Category Archives: Volume 13 Nos. 1 – 4 (1991)

The effect of slope on the erosion coefficient of Umingan, Maasin and Malitbog clays


Author(s): Alan L. Presbitero and Vincent Christian Quimbo

Abstract

The effect of percent slopes on the erosion coefficient of Umingan, Maasin and Malitbog clays was found to be highly significant. For all the soil types, erosion coefficient had a positive relationship with the slope. Third degree polynomial equations described the slope-erosion coefficient relationship for Umingan and Malitbog clays, and quadratic equation for Maasin clay.
Umingon clay had the highest erosion coefficient at all slope levels, i.e. from 2.5 to 50% at an increment of 2.5%, while Malitbog clay had a higher coefficient than Maasin clay only at slope >17%.

Keywords : Erosion coefficient.

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Characteristics and ecological qualities of soils in a degraded upland in Negros Oriental


Author: Victor B. Asio

Abstract

Degraded uplands are widespread in the country but only limited information is available about this type of ecosystem. In view of this, a study was conducted to evaluate the characteristics and ecological qualities of soils in a degraded upland area in Manjuyod, Negros Oriental. Results indicated that the soils have generally poor characteristics and ecological qualities. This can be attributed to pedologic factors such as poor soil development and steep slopes as well as anthropogenic effects particularly cultivation and inappropriate land use systems. It appears that the degradation of the upland area is closely related to the impaired ecological functions of the soil. On-site and off-site ecological impacts of soil degradation occur primarily due to severe erosion sedimentation.

Keywords : Catena. Degraded upland. Ecological impact. Ecological soil qualities. Soil characteristics.

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The calculation of water release policy for Balog-balog (Philippines) single multipurpose reservoir system using DDDP analytical technique: 1. Model Development


Author: Alan L. Presbitero

Abstract

The monthly water release operating policy for a single multi-purpose reservoir system at each stage of development of the service area was defined using Discrete Differential Dynamic Programming (DDDP) optimization analytical technique and simulation model developed in a master program for a mainframe computer type. Irrigation and flood control were the primary and secondary purposes, respectively, of the reservoir system with hydroelectric power generation as the by-product of the system’s operation.
The recorded (historical) monthly streamflow data used in the study was subjected to the following analyses prior to generating a number of sequences of 50-year monthly streamflow data, namely: identification of probability distribution that best described the recorded streamflow data, and the determination of trend and periodicity using the 3- Parameter Log-Normal (3PLN) probability distribution function (pdf) and power spectrum analysis, respectively. The Thomas-Fiering streamflow model was used to generate the sequence of 50-year monthly streamflow data.

Keywords : DDDP. Optimization. Power spectrum analysis. Reservoir system. Simulation model. Streamflow data. Thomas- Fiering model. Water release policy. 3PLN.

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Influence of inoculum density of root-knot nematode (Meloidogyne incognita [Kofoid & White] Chitwood) and plant age on yield of ampalaya


Author(s): F.A. Salares and R.M. Gapasin

Abstract

A pot experiment was conducted to determine the most susceptible stage of growth of ampalaya, Momordica charantira L. to the root-knot nematode, Meloidogyne incognita infestation and the inoculum density of the nematode that could affect the yield.
Gall and egg mass indices and nematode population recovered from the roots and soil were significantly higher in 2-and 4-wk old plants compared with 6- and 8- wk old plants regardless of inoculum density. Likewise, plants inoculated earlier had heavier root weight compared with plants inoculated at later stage but not the fresh weight of vines. Fresh root and vine weight were generally heavier at inoculum density regardless of age of the plants.
Total fruit yield of 2- and 4- wk old plants inoculated with 1,000 and 5,000 eggs were reduced by 68 to 70% and increased to 81 to 82% when inoculum density was increased to 10,000 and 20,000, respectively. Percent yield reduction was lower on 8-wk old plants regardless of inoculum density compared with 2-,4- and 6-wk old plants; however, percent yield reduction at his growth stage increased as inoculum density was increased.
Interaction effects of inoculum density versus age of plant on the production of galls and egg masses, fresh vine weight and weight of marketable and non-marketable fruits were significant.

Keywords : Ampalaya. Egg mass index. Gall index. Inoculum density. Meloidogyne incognita. Momordica charantia. Root-knot nematode. Yield.

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Static pressure drop in a fixed bed of root crop chips during drying as affected by airflow rate and moisture content


Author: Ramon R. Orias

Abstract

Pressure drop (mm H20/m depth) was generally higher in high-moisture chips than in low-moisture chips. Relationships were found to be normally linear for sweetpotato (Ipomoea batatas) and taro (Colocasia esculenta) and logarithmically linear for cassava (Manihot esculenta). Porosity also increased with moisture, but despite the presence of more void fraction, pressure drop remained high. This was primarily because interspaces in the bed were lined with starch granules and water molecules, thus suppressing the flow of air. When dried, chips decreased in volume and weight and exposed smooth surfaces, thereby causing less resistance to airflow. Among the empirical equations that had been evaluated, the Ramsin and Ergun equations fitted very well with the experimental data. The coefficient of
Determination, r2 ranged through 0.94-0.99. The chips compared to grains such as sorghum (Sorghum bicolor), rough rice (Oryza sativa), shelled corn (Zea mays), and soybean (Glycine max).

Keywords : Airflow. Bed porosity. Empirical equations. Moisture content. Root crop chips. Static pressure drop.

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Detoxification and utilization of wild yam (Dioscorea hispida Dennst.) flour as binder in meat loaf


Author(s): Linda S. de la Rosa and Linda B. Mabesa

Abstract

Wild yams (Dioscorea hispida Dennst.), locally known as nami or kot, was detoxified and processed into flour. Detoxification was carried out by salting thinly-sliced tubers and subsequently washing these under running water. Results showed that detoxification can be achieved either by treating the thin slices with low salt concentration and washing with water for a long period of time or by treating the thin slices with a high salt concentration followed by a shorter washing period.
Substitution of corn starch with yam flour in meat loaf formulation resulted in lower cooking losses and volume of drippings. Sensory evaluation of the meat loaf showed an improvement in crumbliness, juiciness and general acceptability.

Keywords : Binder. Detoxification. Dioscorine. Nami or kot. Wild yam.

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