Characteristics of soils derived from ultramafic rocks in Homonhon Island, Philippines

photo0091Miguel Francisco B. Abulencia and Faustino P. Villamayor, 2013 *( 


The prevalence of mining activities in Homonhon Island, Philippines has affected the soil resources and the agricultural livelihood of the people in the island. Thus, this study aims to determine the physical and chemical properties of the soils and recommend suitable tree species for revegetating the area.

Five pits representing specific positions in the hillslope (i.e., summit, shoulder, backslope, footslope, and toeslope) were selected and representative soil samples from each horizon of the pit were collected for analyses following standard procedures.

Soils have pH values ranging from 5.5 – 6.8 and low potential CEC values of <34 cmol(+)/kg with the presence of kandic horizon in all soils except for the backslope which has cambic horizon. Moreover, soils generally have decreasing organic matter content and available P with increasing depth. All the soils except for the backslope are classified as Kandiudults while the backslope qualified as a Dystrudept.

Acid-tolerant species such as Piliostigma malabaricum is suitable in the area. Morover, no-tillage and or contour hedgerow can be applied in the hillslope so as to minimize soil erosion. Addition of organic materials through green manuring is beneficial as it does not only promote aggregation but also serve as a source for nutrients.

keywords: ultramafic rocks, mining activities, Piliostigma malabarcium


Serpentine in Homonhon Island, Philippines

Novice Soilist

These were the rocks I found somewhere in Homonhon Island, Phils. during the field sampling for my undergraduate thesis.

*For size reference, my foot size is 10″.

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Mineral Nutrient Contents of Soil and plant tissues of Abaca (Musa textilis.Nee) in areas infected with the Abaca Bunchy Top Virus (ABTV) in Leyte and Southern leyte

3Jertz Vlyn D. Escala* and Romel B. Armecin, 2013 *(


This study was conducted in the different abaca growing areas in Leyte and Southern Leyte infected with abaca bunchy top virus (ABTV).  This was done to assess the biomass, nutrient availability, nutrient status, and evaluate the amount of nutrient present in the plant tissues of non-infected and infected plants.  Soil and tissue samples were collected in the different abaca growing areas and these were brought to the laboratory for analysis.

Among the sites sampled, % ABTV infection was higher in Ormoc site and the biomass was higher in non-infected than the infected plants.  Phosphorus and magnesium contents of soil and plant tissues in Ormoc site were low while potassium (K) and iron (Fe) contents were higher.  Nitrogen (N), phosphorus (P), calcium (Ca), magnesium (Mg) and manganese (Mn) were higher in concentration in the leaf tissues. Pseudostem tissue had higher concentration of P and Ca while iron (Fe) and zinc (Zn) in corm tissue.  This finding suggests that ABTV infection reduce the biomass of abaca. Low P and Mg in the soil could contribute to high incidence of infection.

Mobility of cadmium and lead in soils derived from limestone

 Ariel B. Bolledo1 and Beatriz C. Jadina2


1Science Research Assistant, Philippine Higher Education Research Network, Visayas State University (

2Associate Professor, Department of Agronomy and Soil Science, Visayas State University (



Soil accumulation of heavy metals coming from industrial and municipal wastes poses contamination risk to groundwater resources. A leaching experiment was conducted to determine the mobility and retention of cadmium (Cd) and lead (Pb) in soils derived from limestone and to relate the properties of such soils to the mobility and retention of cadmium (Cd) and lead (Pb). A 2 x 5 factorial leaching experiment consisting of two heavy metals, cadmium (Cd) and lead (Pb), and five different Cd and Pb concentrations (0, 50, 150, 250, 350 mg l) was conducted. Solutions containing Cd(NO3)2·4H20 and Pb(NO3)2 were used as sources of Cd and Pb respectively. The leaching experiment was conducted for 60 hours. Results showed that the electrical conductivity (EC) and pH of the leachates were high at the first 12-h of leaching which decreased as the leaching process was continued. The different concentrations of Cd and Pb did not significantly affect the EC and pH of the leachates. Most of the recovered concentrations of Cd and Pb in the leachates from all the treated soil columns were below the detection limit. In terms of mobility, Pb was found to be more mobile than Cd. However, the concentrations recovered for both Cd and Pb were very low (0.0035 – 1.77 mg l) which implies high sorption of the heavy metals. Hence, mobility of Cd and Pb was not evident in soils derived from limestone. Fractionation analysis of Cd and Pb in soil revealed the dominance of carbonate-bound fractions which supports the observation of heavy metal immobility. High cation exchange capacity and high calcium carbonate content were the soil properties related to mobility of the heavy metals.

Comparison of soil degradation processes in selected degraded uplands in Samar island

IMG_4967Dernie T. Olguera* and Victor B. Asio, 2013 *(


This study evaluated the dominant soil degradation processes in selected degraded uplands of Samar Island, determined the important factors influencing soil degradation in the selected sites and identified the indicators of soil degradation.Two (2) sites were selectedin Sta. Rita, Samar and Salcedo, Eastern, Samar representing the western and eastern sides of Samar Island respectively, were selected.

Soil erosion is the major soil degradation process in the degraded upland studied. It resulted not only in considerable soil losses but nutrient losses as well. Soil erosion varied with vegetation cover and site. It was much higher in the sweetpotato, cassava, and gabi crops than under natural vegetation. In addition, soil erosion was higher in Salcedo than in Sta. Rita which is related to climatic and soil characteristics. Bulk density, porosity, aggregate stability, soil pH, organic matter, and carbon dioxide evolution are good indicators of soil degradation. Dominance of Saccharum officinarum, Imperata cylindrica, Melastoma affini and Psidium guajava indicated degraded soil condition. Farmer’s practices particularly clean culture and organic fertilizer application influenced the degree of soil degradation.

Keywords: soil degradation, soil erosion, degraded uplands, Samar Island