Agricultural production is a complex process particularly vegetable production including onion. The onion production is function of number of variables used in production process. The production of these vegetables depends on natural environment, input use and combination of inputs and management practices. Knowledge of the importance in relative terms of the resource inputs influencing the production of these vegetables is very essential for the producers for introducing desirable changes in their operations at the micro level, and for policy makers for formulating plans for improvement in the productivity of theses vegetables based on sound economic principles at the national level.
For assessment of on-farm production efficiency and returns to scale, production function analysis has been carried out. The production function has been estimated through input and output relationship of these vegetables produced.
This factor sum up the weight of different variables that are not easy to integrate in this investigation such as agronomical factors, weather condition, land and labor qualities, etc. In controlled environment research, no major significance is normally attached to this term because the exogenous factors to address are restricted [5
]. Since this study use survey so there exists a factors that are not incorporated because of different reasons which such analogy the intercept has shown significance in affecting the yield at 10 percent of significant level (Table 4).
Seed amount applied
Measuring seed amount applied per hectare in kilogram has no worth difference in yield so that increasing seed used above the recommended volume which is 3.5 to 4.0 kg per hectare (Table 3) have no impact in growing the output. Table 4 states that applying quantity of seed from the optimal extent will not rise yield as p-value indicates that insignificance at all level (Table 4).
It was measured in kilogram per hectare. Hassan and Ayoub [6
] stated that raising the level of nitrogen gave a high significant increment in total yield, average bulb size and reduces the percentage of bolting. Veck [7
] find out that the fertilizer application in developing country very low as Ethiopia is one of them, the fertilizer
application of onion in the districts are very low this needs further investigation but the perception is that apply fertilizer could not have implication in yield of onion for the irrigated areas as its assumed that the soil fertility is good yet the use have been found it had a contribution at significant level of 10% (Table 4).
Family members are the source labor for small scale irrigation users in the sample area, which the labor force affects the farm management and in which different operations are conducted. The family of the farmers is an important source [8
]. This variable was treated as continues variable as the matter of head count of the family and as stated in table 4 the t-value show (2.22) which greater that the expected t-values to significance (1.9) and found that it has an implication on the houses holds production system in labor force and farm management with significance level of 5%, which is indicating that the labor availability to daily activities in the production process can maintain for incremental output.
The level of education is assumed to have a high substantial importance and effect on the output. Which implies the better educated not only have the skill and knowledge but also the capacity for alternative methods and techniques than illiterate but also have more confidence in his own application technologies package which contributes to efficient production system. Education variable was a dummy variable literate or illiterate. Gladwin [9
] finding stated that education level affected yield. Supporting literatures states that education variable are significant in agricultural production at the household livelihood change, finding of this research supports that education have significant impact in the household output with t-value of 9.33 at the significant p-value of 1% (Table 4) that conditions the more educated the household there is a probability to get highest yield than that of non-educated household in the sample area which engaged in onion production at small scale irrigation level.
Age of the household leader
The variable was used as continues. Age is expected to have influence on productivity and production as it affects mental and technologies handling ability. Furthermore; it has innovative impression with experience. Ali (1990) disclosed that there is a positive relationship between household age and productivities up to certain level beyond which the negative because of mental and physical abilities to carry out activities. This study revealed that age had a positive impact in the onion producer households in the sample district with t-value of (7.08) at the significant level of 1% (Table 4).
Table 5 indicates that the production function used as a mode provided good fit to the data collected in 2014 from the district of Amibar and Fentale small scale irrigation user households is significant with F-value of 36.7 with significant level of probability at 1%. The coefficients of estimated parameters have the expected signs according to the economic theory.
Data analyzed for the cost of production at small scale irrigation producers of onion in the sample district average cost of production with keeping constant other exogenous variables that can contribute to the cost of investment the total cost of production per hectare on average is 18,247.3 Ethiopian Birr (Which is at the time of US Dollar exchange rate was1USD=19.97 Eth. Birr) which is almost 913.74 USD (Table 6).
Seed cost and weeding practices for labor have the highest share the total production cost. The recommended seed weight per hectare is 3.5 to 4.0 kg (Table 3) yet the sales cost of seed at the market level varies from 800 to 775 Ethiopian birr which escalating in every season that indicates the supply side is not at equilibrium compare the demand, on the other side it is an opportunity for small holder commercial farmers to produce to supply the market at the local market. Though fertilizer application is not recommended in the sample districts because the return from application is insignificant yet there are households who apply at a minimal level, average share of the fertilizer is negligible which was (3.94%) from overall average allocated per hectare. Pesticide had an average cost of 1,891.10 Eth. Birr which has the portion of (10.36%) from the gross cost, the suggested pesticides where Dime-tot (applied with 200-250 liters of water with 1.5 litters of Dime-tot for a hectare) and Celecron (200-300 liters of water with 1.5 litters of Celecron for a hectare) applied was used to protect tribes in the sample area which is also recommended by Werer Agricultural Research Center.
For calculating the break-even point and profitability of production these formula was used:
Break-even point = total cost of production per ha
Price per unit of yield in kg
18,247.3 birr = 4293.48 kg (which is at about 43 quintals per hectare)
The percentage part of the break-even point of the average onion yield was found:
4293.48x100 = 25.8% the equilibrium share to profit was 26% at this point
16650 of production the household average cost and yield are at optimal stage of production where it shows increasing at decreasing rate of returns from the break-even yield to the average yield the producer is at increasing rate of returns to production where profitability rate is generated to the household income.