http://hdl.handle.net/123456789/1391 2026-04-14T23:28:14Z 2026-04-14T23:28:14Z Darko, Ransford Opoku Shouqi, Yuan Haofang, Yan Junping, Liu Abbey, Agnes http://hdl.handle.net/123456789/4439 2021-01-04T09:23:55Z 2016-05-01T00:00:00Z

Calibration and validation of Aqua Crop for deficit and full irrigation of tomato Darko, Ransford Opoku; Shouqi, Yuan; Haofang, Yan; Junping, Liu; Abbey, Agnes The objective of this study was to calibrate and test Aqua Crop for tomato (Lycopersicon esculentum) grown under deficit and full irrigation. Two field experiments were carried out in the tropical humid coastal savanna zone in Mfantseman district of the Central Region of Ghana. Data from the first experiment were used to calibrate the model while data obtained from the second experiment were used to validate the model. The calibrated Aqua Crop model concentrated on its performance to predict crop yield and seasonal crop water requirement (ETc). Four treatments were investigated: T1 (no irrigation after plant establishment), T2 (50% ETc restoration), T3 (100% ETc restoration up to beginning of flowering, then 50% ET c restoration) and T4 (100% ETc restoration). The results revealed that Aqua Crop was able to simulate the yield of tomato for T2-T4 with the exception of Treatment T1 which was simulated with the highest deviation of 45.1%. On the other hand, the model was able to simulate the seasonal water requirements to an appreciable degree in both experiments. It must be pointed out that the calibration of Aqua Crop suffered from a lack of data on the progress of crop canopy cover which is a very important parameter used in developing the model 7p:, ill.

2016-05-01T00:00:00Z Minde, Isaac Terblanche, Stephanus Bashaasha, Bernard Madakadze, Ignacio Casper Snyder, Jason Mugisha, Anthony http://hdl.handle.net/123456789/4437 2021-01-04T09:03:58Z 2015-03-01T00:00:00Z

Challenges for agricultural education and training (AET) institutions in preparing growing student populations for productive careers in the agri-food system Minde, Isaac; Terblanche, Stephanus; Bashaasha, Bernard; Madakadze, Ignacio Casper; Snyder, Jason; Mugisha, Anthony Purpose – Agricultural education and training (AET) institutions will play a strategic role in helping to prepare Africa’s rapidly growing youth populations for productive careers in agriculture and related agri-businesses. The purpose of this paper is to examine the magnitude of skills and youth employment needs emanating from high-population growth rates. It then explores how agricultural education institutions are responding to these challenges in four different countries at different levels of food system development: South Africa tier 1, Tanzania in tier 2 and Malawi and Uganda in tier 3. Design/methodology/approach – Demographic and school enrolment data provide information on the magnitude of job market entrants at different levels of education while Living Standards Measurement Studies in the respective countries provide a snapshot of current skill requirements in different segments of the agri-food system. In order to evaluate AET responses, the authors have conducted country-level reviews of AET systems as well as in-depth assessments at key tertiary AET institutions in each of the four case study countries Findings – Growth rates in primary school enrolments are high in sub-Saharan Africa. At the same time, because of budgetary constraints, transition rates decline rapidly – about 40 percent from primary to secondary and 7 percent from secondary to tertiary. As a result, substantial numbers of primary and secondary school graduates seek jobs. Research limitations/implications – The case study countries are limited to four. Had more financial resources and time been available, researchers could have spread further afield and in so doing increasing the precision of the results. Originality/value – Estimation of the number of primary and secondary school leavers seeking employment because of failure to proceed to the next level of education. Estimation of the level of education shares in the various components of the agri-food system 35p:, ill.

2015-03-01T00:00:00Z Liu, Junping Yuan, Shouqi Darko, Ransford Opoku http://hdl.handle.net/123456789/4436 2021-01-04T08:53:25Z 2016-04-22T00:00:00Z

Characteristics of water and droplet size distribution from fluidic sprinklers Liu, Junping; Yuan, Shouqi; Darko, Ransford Opoku A new prototype of fluidic sprinkler (PXH) is proposed and its working theory is reported. The hydraulic performance of four different types of sprinkler head (PXH, PY, Toro S 800 and RainBird S 3504) was compared at the same operating pressure. Meanwhile, PXHs with nozzle diameters of 4, 6 and 8 mm were tested to establish a mathematical model of water distribution and droplet diameter. The results show that the PXH produces the longest wetted radius, potentially due to its unique working principles. The PXH exhibits optimal water distribution performance because the air in the nozzle destroys the fluid structure of the water jet. The PXH results in the smallest droplet diameter, which transfers less kinetic energy to the soil. The results from the empirical equations of a distribution model from the PXH were plotted against actual values to obtain regressions, with coefficients of determination ranging from 95.1 to 98.8%. The droplet size model was determined by fitting the experimental results obtained using different operating pressures and nozzle diameters. The model was verified using the experimental results of six cases with different droplet diameters. The average relative error between the predicted and measured droplet diameters was 4.6%. 8p:, ill.

2016-04-22T00:00:00Z Umego, Okwunna M. Ewemoje, Temitayo A. Ilesanmi, Oluwaseun A. http://hdl.handle.net/123456789/4435 2020-12-21T15:15:37Z 2018-09-02T00:00:00Z

Comparative study of evapotranspiration variation and its relationship with other climatic parameters in Asaba and Uyo Umego, Okwunna M.; Ewemoje, Temitayo A.; Ilesanmi, Oluwaseun A. This study was carried out to assess the variations of Reference Evapotranspiration (ETO also denoted with RET) calculated using FAO-56 Penman Monteith model of two locations Asaba and Uyo and evaluate its relationships with the variations of other climatic parameters. Meteorological data of forty one years (1975-2015) and thirty five years (1981-2015) period for Asaba and Uyo, respectively gotten from Nigeria Meteorological Agency, Abuja were used. It was observed that the variations of Evapotranspiration (ET) in both locations were in line with two seasons (rainy and dry) normally experienced in Nigeria having its highest value in March (4.8 mm/day) for Asaba and for Uyo in February (4.5 mm/day); and its lowest value in August (3.1 mm/day) for Asaba and in July (2.9 mm/day) for Uyo. ET variation when compared with other climatic variables in both locations was observed to have the same trend with maximum temperature, solar radiation and sunshine hours. It also has the same variation with minimum temperature though with slight deviation. It was observed that ET variation is inversely proportional to the variation relative humidity. Wind speed displayed relatively small variation in its trend over the study period and is not in line with the variations of ET 7p:, ill.

2018-09-02T00:00:00Z