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Optimising Water Resources Management For Increased Crop Water Productivity In The Humid Tropics: The Challenge Of A Changing Climate And Weather Variability

Congress: 2015
Author(s): Samuel Agele (Akure)


Keyword(s): Sub-theme 10: Management of water resources,
AbstractWorldwide, a range of shifts in climate over time translates to increased pressures and exploitation of water resources in addition to increases in water stress situations and high temperatures, and marginal growing environments. In future climates, greater heat and drought tolerance (increases in water use efficiency) in crops will be required. Climate variability calls for drastic changes in management of land and water resources. The pathways to achieving sustainable agriculture, water resources management and food security may include: raising the efficiency of rainfall capture and soil storage and optimizing water productivity of crops in rainfed, irrigated and dryland farming systems and adoption of water saving/conserving technologies. It is also necessary to use crops (drought tolerance and high water productivity) that will use less water and attain harvest. Studies of rainfall trends and catchment/watershed water balance useful for estimating water production functions, soil moisture adequacy for rainfed farming and necessity for irrigation (supplementary/full) should be widened. Climate change will affect hydrological cycle possibly through changes in intensity quantity and duration of precipitation, the amount of runoff and groundwater recharge rates, in addition to disappearance of significant areas of mangrove and coastal wetlands. Increased variability of climatic events would affect the ability of rainfall to effectively recharge ground water resources and may lead to diminished potentials of water resources globally. The degradation of water quality by increased microbial load and nutrient/effluent concentration in water (surface and ground water) resources and leakage of saline ground water into inland river systems and land surface, may result from increase in precipitation, run off (flow regimes) and temperatures. Easily recoverable ground water reserves will be depleted and the residual water remaining will be of inferior quality. The humid tropics is endowed with abundant inland valley swamps (inland wetlands) that are characterized by shallow water table depths while the residual soil moisture storage and capillary rise/upflows from the water table contribute to crop rootzone moisture storage. Above ground (surface) flood levels are obtained in months of frequent high intensity rainfall, high humidity and low temperature. Reduced irrigation above water tables does not only results in more efficient use of water resources, but it may also lower the risk of water logging below the root zone and improvements in water productivity (water- yield/water production function) and drought response factor Ky of crops. Information is required on irrigation scheduling and crop water requirement to enhance knowledge on how best to incorporate upflows (capillary rise) from shallow water tables and the optimisation of ground water contributions to crop yield and the development of management guidelines for irrigating crops grown on inland valley swamps. Thus, the development of water efficient farming systems, increased drought related research efforts and crop varieties fall within the framework of ecologically sound management of water resources.
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