1,720,956 research outputs found
Comparative Efficacy of Various Sources and Rates of Phosphate Rocks to Oil Palm Seedlings
Full text linkPhosphate Rocks (PR) from various geographical locations are being
imported into the Malaysian market mainly from Algeria, North Carolina
(USA), Tunisia, China etc. PR vary widely in their physical, chemical and
mineralogical properties. Consequently, the solubility and agronomic
effectiveness of PR sources also vary widely. In addition, the agronomic
effectiveness of PR depends on interactions between several factors, particularly
PR material characteristics, soil properties, crop characteristics, and environmental conditions. Hence, There is a need to evaluate the efficacy of
various sources of PR as phosphate source for plant growth. In \tiew of this, a
glasshouse experiment using oil palm seedlings and a laboratory incubation
experiment were used to evaluate the efficacies of these sources of PR The
study was undertaken with the following objectives :
1. to assess the solubility of PR in soil by various solubility tests.
2. to evaluate the dissolution of PR sources in an acid Malaysian soil, using
an incubation experiment
3. to determine the relative agronomic effectiveness of PRs to oil palm
seedlings in glasshouse experiment.
4. to characterize the immediate and residual availability of PR using the E-value
approach
Water dynamics and ground water quality assessment in an oil palm ecosystem
Full text linkOil palm crops have been estimated to use a lot of water for their growth and production. Hence, oil palm can cause a decline in the soil water table. In addition, oil palm also requires the use of fertilizers to maximize its growth and crop production, and this has led to detrimental effects on the ground water quality. Leaching causes a loss of nutrients as they are washed further downward into the soil apart from causing ground water pollution, eventually. Ground water contamination can cause serious problems to ground water as it is the main water source used by most people to meet their drinking water needs. Furthermore, there is still very little information about the sources of water uptake by oil palm although the information is important for water management system at oil palm plantations. Hence, there is a need to evaluate water use and water quality at oil palm plantations. This study was undertaken with the following objectives: i. To evaluate the impact of climatic factors on water table of an oil palm plantation and its surrounding region; ii. To investigate the impact of oil palm fertilization on ground water quality; iii. To identify water sources of oil palm; and iv. To evaluate a water table model for an oil palm plantation. The study on the dynamics of water table level at an oil palm plantation and its surrounding region was carried out by conducting a daily monitoring on water table level at Kabun – Aliantan (N: 0002.925’E: 100049.977’) watershed area in Tandun, Riau, Indonesia, from 2009 until 2011. Data analyses that were carried out included the correlation analysis on the water table level at each well point location with several climate elements in the same time period, and the correlation analysis on the changes on water table levels between the oil palm area and other locations during the same period. Besides, the study was also carried out to analyze the water system at a mature oil palm area, where an observation plot was built to measure the water balance in the area. The variables used to measure changes at the observation plot were precipitation, soil surface, evaporation, and runoff. Based on these variables, water infiltration was then determined.The results showed that the height of water table level in the oil palm plantation area is related to elements of water balance which include rainfall, interception, evapotranspiration, and surface runoff water. Data show that water table level that declined in the dry season period increased again during the rainy season, indicating that the decline in water table level was not permanent. Water table levels in the area surrounding the oil palm plantation also fluctuated based on the conditions of rainfall. The decline in water table level in the area surrounding the oil palm plantation did not correlate with the oil palm crop itself. However, the condition of the water table at any location in the oil palm plantation areas shows that there is a relationship between one location to another. Evaluations made based on the water table dynamics model fitted rather well the results of direct measurements, with coefficient of determination (R²) of 0.8138 or 81.38 %. The value of Root Mean Square Error (RMSE) between the model and direct measurement was 27.33 mm while the correlation coefficient between the model and direct measurement was 0.90. There is a relationship between water table level and oil palm productivity. Water table level at lag time of 8-9 months and 33-35 months before harvest affects oil palm productivity. Oil palm plantations need fertilizers for optimum growth and production. However, excessive use of fertilizers can lead to ground water contamination. Due to this, a study on the quality of ground water in an oil palm ecosystem had been conducted. It involved monitoring of 9-point monitor wells and measurements of runoff. The parameters analyzed in the water samples were pH, nitrate-N (NO3-N), nitrite-N (NO2- N), ammonium-N (NH4-N), phosphate (P), potassium (K), calcium (Ca), and magnesium (Mg). The findings of the study showed that the concentrations of pH, Nitrate-N (NO3 -), Nitrite-N (NO2 -), Ammonium-N (NH4 +), Phosphate (P), Potassium (K+), Calcium (Ca), and Magnesium (Mg) at the oil palm plantation did not exceed the contamination level for safe drinking water set by WHO. In general, the increased concentrations of pH, Nitrate-N (NO3 -), Nitrite-N (NO2 -), Ammonium-N (NH4 +), Phosphate (P), Potassium (K), Calcium (Ca), Magnesium (Mg) that occured after fertilizer application eventually decreased with time. This study clarified that fertilizer treatments in the oil palm plantation did not reduce the quality of ground water although data showed that the value of Ammonium-N (NH4 +) was high in the housing complex and exceeded the safe drinking water limit set by WHO. The study also aimed to determine the current water source absorbed by the roots of oil palm by using the deuterium (δD) and oxygen isotope (δ18 O) method. The signatures of deuterium and oxygen isotope in total rainfall, throughfall, runoff, measurement at 5 soil depths (20 cm, 50 cm, 100 cm, 150 cm, and 200 cm), and in the stems of oil palm. The results showed that the values of deuterium and oxygen isotope varied significantly. Based on the Least Significant Difference (LSD) test, no significant difference was found in the deuterium and oxygen isotope in the stem water samples and other samples. This experiment showed that oil palm absorbs a mixture of soil water of ground water, soil water, and precipitation from several soil layers. Similar isotope signatures were also obtained from water samples taken at the depth of 0-50 cm and in the stem water. This result is in accordance with the oil palm root system, i.e. the quarternary roots (0-50 cm) is the most active root of oil palm that absorbs nutrients, water, and oxygen. This indicates that oil palm possibly absorbs water more dominantly from the depth of 0-50 cm
DINAMIKA AIR DAN FASE-FASE PERKEMBANGAN PEMBUNGAAN PENENTU PRODUKTIVITAS KELAPA SAWIT
Full text linkTo identify flowering development phases that most determines oil palm yield in relation to water dynamics, a research had been conducted at Indonesian Oil Palm Research Institute (IOPRI) experimental garden in Tandun, Riau. The variables observed were water parameters including rainfall, groundwater level, soil water content, and the rate of increase in capillary water at 0 – 200 cm soil depth. Rrelationship between water parameters and oil palm yield was analyzed using correlation statistics and multiple linear regression models. Analysis of multiple linear models was performed using stepwise regression techniques to select the most powerful parameters determining the relationship between independent and non-independent variables. MATLAB R2017b software was used for data processing. The study showed that phases of flower bunch development at certain time prior physiological maturity determined monthly oil palm yield. Critical phases affected oil palm yield were formation of flower crown, sex differentiation, appearence of flower buds, and ripening of fruit bunches. Compared to other flower developmental phases, the phase of sex differentiation of flowers that occurred 20 months before the fruit bunches were physiologically mature was the most critical phase in determining monthly yield of oil palm.Untuk mengetahui fase-fase perkembangan pembungaan yang paling menentukan produktivitas kelapa sawit dalam kaitannya dengan dinamika air pada pertanaman kelapa sawit, maka dilakukan penelitian pada areal pertanaman kelapa sawit di kebun percobaan Pusat Penelitian Kelapa Sawit (PPKS), Tandun, Riau. Peubah yang diamati adalah parameter air meliputi curah hujan, muka air tanah, kadar air tanah, dan laju kenaikan air kapiler pada lapisan 0 – 200 cm. Hubungan peubah parameter air dan produktivitas kelapa sawit dianalisis dengan statistik korelasi dan model regresi linier ganda. Analisis model regresi linier ganda menggunakan teknik stepwise regression untuk memilih parameter yang paling kuat hubungannya antara peubah bebas dan tidak bebasnya. Pengolahan data dalam analisis korelasi dan model persamaan menggunakan piranti lunak MATLAB R2017b. Hasil penelitian menunjukkan produktivitas bulanan kelapa sawit ditentukan oleh fase-fase perkembangan tandan bunga yang terjadi beberapa waktu sebelum matang fisiologis. Fase-fase kritikal yang mempengaruhi produktivitas tersebut adalah pembentukan perhiasan bunga, diferensiasi jenis kelamin, pemunculan kuncup bunga, dan pematangan buah. Fase diferensiasi jenis kelamin bunga yang terjadi pada 20 bulan sebelum tandan buah matang fisiologis adalah fase yang paling kritikal dalam menentukan produktivitas bulanan kelapa sawit dibanding fase-fase perkembangan bunga yang lain
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Effect of Fertilizer Application on Groudwater Quality at an Oil Palm Plantation
Full text linkOil palm plantations need fertilizers for optimum growth and production. However, excessive use of fertilizers can lead to pollution of groundwater. For this reason, a study was carried out to investigategroundwater quality of an oil palm ecosystem, which involved the measurement of 9-point monitor wells and run-off. This research was conducted in Kabun-Aliantan (N: 0002.925’ E: 100049.977’). Tandun, Riau-Indonesia. The location points of the monitored wells in this study comprised a young oil palm area (P1), an adult oil palm area near Lau river (P2), a housing complex at oil palm plantation (P3), an adult oil palm area at Marihat, Block A (P4), a housing 1 at the sub-district town (P5), a housing 2 at the sub-district town (P6), a cocoa area (P7), a village housing (P8), at the side of Lau river (PR), and a run-off in a micro catchment (N: 00027.936’ E: 100049, 977’). The parameters analyzed in the water samples were pH, nitrate-N (NO3-N), nitrite-N (NO2-N), ammonium-N (NH4-N), phosphate (P), potassium (K), calcium (Ca) and magnesium (Mg).In general, pH, NO3-N, NO2-N, NH4-N, P, K, Ca and Mg increased after fertilizer application and decreased with time. All levels of parameters were lower than the WHO standard for drinking water. This study showed that the fertilizers on the oil palm plantation did not pollute the groundwater quality. However, groundwater pollution was found to be caused by residential wastes, such as the use of detergents and other human activities
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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