WAILEPO: EXPLORING SOIL POROUS SYSTEM CHANGES AND EVALUATING POINT PEDOTRANSFER FUNCTIONS TO PREDICT SOIL WATER RETENTION FOR SOME HAWAIIAN SOILS

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dc.contributor.advisor Deenik, Jonathan L.
dc.contributor.author Lam, Kristy Izumi
dc.contributor.department Natural Resources and Environmental Management
dc.date.accessioned 2021-09-30T18:16:38Z
dc.date.available 2021-09-30T18:16:38Z
dc.date.issued 2021
dc.description.degree M.S.
dc.identifier.uri http://hdl.handle.net/10125/76438
dc.subject Soil sciences
dc.subject Agriculture
dc.subject Natural resource management
dc.subject agriculture
dc.subject lepo
dc.subject pedotransfer functions
dc.subject soil pores
dc.subject soil water retention
dc.subject tropical soils
dc.title WAILEPO: EXPLORING SOIL POROUS SYSTEM CHANGES AND EVALUATING POINT PEDOTRANSFER FUNCTIONS TO PREDICT SOIL WATER RETENTION FOR SOME HAWAIIAN SOILS
dc.type Thesis
dcterms.abstract Soil water retention facilitates soil physical, chemical, and biological processes. Understanding soil water retention behavior across a mineralogically diverse range of agricultural soils is essential to soil and water stewardship in Hawaiʻi. In this research, we first examined soil porous system changes based on soil type, management, and depth. Although there were no significant differences in ultramicropore contribution and no depth effects across treatments, there were mineralogical differences in total porosity, macro-, meso-, and micro-pore contribution, indicating that soil mineralogy influences soil pores and ultimately soil hydraulic behavior. While the Tantalus (ferrihydritic Andisol), Wahiawā (kaolinitic Oxisol), and Waialua (halloysitic Mollisol) experienced an overall decrease in mesopore contribution under cultivation, the opposite was seen in the Kula soil (allophanic Andisol). Kula’s intriguing behavior may be attributed to the combined effects of cultivation intensity, soil organic matter loss, and irreversible drying thereby causing permanent changes to the soil porous sytem. Second, we developed pedotransfer functions (PTFs) to predict water retention at -10 kPa based on key soil physical and chemical properties and compared the gene expression programming (GEP) and multiple linear regression (MLR) approaches on PTF performance. Sensitivity analyses revealed that total organic carbon was the strongest water retention predictor at -10 kPa followed by non-crystalline aluminum across six soil types. Furthermore, the GEP-based PTF outperformed the MLR-based PTF, indicating that GEP is superior and more reliable than the traditional MLR approach. Overall, our results suggest that allophanic Andisols have unique soil porous systems and water retention properties that set them apart from their crystalline counterparts. Future studies should investigate crystalline soils separately from non-crystalline soils and explore using soil structural properties as PTF predictors.
dcterms.extent 111 pages
dcterms.language en
dcterms.publisher University of Hawai'i at Manoa
dcterms.rights All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
dcterms.type Text
local.identifier.alturi http://dissertations.umi.com/hawii:11158
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