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Paddy Field Zone Delineation Using Apparent Electrical Conductivity and its Relationship to the Chemical and Physical Properties of Soil
Get PDFSpatial variability and temporal variability of soil chemical and physical properties
within a field is unavoidable. Meanwhile, laboratory soil test is usually time
consuming and laborious. To satisfy the concept of precision farming, rapid and
intensive soil sampling is necessary for describing the uncertainty within a field.
Apparent or bulk soil electrical conductivity (EC,) technique for describing soil
spatial variability is widely used. A sensor known as VerisEC can measure the
average EC, of 0-30 cm (shallow EC,) and 0-90 cm (deep EC,) depths and locate its
position by Differential Global Positioning System (DGPS) at every second. EC,
includes soil salinity and soil texture. Soil texture has high correlation with soil
cation exchange capacity (CEC) hence, soil nutrient contents. The main purpose of
this study was to generate variability map of soil EC, within rice cultivation areas
using VerisEC sensor for three seasons. The EC, values were then compared to some
soil chemical and physical properties namely pH, EC, OM, OC, total S, total N,
available P, CEC, Ca, Mg, K, Na, Al, Fe, total cation, BS, ESP, dry bulk density,
moisture content, clay, silt, fine sand, coarse sand and sand, within classes after
delineation. The study site was 145 ha paddy fields at Block C, Sawah Sempadan in the Tanjong Karang Rice Irrigation Scheme, Malaysia. The sensor was pulled by a
tractor in a U-shape pattern between the field drains (speed = 15 km h-'). Disturbed
and undisturbed of 236 sampling points were collected and recorded their positions
by GPS (Trimble GeoExplorer3). Soil properties and EC, data were mapped using
kriging technique on GS+ and ArcGIS. SPSS and SAS were used for their statistical
analysis. The study showed that the EC sensor can determine soil spatial and
temporal variability, where it can acquire the soil information quickly with less
labour. Most of the soil properties and EC, changed from one season to other
seasons, except total N. Much of the soil properties had the same mean values for
seasons 1 and 3 such as K, moisture content, silt and coarse sand. Spatial variability
of shallow and deep EC, had the same pattern for different seasons even though the
mean values were different. Deep EC, showed the pattern of former canal routes
clearly as continuous lines about 45 m wide at the northern and central parts of the
study area. Low Na in zone 1 delineated by deep EC, may be due to deep soil profile
to reach the parent material of marine alluvial, where it was a former water route.
High fine sand and sand in zone 1 were found for all the seasons. The models of soil
properties estimation based on EC, varied spatially and temporally from season to
season and even from zone to zone. Most of them can be estimated better by deep
EC, except, soil K and ESP. The selected models showed that the highest significant
R* was found in fine sand and sand models with the consistency of the model
throughout the study seasons. The relationship between yield and deep EC, was non
significant for all the season
Pedo-Transfer Function for Saturated Hydraulic Conductivity of Paddy Soils
Get PDFSoil saturated hydraulic conductivity (Ks) is an important soil physical property, especially for determining infiltration rate, irrigation practice, drainage design, run off, deep percolation, groundwater recharge and in simulating leaching and other agricultural and hydrological processes. Several laboratory and field methods can be used to determine Ks. Unfortunately, laboratory and field determinations are usually time consuming, expensive and labour intensive. Deep percolation (DP) is the vertical movement of water beyond the root zone to the water table. It is an important component in the calculation of irrigation requirement and irrigation efficiency. Pedo-transfer functions (PTF) serve to translate the basic
information found in the soil survey into a form useful for broader applications through empirical regression-of functional relationships, such as simulation modelling. PTFs have not been applied to paddy soils in the study area. A lot of field measurements will require high labour input hence high cost. This study attempts to simplify the determination of Ks. The main objectives of this study were to seek a simplified method for determining Ks values based on PTF and estimate DP losses in paddy field based on the dominant Ks of the soil profile. Soil samples were collected randomly depending on the soil series within the
2,300 ha Sawah sempadan compartment rice cultivation area. There are five dominant soil series namely, Jawa (Sulfic Tropaquept), Sedu (Typic Suljaquept), Sempadan (Sulfic
Tropaquept), Karang (Typic Sulfaquept) and Telok (Typic Suljaquept). Both field work and laboratory work were carried out. The samples were then analysed for the following properties: moisture content in volume basis, bulk density, particle size distribution, organic carbon, pH, electrical conductivity, particle density and moisture content at 33 kPa. The parameters were then used as inputs for developing a Ks model by using SAS (Statistical Analysis System) and SPSS (Statistical Package for Social Science) tools. The Ks values were obtained by using falling head method. Microlysimeter method was adopted to measure the DP loss. The results of the study showed that the high spatial variability of the saturated hydraulic conductivity in the paddy was high. The best regression model for estimating Ks was based on eight soil properties. Five of the eight parameters are the textural attributes, namely clay (C), medium sand (MS), very fine sand (VFS), fine sand (FS) and silt (Si). Others are bulk density (Db), organic carbon (Oe) and moisture content at 33 kPa (8113). The best model fo und from this study was Ks=e(l285-0967 (Dt 8 36x10· 2 (C)+8 55x10 - 2 (OC}-O 134 (MS}-O 943 (Ina 1I3}-O 349 (InVFS)+O 413 (InF5)-2 145 (In51)-0 411 (FS)] (R2 = 0.49). The results of DP study showed that DP loss could be estimated by knowing the average values of Ks of the three layers (topsoil, hardpan and subsoil). DP loss is best related to Ks b y a power function, DP = 3.29 Ks042
(r = 0.60**). These models still need to be further calibrated or validated with other existing data as the input parameters in order to make it more useful
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Simulation of flood risk area in Kelantan watershed, Malaysia using numerical model
Get PDFFlood events have recently increased and caused extensive damages to the agricultural area and infrastructures, despite enormous efforts to decrease this hazard. Modeling of runoff can be a suitable approach to determine the effective factors in flooding, and to explore reasonable solution and thus to be able reduce hazard on watersheds. The current work attempted to derive basin and sub-basins, stream network, aspect, slop and all relevant physiographic parameters of Kelantan watershed in order to estimate depth of runoff using DEM data , satellite images and field study. In addition, the maximum rainfall intensity of all the meteorological stations were extracted and the interpolation of the values obtained, led to derive a contour map as rainfall intensity for the watershed. Soil Conservation Service (SCS) model was employed to calculate the surface flows, and to derive the flood hydrograph for all the sub-basins at the return periods of 5,10,25,50,100, considering to the Curve Number (CN) is a function of land use, soil, and primary moisture content. HEC-HMs model was calibrated for the study area using observed storm rainfall and recorded floods at the number of hydrometric stations. A good agreement was obtained between simulated and observed data with a correlation of 82%. Calibrated model was used to simulate depth of runoff in different return period that led to derive flood risk maps for Kelantan watershed. Results obtained revealed that flooding could be moderated and managed within a number of the sub - basins through implementing a technical scheme, depending on characteristic of the sub- basin, and its effect on the flood peak
Development of an early warning system for brown planthopper (BPH) (Nilaparvata lugens) in rice farming using multispectral remote sensing
Get PDFThe spread of rice pests such as BPH in tropical areas is one of the best-known yield lost factors. Remote sensing can support precision farming practices for determining the location of spreads and using pesticide in the right place. In a specifically conducive environment like high temperature and heavy rainfall, BPH population will increase. To address this issue, detection of sheath blight in rice farming was examined by using SPOT-5 images. Also, the extraction of weather data derived from Landsat images for comparing with the BPH infestation was undertaken. Results showed that all the indices that recognize infected plants are significant at α = 0.01. Examination of the association between the disease indices indicated that band 3 (near infrared) and band 4 (mid infrared) in SPOT-5 images have a relatively high correlation for detecting diseased part from healthy ones. The selected indices declared better association for detecting healthy plants from diseased ones. Image investigations revealed that BPH were existing at the higher limits of tolerable temperatures when in the form of nymphs. With the knowledge that the late growth stage of plants has more severe BPH attacks, the results stated that BPH outbreak is particularly obvious in the north-west corner and middle regions of the maps and it is more likely to happen in specified ranges of temperature and RH, i.e. 29 °C <T< 32 °C, and 88 % <RH< 93 %
Variations on the Author
Get PDF“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
Get PDFWe 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
Yield and yield components of sweet corn (Zea Mays L) grown under different tillage methods.
Get PDFField experiments were conducted to investigate the effects of three tillage systems on sweetcorn yield and selected yield components
Growth responses of two kenaf varieties (Hibiscus cannabinus L.) applied by different levels of potassium, boron and zinc
No full textThe aim of this study was to determine the effect of potassium, boron and zinc rates on the growth of kenaf. Seeds of two kenaf varieties namely; FHH 925 and 4383 variety were planted on 26 September 2013. Plant growth was determined for both varieties. The growth characteristics which consist of plant height, stem diameter and leaf number were measured every two weeks for five times consecutively. The best result was achieved for both characteristics; stem diameter and leaf number for FHH 925 variety when potassium and boron added at rates of 150 and 1.5 kg/ha, respectively except plant height was better when potassium was at the same rate while boron and zinc were controlled. The results showed a significant impression on the kenaf growth. It would be apposite to choose better varieties of kenaf for the production purpose with using better controlling of macro and micronutrients
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