Despite the fact that mineral fertilizers are widely considered as a major option for addressing the crisis of nutrient depletion, their use among smallholder farmers is not adequate due to an escalating cost. Alternatively, nutrient-rich organic sources that are easily available to farmers are not widely promoted. Thus, this study was carried out in the research field of Wolaita Sodo University, Southern Ethiopia, to evaluate the effects of locally available organic nutrient sources and nitrogen (N) phosphorus (P) sulfur (S) fertilizer (19N-46P2O5-7S) on the productivity and economic performance of common bean. The organic materials used were
Agriculture, a soil-based industry, is supporting the livelihood for over 80% of the Ethiopian population that is estimated 114 million in 2020 [
Emerging research outcomes from various parts of Ethiopia demonstrated alarmingly low soil organic matter (SOM) and deficiencies of essential nutrients such as nitrogen (N), phosphorus (P), potassium (K), sulfur (S), boron (B), and copper (Cu) as the main causes of crop yield decline and nonsustainable agricultural production [
Mineral fertilizers are widely considered as a major option for addressing the crisis of nutrient depletion and sustaining food production. In Ethiopia, application of inorganic fertilizer containing N and P in the form of urea (46N-0-0) and diammonium phosphate (DAP) (18N-46P2O5) has long been started some 50 years ago after realizing that both nutrients are a widespread problem. However, crop yield gain from both fertilizers is gradually declining over time despite steady increases in fertilizer consumption in the country [
The use of organic nutrient sources derived either from livestock or plants has been receiving worldwide support as they are the store house and source of several essential plant nutrients [
According to Alhrout et al. [
The study was carried out in 2017 at the Wolaita Sodo University (WSU) research and practical farm in Sodo Zuria district, Southern Ethiopia. Geographically, it is located in 06°50′00″N latitude and 37°45′07″E longitude with an altitude of 1882 m above the mean sea level. The annual average rainfall was 1212 mm and characterized by having a bimodal rainfall pattern that forms two cropping seasons, namely,
Nitisol is the dominant soil type which occurs in the experimental location and district. The site has clay textural class. In terms of chemical properties, the experimental site had slightly acidic reaction (pH = 5.9) with low content of organic carbon (OC) (0.17%), total nitrogen (0.01), and available P (5.4 mg/kg) [
A factorial experiment consisting of three levels of organic fertilizer (0, 2.5 and 5 t·ha−1) and four levels of NPS fertilizer (0, 50, 100 and 150 kg·ha−1) was arranged in a Randomized Complete Block Design (RCBD) with three replications. Nutrients from organic sources were obtained from two agroforestry tree leaves, namely,
Two seeds per hill were planted in rows 40 cm apart and, with 10 cm between seeds. A distance of 0.5 m × 1 m was left between plots and blocks, respectively. Thinning was performed after full emergence of the crop by leaving one seedling per hill. Each plot had six rows and a total of 60 plants per plot. Weeding and other necessary agronomic management practices were carried out properly. These procedures were repeated on each of crop-growing seasons.
Organic materials collected from the tree leaves were chopped, dried in shade, and then, oven dried at 70°C until constant weight. The leave litters were ground and used for characterization of chemical composition. The chemical composition, namely, N, P, K, and OC, and C : N contents of organic materials were determined according to the work of Sahlemedhin and Taye [
Data on the plant height, leaf area index (LAI), and dry matter per plant were recorded from five randomly selected plants of internal rows. The plant height was measured from the base of the plant to the apical bud of plant and expressed in centimeters. The leaf area index (LAI) was calculated as the ratio of total leaf area to ground area occupied by the plant using a pictorial method [
Yield components, namely, numbers of branches per plant, numbers of pods per plant, and numbers of seeds per pods, and 1000 seeds weights were also recorded from randomly selected five plants at two central rows of the plot. Grain yield was collected on a plot bases and after 10% moisture adjustment, it was converted to ton/ha.
The partial budget analysis was carried out using the methodology described in CIMMYT [
All data obtained from experiments were subjected to analysis of variance (ANOVA) using SAS [
The chemical composition of
Chemical characteristics of organic nutrient sources.
Leave litters | OC | N | P | K | C : N |
---|---|---|---|---|---|
% | % | mg/kg | % | - | |
50.83 | 5.2 | 11.07 | 3.07 | 10 | |
51.83 | 4.7 | 18.59 | 2.12 | 11 |
The plant height of haricot bean plants was significantly (
Plant height, branches per plant, and seeds per pods affected by NPS and organic fertilizer.
Plant height (cm) | Branch plant−1 (No.) | Seed pod−1 (No.) | |
---|---|---|---|
NPS (kg/ha) | |||
0 | 57.972d | 3.4444d | 2.8622c |
50 | 69.906c | 4.4778c | 4.0889b |
100 | 77.339b | 4.9889b | 4.5478a |
150 | 85.856a | 5.6778a | 4.9033a |
LSD0.05 | |||
OF (t/ha) | |||
0 | 64.279b | 4.0167b | 3.6075c |
2.5 | 75.050a | 4.8250a | 4.1192 b |
5 | 78.975a | 5.100a | 4.5750a |
LSD0.05 | |||
CV (%) |
The leaf area index (LAI) of haricot bean was significantly influenced by the combined effects of NPS and OF application (Table
LAI, pods per plant, 1000 seed weight, biomass per plant, and grain yields of haricot bean affected by organic and NPS fertilizer.
LR | LAI | Pods per plant (PPPL) | 1000 seeds wt. | Dry matter plant−1 | Grain yield (ton/ha) | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0 t/ha | 2.5 t/ha | 5 t/ha | 0 t/ha | 2.5 t/ha | 5 t/ha | 0 t/ha | 2.5 t/ha | 5 t/ha | 0 t/ha | 2.5 t/ha | 5 t/ha | 0 t/ha | 2.5 t/ha | 5 t/ha | |
NPS (kg/ha) | |||||||||||||||
1.35d | 2.41c | 3.59b | 7.8 g | 14.7f | 19.9cde | 198.5b | 246.5a | 248.0a | 12.2 g | 27.9ef | 29.6ef | 1.01 g | 2.32f | 3.17de | |
2.54c | 3.61b | 3.96ab | 17.0ef | 19.2de | 21.6bcd | 235.3a | 238.5a | 234.9a | 25.9f | 32.6cde | 37.8bc | 2.08f | 3.18de | 3.27cde | |
4.01ab | 4.39a | 3.94ab | 21.7bcd | 22.3bcd | 23.0abc | 235.0a | 241.1a | 247.9a | 31.6def | 32.6cde | 40.1ab | 3.10e | 3.81abc | 3.43bcde | |
4.35a | 4.23ab | 4.49a | 23.2 ab | 25.5a | 24.1ab | 238.9a | 241.9a | 245.1a | 36.6bcd | 36.4bcd | 45.2a | 3.73abcd | 4.16a | 3.93ab | |
Leaf area index of haricot bean as affected by interaction effects of NPS and organic fertilizer.
In our study, a faster daily decay rate (
The number of branches per plant and seeds per pod were significantly (
Integrated application of 150 kg NPS/ha + 2.5 t/ha OF significantly enhanced the pod number per plant by 227% over unfertilized plots (Figure
Number of pods/plant of haricot bean as affected by interaction effects of NPS and organic fertilizer.
Pearson correlation matrix of applied fertilizers and agronomic parameters.
NPS | OF | LA | LAI | PHT | BPL | PODPT | SEDPOD | TSW | BIOMP | |
---|---|---|---|---|---|---|---|---|---|---|
LA | 0.768 | 0.434 | ||||||||
LAI | 0.730 | 0.384 | 0.862 | |||||||
PHT | 0.735 | 0.433 | 0.845 | 0.834 | ||||||
BPL | 0.753 | 0.412 | 0.835 | 0.803 | 0.843 | |||||
PODPT | 0.727 | 0.375 | 0.801 | 0.863 | 0.834 | 0.744 | ||||
SEDPOD | 0.779 | 0.418 | 0.836 | 0.808 | 0.810 | 0.850 | 0.758 | |||
TSW | 0.274 | 0.448 | 0.556 | 0.565 | 0.564 | 0.442 | 0.695 | 0.382 | ||
BIOMP | 0.639 | 0.528 | 0.804 | 0.777 | 0.836 | 0.836 | 0.800 | 0.861 | 0.584 | |
GY | 0.696 | 0.414 | 0.834 | 0.862 | 0.765 | 0.705 | 0.873 | 0.642 | 0.638 | 0.626 |
The results regarding yield attributes are in accordance with the findings of Zahida et al. [
Interactive effects of NPS and OF significantly (
Data regarding grain yield indicated that application of 150 kg NPS/ha and 2.5 t·OF/ha significantly resulted the highest grain yield (4.16 t/ha) which was a 312% increase over unfertilized crop (1.01 t/ha) (Figure
Grain yield of haricot bean as affected by interaction effects of NPS and organic fertilizer.
The result revealed that the application of 150 kg·NPS/ha + 2.5 t·OF/ha recorded the highest net benefit (27179.5 birr) with acceptable MRR (>100%) (Figure
Net return of haricot bean as affected by interaction effects of NPS and organic fertilizer.
Profitability as affected by NPS and OF fertilizer rates.
OF (tha−1) | NPS (kg·ha−1) | GY (tha−1) | Adj.GY (tha−1) | GB (ETB) | TVC (ETB) | Net benefit (ETB) | MRR (%) |
---|---|---|---|---|---|---|---|
1.01 | 0.91 | 7272 | 0.0 | 7272.0 | — | ||
2.08 | 1.87 | 14976 | 757.5 | 14218.5 | 917.0 | ||
3.1 | 2.79 | 22320 | 1515.0 | 20805.0 | 869.5 | ||
3.73 | 3.36 | 26856 | 2272.5 | 24583.5 | 498.8 | ||
2.32 | 2.09 | 16704 | 500.0 | 16204.0 | — | ||
3.18 | 2.86 | 22896 | 1257.5 | 21638.5 | 717.4 | ||
3.81 | 3.43 | 27432 | 2015.0 | 25417.0 | 498.8 | ||
4.16 | 3.74 | 29952 | 2772.5 | 27179.5 | 232.7 | ||
3.17 | 2.85 | 22824 | 1000.0 | 21824.0 | — | ||
3.27 | 2.94 | 23544 | 1757.5 | 21786.5 | D | ||
3.43 | 3.09 | 24696 | 2515.0 | 22181.0 | 52.1 | ||
3.93 | 3.54 | 28296 | 3272.5 | 25023.5 | 375.2 |
Unit cost of NPS = 15.15 ETB/Kg, application cost of organic fertilizer = 20 ETB/Qt = 200 ETB/ton, MRR (%) = marginal rate of return,
This study demonstrated that an integrated application of 150 kg·NPS/ha and 2.5 t·OF/ha resulted in faster decomposition and the highest growth, yield component, and grain yield over unfertilized crop. The effect on grain yield was triple (312%) that of unfertilized crop. Additionally, 31% and 79% yield increment compared with sole OF application at 2.5 t/ha and 5 t/ha, respectively, were recorded. Economic analysis has further confirmed the highest net benefit from the combined application of 150 kg·NPS/ha and 2.5 t·OF/ha. Therefore, under low input cropping systems such as the study area, integrated use of mineral fertilizer with locally available organic nutrient sources are suggested to enhance soil quality and crop productivity. Resource-poor farmers are advised to use sole OF at 5 t/ha as it recorded superior yield and economic advantage over unfertilized to 100 kg·NPS/ha.
The data used to support the findings of this study are available from the corresponding author upon request.
The authors declare that there are no conflicts of interest.
The authors collected, analyzed, interpreted, and prepared the manuscript.
The authors acknowledge the department of Plant Science of WSU for providing experimental land and support in using the laboratory.