PROJECT SUMMARY OF DOCTORAL THESIS
The working title of the thesis
“Evaluation of water saving technologies for the production of African Leafy Vegetables in a semi-arid environment in Kenya”.
Name: Francis Osia Odula
Institute: Institut für Gartenbauliche Produktionssysteme
Section: Systemmodellierung Gemüsebau
Agricultural production globally is inhibited by limited water availability. Regardless of this, the demand for water has more than doubled compared to population growth in the last century. Conversely, the erratic climate change that we are experiencing makes rain feed agriculture unreliable. Kenya is classified as a water scarce nation with 80% of the land mass falling under arid and semi-arid. The little water available for irrigation is massively wasted through inefficient irrigation methods such as overhead and furrow irrigation.
African Leafy Vegetables (ALVs) demand has increased owing to their significance as sources of human nutrients and household incomes. As a result, ALVs production has been intensified in urban and peri-urban areas which are often faced with intermittent rainfalls between rainy seasons. Use of water saving strategies to produce ALVs during the dry season is extremely useful in optimizing farmers’ returns when the supply is low in the market. Similarly, water saving technologies production ensures continued supply, which ensures stability in the prices of vegetables in the market thus enabling even the low-income individuals to access them. Irrigation and water saving techniques that utilize water efficiently are therefore required. The scope for increasing water use efficiency (WUE) is considered large and WUE can be increased by reducing unproductive water losses through evaporation barriers like mulches or improved irrigation techniques like drip irrigation, or by better meeting the physiological requirements of crops. DI and PRD have been applied to many crop species. In potato and tomato, use of DI and PRD irrigation strategies reduced water use by 20–30% with no significant yield loss and increased irrigation water use efficiency by 10-40%.
Mulch has several uses but water conservation and soil erosion control are the most important uses particularly in arid and semi-arid areas. Other benefits of mulching include soil temperature modification through control of temperature fluctuations, weed control through minimizing weed infestation in the farm, soil conservation, and addition of nutrients to the soil, soil structure improvement and increase in quality and yield of crops. Previous workers have shown that mulching has been effective in conserving soil moisture and increasing the productivity of crops such as in maize, turmeric, and sunflower. Integration of irrigation with mulching as a water saving strategy has the potential for better ALVs production and yield and to reduce the number of irrigation cycles. Since majority of AIVs growers are small-scale farmers with limited resources and considering the nutritional value, food security and economic potential that Ethiopian kales and spider plant offer, this study aims at assessing how water saving strategies such as deficit, PRD and drip irrigation, reduced tillage and mulching materials can be used to increase production of ALVs while at the same time save water without compromising the yield and quality of AIVs. The overall goal of this study is to develop water saving technologies to reduce the amount of irrigation and maintain optimal high yield and quality of Spider plant (Cleome gynandra (L.) Briq.) and Ethiopian kale (Brassica carinata).
Develop technologies to reduce water use and improve water supply for high yield and quality Spider plant and Ethiopian kales as ALV model crops
1. To determine the optimal amount of water and water saving strategies for Spider plant and Ethiopian kales production
2. To construct a mechanistic model which can assist in the development of water saving strategies for improved water use efficiency and productivity
1. There are thresholds for water deficits within which yield and quality are not negatively affected but significant water savings are possible.
2. Strip tillage, ridge tillage and mulching, reduce unproductive evaporation resulting in yield increase and produce quality