt/ha), while the lowest seed yields (3.71 qt/ha) were obtained with both nil-received plots of the two fertilizers.
The partial budget analysis revealed that the application of 100 kg/ha blended NPSB and 46 kg/ha resulted in net benefits of 122,425 ETB/ha with an acceptable 2148.478.00% marginal rate of return. Therefore, combined application of 100 kg NPSB with 46 kg N ha-1 (64.9 kg N+37.7 kg P2O5+6.95 kg S+0.1 kg B/ha) produces the highest seed yield, is economically feasible, and is recommended for black cumin growers in the midland areas of the Guji zone.
Author Statements
Acknowledgment
I would like to acknowledge the Oromia Agricultural Institute and Kulumsa Agricultural Research Center for providing all the necessary financing, facilities, and support during the entire experimentation and for providing me with planting materials for black cumin. I would also like to extend my heartfelt appreciation to Bore Agricultural Research Center for providing me with moral support, vehicles, and stationery and for their assistance during site selection, preparation of inputs, and data collection for the research.
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