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

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.