Thursday, May 13, 2010
Soil excursion to Southern Leyte, Philippines with Prof. R Jahn
On 09 April 2010, we organized a soil excursion to Southern Leyte for selected graduate students pursuing MSc degree in Soil Science at the Department of Agronomy and Soil Science of Visayas State University in Baybay, Leyte. The main objective of the activity was to observe the important soils of the province.
Prof. Dr. Reinhold Jahn of Martin Luther University (Germany), former Chairman of the Soil Geography Commission of the International Union of Soil Sciences (IUSS), served as the resource person. The participants included Grace Enojada, Marilou Sarong, Katrina Piamonte, Deejay Maranguit, Glenn Largo, and Raffy Rodrigo.
The group first focused on the young soils in the alluvial plains which are generally used for lowland rice production. Prof. Jahn discussed the important features of paddy (rice) soils particularly gleying, mottling, and the occurrence of plow pan.
During his recent field work in the Banaue rice terraces in northern Luzon, Prof. Jahn noted that plow pan is generally absent in the rice terraces since puddling is not part of the normal cultural managment practices there. Puddling is the process of destroying the structure of rice soil by cultivating it when it is wet inorder to homogenize the soil and to produce a watertight soil paste to hold water on the soil surface.
In the mountainous portion of Southern Leyte, highly weathered soils (Ultisols) that developed from basalt and other igneous rocks are widepsread. The group examined an Ultisol soil profile that was very deep and heavy clay, and which showed the occurrence of mottles and exfoliation weathering of rock in the lower portion of the profile. Ultisols are acidic, clayey, and have generally low nutrient status. They are the most widespread soils in the Philippines.
The group also found a very beautiful soil profile of an Ultisol near the town of Silago. It formed from two parent materials (bisequm) and clearly showed lithologic discontinuity (i.e. the heterogeneity of the parent rock material).