Determination of a location-specific Soil Hydraulic Quality (SHQ) index : a case study from northeast Thailand | |
| Author | Azam, Mohammad Gausul |
| Call Number | AIT Thesis no.AS-04-09 |
| Subject(s) | Soil moisture--Thailand Cropping systems--Thailand |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science. |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. AS-04-09 |
| Abstract | Assessment of soil hydraulic quality (SHQ) became a great concern in recent years in the context of agricultural sustainability. It cannot be measured directly, only relative measurements of the complex interaction of different 'key' properties of soil can be made. The main objective of the study was to develop location-specific SHQ indexes for the major cropping systems in the study area. Farmers' interviews and group discussions were made to characterize the land-use history of the area and to identify the driving forces of the land-use changes. 37 sites representative of 4 cropping systems were selected for a detailed characterization of soil hydraulic properties - based on stratified soil sampling (for the Ap horizon and the rooted subsoil)- in order to develop location-specific soil hydraulic quality (SHQ) indices. The first approach, factor-by-factor comparison, could not draw a conclusive summery on the changes of soil hydraulic characteristics under different cropping systems and management practices. The second approach, which consists of principal component analysis (PCA) and factor analysis, was able to develop a comprehensive SHQ index for each selected site. After the conversion of natural forests into arable land, the farming systems were subsistence oriented, mainly based on indigenous knowledge. Later on, the farmers adopted the use of 'modem' technology, such as new crop varieties, tillage implements and external inputs (fertilizers and pesticides). The driving forces of these land-use changes were, e.g., better yields, growing market demand, increasing prices for the produce, costs of external inputs - including labor-, labor availability, perceived changes in the rainfall pattern, increasing severity of pests and diseases, and the development of the infrastructure. Due to the diverse pathways of land-use change, there are presently 8 major cropping systems in the area, with maize is the main component, followed by cassava and sugarcane. Since these systems are market oriented and mostly based on high yielding crop varieties - mainly hybridsfarmers need to use increased levels of inputs to maintain the expected yields. For the Ap horizon, 8 soil properties were identified as the main indicators of SHQ. Most of these indicators are physical soil properties; more specifically, soil-structure related properties. These properties were used as the minimum dataset (MDS) for the construction of the SHQ index for each of the selected sites.Three distinctive SHQ index ranks were identified for the selected cropping systems, i.e., rank 1 - mungbean-maize; rank 2 - maize-fallow and cassava; and rank 3 - maize-maize. The mungbean-M aize system scored the highest SHQ index showing its significant (p 50.05) superiority in sustaining SHQ. However, for the different land- and crop husbandry practices, no significant differences (p 50.05) could be identified. For the rooted subsoil, no significant differences could be identified, irrespective of cropping system and management practices. The SHQ assessment successfully describes the essential conditions for the optimum soil water regime of the locality and can be used as significantly valid location-specific indicators within the context of the prevailing land-use and land management. Locations with overall poor SHQ can undoubtedly be improved by more appropriated cropping systems and the enhancement of land management practices. The mungbean-maize rotation is an example of such a system. |
| Year | 2004 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. AS-04-09 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Aquatic Systems(AS) |
| Chairperson(s) | Zoebisch, Michael A.; |
| Examination Committee(s) | Ranamukhaarachchi, S.L.;Clemente, R.; |
| Scholarship Donor(s) | Danish International Development Assistance (DANIDA);Asian Institute of Technology Fellowship |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2004 |