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.
Dernie T. Olguera* and Victor B. Asio, 2013 *(email@example.com)
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
Influence of soil physical factors like soil compaction has been known to affect root growth and tuberous root development of sweetpotato. This physical factor is often left-out in the evaluation of newly released cultivars of sweetpotato. A pot experiment was conducted to evaluate the growth and yield responses of sweetpotato cultivars to various levels of soil compaction and to determine the degree of soil compaction that would result in optimum growth of various sweetpotato cultivars. A 4 x 3 factorial experiment with 4 sweetpotato varieties (PSB SP-16, PSB SP-17, PSB SP-25 and Ciete Flores) as factor A under 3 levels of compaction (1.1, 1.3 and 1.5 g cm-3 bulk density) as factor B was conducted. Results showed that depth of tuberous root formation and number of marketable tuberous roots decreased with the increasing degree of soil compaction. Other growth and yield parameters were not significantly affected by the treatments applied. Interaction effect of sweetpotato cultivars and levels of soil bulk density was significant on depth of tuberous root formation and number of marketable tuberous roots. Observation on the nature of formation, penetration, distribution and direction of tuberous root development showed that those at lower degree of compaction (1.1 g cm-3), tuberous roots were evenly distributed and were able to penetrate vertically and formed at deeper parts of the soil layer. However, the tuberous roots in compacted soils (1.3 to 1.5 g cm-3) were formed at shallower depths andwere not able to penetrate deeply.
Keywords: Compaction, Bulk Density, Sweetpotato cultivars, Tuberous root formation,
The steep and unstable topography of Abuyog, Leyte and recent landslide occurrences in the area particularly in Canmarating and Tadoc justifies the need for soil characterization of the landslide areas of the place. This research was conducted to determine the physical and chemical properties of soils from the landslide areas in Abuyog, Leyte and relate these to landslide occurrences. Two landslide cuts from different sites were evaluated using representative soil profiles which were examined in the field and sampled for the analysis of physical properties including particle size distribution, bulk density, particle density, total soil wet density, porosity, field capacity and water holding capacity, hydraulic conductivity, Atterberg limit and some chemical properties including pH, organic matter content, cation exchange capacity, and exchangeable sodium content.
Soils from the two landslide areas in Abuyog, Leyte generally have clayey texture, low bulk density, high total soil wet density, average particle density, porosity, moderately high saturated hydraulic conductivity, high liquid limit, and plastic index with very strongly to moderately acidic pH, high organic matter in surface and low at subsurface layers, moderate CEC and exchangeable Na.
Keywords: landslide, physical, chemical, plastic limit, Atterberg limit