SOIL PHYSICS AND WATER MANAGEMENT (SOPWAM) RESEARCH GROUP
The research group shall be known and addressed as Soil Physics and Water Management (SOPWAM) Research Group. It is to be domiciled at the Department of Soil Science and Land Resources Management. The soil being a finite resource is increasingly under pressure to effectively function as the homestead for agriculture and as the most vital component of the environment that regulates other components. Hence it is being stressed to deliver on its two primary, interdependent roles of providing food and ecosystem services for the teeming world population. The capacity of soils to perform these roles is, among other factors, seriously being undermined further by the contemporary global climate change and the attendant negative impacts. Of all regions of the world, tropical Africa is noted for its unequalled vulnerability to climate change. This is due mainly to unsustainable land use practices driven by not just ignorance but also by the high level of poverty and hunger prevailing in the region. The consequence of such unsustainable land use practices and climate change is widespread land degradation which often manifests as soil erosion of various forms and intensities, soil compaction, depletion of soil carbon stock, unfavourable aeration and soil moisture status, decrease in water reserve for agriculture, etc. As soil physicists and hydrologists, we have a task to proffer protocols for physical management and conservation of soil and water resources and to champion land use practices that will simultaneously promote agronomic productivity and ecological balance.
The research group recognizes the central role of the soil as a medium for biomass production, for storage of carbon and water, and for natural filtering of water. We also appreciate the fragile nature of our tropical ecosystems and the fact that judicious management of the soil resources is one way to cope with this situation, and so place emphasis on improving their (soils) quality. The group therefore aims to advance through research and teaching the understanding of soil physical properties and hydrological processes at different spatial and temporal scales. Also, simulation and prediction of soil physicohydraulic characteristics and transport processes in the unsaturated (vadose) zone is expected to lead to knowledge that will improve soil-water management and conservation techniques for sustainable development. Members of the research group have expertise in quantifying basic soil physical properties (including soil structure) and organic matter concentrations and judging soil quality and functions from them, as well as in understanding how these soil properties relate to soil hydrological processes.
We are interested in reconciling the structural stability characteristics of our tropical soils under field and laboratory conditions, such that fairly reliable inference can be made on erodibility of the soils from laboratory assessment of their structural (or aggregate) stability. By extension, the group is involved in surface hydrology particularly runoff management techniques to minimize soil loss to water erosion. We are also interested in the effects of agronomic and non-agronomic land use types on soil quality and soil physical conservation. Our research interest exceeds traditional soil research to edaphology. From this standpoint, we are interested in short- and long-term effects of soil/agronomic management practices (tillage, mulch, organic manures, biochar, irrigation, cover crops, cropping system/sequence) and agrochemicals on soil structure and stability, water conservation and crop performance.
Considering the decrease in agricultural water resource due to climate change, our research interest in physical edaphology also includes soil-water-plant relationships. Some key topics here include annual soil water budgeting to guide supplemental irrigation for production of selected crops in a tropical environment as ours characterized by distinct rainy and dry seasons, accurate field assessment and laboratory calibration of limits of available water in soils of contrasting texture and structure, determination of actual crop evapotranspiration (water use) and water use efficiency of selected cereals and legumes under alternative soil and agronomic management practices, etc.
Furthermore, our group is aware of some of the most important questions humanity is asking the world soil resources today, such as: can soils more than double food production in the next few decades, how is the soil interacting with the global carbon cycle and climate, how can land use minimize its adverse effects on the environment and improve soil function, etc.? And we appreciate the fact that field soil studies spanning decades are key to answering these questions. Our group will therefore recognize the importance of long-term soil-ecology observatories in understanding and explaining overall ecological responses to land/soil use, such as increases or decreases in biomass productivity and soil carbon sequestration, by designing some of our field research in edaphology to be on long-term basis.
In monitoring, characterization and quantification of soil structure, we hope to go beyond the visual field methods and traditional laboratory methods to advanced tomographic techniques (CT scanning). Similarly, our assessment of soil moisture content subsequently should also involve all aspects of time-domain reflectometry (TDR), ranging from detailed laboratory measurements for mobile systems to field-scale measurements of water content.
Composition of the group:
- S.E. Obalum (Coordinator)
- Mr V.C. Azuka (Staff member)
- J. Ene (Staff member)
- O.M. Njoku (Postgraduate student)
- O.W. Ishiusah (Postgraduate student)
- A.C. Ezenwata (Postgraduate student)
Some proposed research topics include:
- Prediction of consistency limits of soils from texture and organic matter concentration
- Erodibility of some southeastern Nigeria soils in relation to various methods of laboratory assessment of structural stability
- Impact of selected herbicides on soil structural properties and crop performance
- Soil moisture accretion and depletion patterns in profiles of three soils at the onset of rainy and dry seasons
- Field measurements of upper limit of available water and calibrations from laboratory measurements and soil physical properties
- Long-term effects of selected tillage systems on soil carbon sequestration and crop performance in the derived savanna