3.1. Determinants of Yield of Coffee
Respondent characteristics such as gender, educational level, family size, coffee-growing experience, and landholding size are the major factors that influence coffee yield in the study area (Table 3). Most of the respondents (91%) were male-headed households (Table 2). The econometric model analysis result indicated that the sex of the households significantly (P = 0.01) determines the yield of coffee (Table 3). Keeping other factors constant, as the number of male-headed households increased, the coffee yield increased by 0.41%. Because female-headed households have no access to current information, modern technology, access to credit and extension services as that male-headed households. (Gebre et al.,2021; Kangile et al., 2021; Mohammedsani, 2014; Doss and Morris, 2000). They reported that females have less access to improved agricultural technologies and extension services, which contributes to lower adoption rates. Furthermore, male-headed households have better access to information than female households which helps in the adoption of improved agricultural technologies.
About one-third (34% and 27%) of the respondents completed their elementary education (5–8 grade) and were illiterate/uneducated, respectively (Table 2). Education level has shown a positive and significant relationship with the yield of coffee (Table 3). Farmers who are educated (who can read and write) tend to be more efficient in coffee production compared to farmers who are unable to read and write. Education level has a strong and important contributing factor to farmers’ implementation of improved agricultural technologies (Gezahagn, 2019; Deressa et al., 2009; Nchare, 2007; Zemedu, 2004). Consequently, education and any learning or training is a vital factor for the farmers to understand and interpret the information coming from any direction to them. Farmers’ education is also crucial to the effective work of promoting the extension services because if the farmers have a better education, they can have the capability to read and interpret easily the information transferred from the personnel to them. When they are educated enough, they are more competent in the management of the intensive systems of coffee production and marketing. As a result, there is a need frequently to record-keeping on production activities, revenue, and expenses to properly exploit the benefit of the business.
Farmers in the study areas have long years of coffee farming experience (ranges from 5 to 60 years with an average of 21 years) (Table 2). The farming experience of the farmers is also an important determinant that influences the yield of coffee. The experience allows farmers to make better decisions that diminish crop disasters in terms of yield. The result showed that a 1% increase in farm experience leads to an increase in coffee productivity by 0.13% (Table 3). Farming experience over a long period of time aids the farmers to acquire great functional skills in the relationship between inputs and outputs and make good decisions in choosing appropriate input use. Consequently, farmers who have accumulated coffee farming experiences over a long period of time have better chances to intensify their coffee yield. Additionally, the farming experience of the farmers is also an important factor, which allows farmers to make better choices that decrease crop disaster in terms of both quality and quantity. Farmers with longer farming experience are expected to be more knowledgeable and skillful (Gezahagn, 2019; Senkondo et al., 2004).
The study areas have been known as one of the major coffee-producing areas where both small-scale and large-scale coffee plantation exists. The average land-holding capacity of the study areas is high compared to other major coffee-producing districts (like Gomma and Manna districts) in Jimma zone (Diro and Erko, 2019; Diro et al., 2016). The report revealed that the average coffee land holding size of the study area was 2.08 hectares (Table 2). The coffee landholding capacity has a negative relationship with coffee yield. The finding indicated that a 1% increase in coffee farm size tends to decrease coffee yield by 0.009% keeping other variables constant (Table 3). This suggests that excess land allocation for coffee production requires additional distribution of resources which may disgust and discourage farmers. This leads to a decrease in the production efficiency of coffee. The sign of the coefficient concurred with the different findings (Gezahagn, 2019; Mukasa and Salami, 2015; Oseni et al., 2015; Aguilar et al., 2014; Adesoji and Farinde, 2006; Minai et al., 2014; Njuki et al., 2006). However, this study contrasts with the outcomes of Gebre et al. (2021) who stated that an increase in farm size by 1% increases coffee output by 35% Holding all other factors constant /Ceteri paribus.
Most of the coffee trees in the farms were aged trees. The average age of coffee in the the study districts was 20.5 years (Table 2). There is a negative relationship between the age of coffee trees and the yield of coffee (Table 3). When the age of coffee trees increased by 1%, the productivity of coffee will be decreased by 1.05%. this indicates that the habit of keeping aged coffee trees beyond the productive aged is common in the study area. This charges the farmers by declining the yield of coffee.
The average family sizes of the households in the study districts were about 6. Whereas the maximum and minimum family size was 19 and 1, respectively (Table 2). The household family sizes have positive relationships with yield of coffee in the study districts (Table 3). In the study area, when the number of household family sizes increased by 1%, the yield of coffee will increase by 0.008%. The number of family members actively engaged in coffee production, and implementation of income diversification through intercropping, training, and technical assistance had a positive and significant relationship with the productivity of coffee. The number of active family members in coffee production was found significant and has a positive relationship with the productivity of coffee. The findings revealed that the very single additional active member, the productivity of coffee increased by nearly eleven units if all other variables were constant (Table 3). The finding is relatively similar with the outcome of other research done in Ethiopia by different authors (Gebre et al., 2021; Bhattarai., 2020; Temesgen and Getachew, 2018). Their report discovered that productivity significantly increases with the increase in the number of active family members. The active member of the family offers incentive care, which is required for the coffee plant to produce a high yield. The significance of the number of active family members in coffee production highlights that farm labor is an important factor in affecting coffee productivity.
The study showed that intercropping the crops in the coffee farm is not practiced in both districts. About 84.9% of the respondents were not intercropping other crops with their coffee. Only 15.1% of the respondents were use the mixed type of coffee cropping system. It is obvious that to increase the production and productivity of crops fertilizers application is crucial. Subsequently, about 31.7% of the respondents used organic fertilizer for their coffee farms. Of the different organic fertilizers, about 68.3% of respondents apply compost, cow dung, and farmyard manure to their coffee farms (Table 2).
Table 2
Descriptive statistics for continuous and categorical variables
Continuous variables | Mean | Max | Min | SD |
Age | 41.39 | 68 | 20 | 12.26 |
Family size | 6.22 | 19 | 1 | 12.93 |
Growing Experience | 20.74 | 60 | 5 | 11.51 |
Coffee Landholding | 2.04 | 8 | 1 | 1.07 |
Age of Coffee | 20.52 | 60 | 5 | 11.11 |
Categorical variables | | | | |
Education Level | | Number | | Percent |
· Illiterate/ Uneducated | | 106.00 | | 26.60 |
· Model (1–4) | | 81.00 | | 20.30 |
· Elementary (5–8) | | 135.00 | | 33.80 |
· Secondary (9–12) | | 68.00 | | 17.00 |
· Diploma (10 + 3) | | 9.00 | | 2.30 |
Weeding | | | | |
· Yes | | 266.00 | | 66.50 |
· No | | 133.00 | | 33.50 |
Gender | | | | |
· Male | | 363.00 | | 91.00 |
· Female | | 36.00 | | 9.00 |
Shade Using | | | | |
· Yes | | 393.00 | | 98.50 |
· No | | 6.00 | | 1.50 |
Intercropping | | | | |
· Yes | | 59.00 | | 15.10 |
· No | | 340.00 | | 84.90 |
Fertilizer Application | | | | |
· Applied | | 123.00 | | 31.70 |
· Didn’t Apply | | 266.00 | | 68.30 |
Insect | | | | |
· Antestia bug | | 6.00 | | 1.60 |
· Stem Borer | | 298.00 | | 74.60 |
· Berry Borer | | 67.00 | | 16.80 |
· Leaf Minor | | 28.00 | | 7.00 |
Diseases | | | | |
· Coffee Berry Diseases | | 281.00 | | 70.30 |
· Coffee Leaf Rust | | 22.00 | | 5.50 |
· Coffee Wilt Diseases | | 11.00 | | 2.80 |
· Root rot | | 85.00 | | 21.40 |
Where: Max-maximum; min-Minimum; SD- standard deviation |
The household survey indicated that two third (66.5%) of the coffee growers in the study area remove coffee weeds from their coffee farms (Table 2). Farmers who weed their coffee farms get more coffee yield than those farmers who don’t weed their coffee farms (Table 3). Different nutrients and minerals, water, and light are competed by weeds. If weeds are allowed to grow during the late post-rainy season period, they use the soil moisture that coffee needs in the subsequent dry season. Proper control of weeds typically has a positive effect on the bean size and flavor of coffee (Wintgens, 2004). Because of the diversity of weeds and the environmental conditions in the coffee growing areas, however, dependency on single weed management is not advisable. Therefore, farmers in the study districts should control weeds from their coffee farms by a combination of different weed control methods. Integrated weed control (IWM) would be the best strategy for sustainable coffee production (Anteneh et al.,2010).
Coffee diseases and insect pests are also other factors that can affect coffee yield and even quality.
About 70.3% of coffee farmers found coffee berry diseases (CBD) as a major disease that affects coffee yield. When coffee berry diseases attack the fruits in its more advanced stage of growth cause severe damage to the yield and as well as quality of coffee (Eshetu and Girma, 2008). The remaining 21.4%, 5.5%, and 2.8% of the respondents found root rot, coffee leaf rust, and coffee wilt diseases, respectively. Similarly, farmers also mentioned that insect pests like stem borer, berry borer, antestia bug, and leaf miner were among the factors that decline yield on their coffee farm in both districts. About 74.6% and 16.8% of the respondents in the study areas face stem borer and coffee berry borer, respectively. Whereas 7.0% and 1.6% of respondents reported incidence of leaf minor and antestia bug, respectively. Study results also showed that diseases like root rot, coffee leaf rust, coffee berry disease, insect pests like stem borer, berry borer and, leaf minor had a negatively significant effect on the productivity of coffee (Table 3). According to farmers consulted in the current study, the application of different cultural coffee managemental practices such as adding ash around coffee trees, burning diseased coffee trees, and killing the larvae manually by insects sticking into the hole burrowed by insects are traditionally exercised to control ants and stem borers. Further scientific studies on the effectiveness of these cultural methods of pest control are suggested to complement the farmers’ traditional pest management knowledge with research-based control evidence. That will have a positive effect on the sustainable management of the major coffee pest and subsequently sustain coffee productivity.
Table 3
Ordinary Least square (OLS) regression model for coffee yield.
Yield per Ha. | Coefficient | Robust Std, Err | t | P > t |
Age of HH | 0.0020 ns | 0.0013 | 1.5300 | 0.1270 |
Gender/Sex | 0.4112*** | 0.1450 | 2.8300 | 0.0050 |
Education level | 0.0517*** | 0.0043 | 12.0000 | 0.0000 |
Family size | 0.0079*** | 0.0012 | 6.7800 | 0.0000 |
Growing experience | 0.1263*** | 0.0328 | 3.8600 | 0.0000 |
Coffee landholding (ha) | -0.0087*** | 0.0014 | -6.1000 | 0.0000 |
The average age of coffee | -1.0478*** | 0.1188 | -8.8200 | 0.0000 |
Coffee intercropping | 0.0169ns | 0.0467 | 0.3600 | 0.7180 |
Weeding | 0.4299*** | 0.1570 | 2.7400 | 0.0060 |
Fertilizer Application | 0.0702*** | 0.0187 | 3.7600 | 0.0000 |
Shade using | 0.5327*** | 0.1506 | 3.5400 | 0.0000 |
Insect | | | | |
Antestia bug | -0.9415 | 0.4852 | -1.9400 | 0.0530 |
Stem Borer | -0.9614** | 0.4665 | -2.0600 | 0.0400 |
Leaf minor | -0.9577 | 0.5498 | -1.7400 | 0.0820 |
Coffee berry borer | -0.8440 | 0.4570 | -1.8500 | 0.0660 |
Diseases | | | | |
Coffee wilt diseases | -0.0706 | 0.1055 | -0.6700 | 0.5040 |
Coffee leaf rust | -1.1468*** | 0.1270 | -9.0300 | 0.0000 |
Root rot | -1.3208*** | 0.1205 | -10.9600 | 0.0000 |
Coffee berry diseases | -1.7512*** | 0.1854 | -9.4500 | 0.0000 |
_Constant | 4.9284*** | 0.3924 | 12.5600 | 0.0000 |
Number of observations | | 399 | | |
F (19, 379) | | 173.92 | | |
Prob > F | | 0.0000 | | |
R-squared | | 0.8971 | | |
Adj R-squared | | 0.8919 | | |
*, **and *** represent significance at 10%, 5% and 1% probability levels respectively.
Likewise, the coefficient of application of organic fertilizers is positive and significant, which implies that farmers who apply organic fertilizers to their coffee farms get more coffee yield than those farmers who don’t. This is because coffee is a highly nutrient feeder naturally.
The assessment of the study revealed that almost all the interviewed farmers use shade trees for their farms to produce coffee. Of the whole respondents, about 98.5% of them use shade trees for their coffee production in both districts (Table 2). The respondents in a general idea of shade trees were extremely positive and having shade trees was mentioned as a precondition for planting coffee trees on their farms.
The coefficient of shade use was also positive and significant (P = 0.01). Therefore, the coefficients of using shade trees for coffee production, indicate a 1% rise in using shade trees leads to an increase in coffee productivity by 0.53% (Table 3). The respondents also indicated that growing coffee under shade trees has many advantages i.e; improving soil fertility, increasing production and productivity, protects the coffee from the heavy sun and rain.
Planting shade trees on the coffee farm helps to safeguard the coffee plants from adverse environmental conditions like excessive sunlight, frost hail, and surplus wind speed. Coffee shade trees are crucial to shelter the newly planted coffee seedlings from undesirable environmental stress that make them stunted growth and wilted. They were also protective coffee plants from adverse climatic conditions during their flowering and fruiting stage. They improved the climate for coffee plants by protecting extreme temperatures in the air and soil and by lowering wind velocity in coffee farms. (Emire and Asfaw, 2018; Adugna and Paul, 2014 Santos et al., 2012; Claudia, 2010; Albertin and Nair, 2004).
3.1. Farmer’s Preference to shade tree species
The assessment of the study showed that the major shade tree species growing in both districts were Acacia abyssinica, Albizia gummifera, Cordia Africana, Grevillea robusta, Millettia ferruginea, Erythrina abyssinica, and Croton macrostachyus (Fig. 2). The current findings are similar to Sualeh et al. (2022) they reported Albizia species, Croton macrostachyus, Cordia Africana, Acacia abyssinica, Milletia feruginea, Ficus vasta and Grevillea robusta are the most usually expanded shade tree species in the study area.
The respondents in the study area have a deep knowledge of preferences of companionable shade tree species with coffee plants. From the usually growing shade tree species in both districts, Albizia gummifera, Acacia abyssinica, and Millettia ferruginea were the three top preferred shade tree species by farmers. Farmers prefer these shade trees because of their multiple advantages. These shade trees have high compatibility with coffee trees and wider canopy cover (crown) that provide better shade to coffee plants. Most of the coffee growers in Chora Botor (95.1%) and Limu Kossa (90.6%) districts showed more preference for coffee shade trees that have wider crown types (spreading types; like Albezia gummifera and Acacia abyssinica) than compact or narrow crown types (Table 5). Coffee shade trees that have the spreading type of crown shade provide better shade to coffee plants than the narrower one. They are also more important when there are sparsely distributed shade trees in coffee farms as they cover more areas. Coffee shade trees that have spreading types of crown shapes also allow light to filter onto the coffee trees. They have also small size leaves compared to other shade trees like Ficus vasta which has a larger leaf size. (. Almost all farmers at Chora Botor Limu Kossa (97%) prefer shade trees having small leaf sizes because smaller leaves produced smaller droplets when it rained and therefore caused less erosion, and the larger leaves are not easily decomposed as those smaller leaves. Farmers in the southern part of Ethiopia, also prefer well-suited shade tree species such as Ficus sur, Millettia feruginea, Cordia Africana, Albizia gummifera, Croton macrostachyus and Vernonia amygdalina, erythrina abyssinica (Emire and Asfaw, 2018; Ashenafi et al., 2014).
In the study site, coffee producers had long experience growing coffee plants under different shade tree species. Their overall impression of shade was very positive, and they believed shade was a precondition for coffee production systems. About 100% of the respondents in the area mentioned that shade trees found in their farms were older than 10 years (Table 4).
Table 4
Shade tree species characteristics at Limu Kossa and Chora Botor districts, Jimma Zone, Southwestern Ethiopia
Shade trees characteristics | Location |
Limu Kossa | Chora Botor | Overall |
(f) | (%) | (f) | (%) | (f) | (%) |
The average age of shade tree species | | | | | | |
About 10 years | 7.00 | 4.90 | 11.0 | 4.30 | 18.0 | 4.50 |
Between 11to 20 years | 26.0 | 18.3 | 41.0 | 16.1 | 67.0 | 16.9 |
Between 21 to 30 years | 25.0 | 17.6 | 44.0 | 17.3 | 69.0 | 17.4 |
Greater than 31 years | 84.0 | 59.2 | 158 | 62.2 | 242 | 61.1 |
Importance of shade trees | | |
Improves soil fertility. | 2.00 | 1.40 | 7.00 | 2.80 | 9.00 | 2.30 |
Increases productivity. | 3.00 | 2.10 | 12.0 | 4.80 | 15.0 | 3.80 |
Protects coffee from heavy sun. | 136 | 95.1 | 227 | 90.4 | 363 | 92.1 |
b/c of their compatibility to coffee | 1.00 | 0.70 | 2.00 | 0.80 | 3.00 | 0.80 |
For Construction | 1.00 | 0.70 | 1.00 | 0.40 | 1.00 | 0.30 |
Other | 0.00 | 0.00 | 2.00 | 0.80 | 3.00 | 0.80 |
Major shade tree species in coffee farms |
Albezia gummifera | 34.0 | 23.6 | 49.0 | 19.2 | 83.0 | 20.8 |
Acacia abyssinica | 42.0 | 29.2 | 52.0 | 20.4 | 94.0 | 23.6 |
Cordia africana | 15.0 | 10.4 | 39.0 | 15.3 | 54.0 | 13.5 |
Millettia ferruginea | 6.00 | 4.20 | 24.0 | 9.40 | 30.0 | 7.50 |
Erythrina abyssinica | 6.00 | 4.20 | 13.0 | 5.10 | 19.0 | 4.80 |
Croton macrostachyus | 24.0 | 16.7 | 43.0 | 16.9 | 67.0 | 16.8 |
Gravilia robusta | 17.0 | 11.8 | 35.0 | 13.7 | 52.0 | 13.0 |
Shade tree species under which coffee yield increased | | |
Albezia gummifera | 64.0 | 44.4 | 123 | 48.2 | 187 | 46.9 |
Acacia abyssinica | 66.0 | 45.8 | 75.0 | 29.4 | 141 | 35.3 |
Cordia africana | 3.00 | 2.10 | 14.0 | 5.5 | 17.0 | 4.30 |
Millettia ferruginea | 10.0 | 6.90 | 35.0 | 13.7 | 45.0 | 11.3 |
Erythrina abyssinica | 1.00 | 0.70 | 8.00 | 3.1 | 9.00 | 2.30 |
Where: f-frequency |
Coffee growers in Chora Botor and Limu Kossa districts prefer indigenous trees over exotic shade trees for their coffee (Table 5) for two main reasons: the long year of experience the farmers have in growing and using indigenous trees and the better adaptability of indigenous trees to the climate of the area over exotic ones. Coffee growers in Chora Botor (63.9%) and Limmu Kossa (77.3%) districts also prefer longer (> 15 m) shade trees for their coffee production (Table 5). Longer shade trees provide adequate sunlight to coffee plants so that the photosynthesis capacity of the plant would be improved. They can be also used for hanging beehives for honey production and timber production. However, coffee growers prefer shorter shade tree species on their coffee farms than longer shade tree shade trees in Costa Rica (Albertin and Nasir, 2004; Samuel, 2012). The reason could be the management for smaller shade tree species are simple and has less damage to coffee plants from different tending operations; shorter shade trees cause less erosion from droplets than taller shade trees.
Table 5
Shade Tree preference of coffee growers in Limu Kossa and Chora Botor districts, Jimma Zone, Southwestern Ethiopia
Shade preference | Location |
Chora Botor | Limu Kossa | Overall |
(f) | (%) | (f) | (%) | (f) | (%) |
Types of shade trees preferred |
Indigenous trees | 141 | 96.5 | 248 | 97.2 | 389 | 97.7 |
Exotic trees | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
Does not matter. | 3.00 | 3.50 | 7.00 | 2.80 | 10.0 | 2.30 |
Shade Trees height preferred |
Short (< 5m) | 2.00 | 1.40 | 7.00 | 2.70 | 9.00 | 2.30 |
Intermediate (10-15m) | 50.0 | 34.7 | 51.0 | 20.0 | 101 | 25.3 |
Tall (> 15m) | 92.0 | 63.9 | 197 | 77.3 | 289 | 72.4 |
Shade Tree crown preferred |
Spreading (wide) types of shade trees | 137 | 95.1 | 231 | 90.6 | 368 | 92.2 |
Compact types of shade trees | 7.00 | 4.90 | 20.0 | 7.80 | 27.0 | 6.80 |
Intermediate types of shade trees | 0.00 | 0.00 | 4.00 | 1.60 | 4.00 | 1.00 |
Shade tree leaf size preferred |
Shade trees have small leaf sizes. | 141 | 97.9 | 249 | 97.6 | 390 | 97.7 |
Shade trees have large leaf sizes. | 3.00 | 2.10 | 6.00 | 2.40 | 9.00 | 2.30 |
Shade trees with medium leaf size | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
No effect | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
Shade trees type preferred |
Deciduous trees | 18.00 | 12.5 | 63.0 | 24.7 | 81.0 | 20.3 |
Evergreen trees | 118 | 81.9 | 190 | 74.5 | 308 | 77.2 |
Both | 8.00 | 5.60 | 2.00 | 0.80 | 10.0 | 2.50 |
Where: f-frequency |
Most of the coffee growers at Chora Botor (81.9%) and Limu Kossa (74.5%) preferred evergreen shade tree species to deciduous types (Table 5), because of several advantages that evergreen shade trees can provide. To protect coffee plants from dangerous sunlight, especially throughout the dry season, evergreen shade tree species are the best. During the dry period, evergreen species are also used as animal feed. During the long dry season, the deciduous shade tree species shade out their leaves and then expose the coffee plant to extreme sunlight which directly affects the growth and development of the coffee plant.