Pedo-Transfer Function for Saturated Hydraulic Conductivity of Paddy Soils

Soil 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

Paddy Field Zone Delineation Using Apparent Electrical Conductivity and its Relationship to the Chemical and Physical Properties of Soil

Spatial 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

Yield and yield components of sweet corn (Zea Mays L) grown under different tillage methods.

Field experiments were conducted to investigate the effects of three tillage systems on sweetcorn yield and selected yield components

Simulation of flood risk area in Kelantan watershed, Malaysia using numerical model

Flood 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

Rainfall trends in the Niger-South Basin, Nigeria, 1948-2008

Understanding rainfall trend can be a first step in the planning and management of water resources especially at the basin scale. In this study, standard tests are used to examine rainfall trends based on monthly, seasonal and mean annual series at the Niger-South Basin, Nigeria, between 1948 and 2008. Rainfall variability index showed that the decade 2000s was the driest (-2.1), while 1950s was the wettest (+0.8), with the decade 1980s being the driest in the second half of the last century, whereas the year 1983 was the driest throughout the series. Over the entire basin, rainfall variability was generally low, but higher intra-monthly than inter-annually. Annual rainfall was dominated by August, contributing about 15%, while December contributed the least (0.7%). On a seasonal scale, July-August-September (JJA) contributed over 40% of the annual rainfall, while rainfall was lowest during December-January- February (DJF) (4.5%). The entire basin displayed negative trends but only 15% indicated significant changes (a<0.1), while the magnitudes of change varied between -3.75 and -0.25 mm/yr. Similarly, only JJA exhibited insignificant upward trend, while the rest showed negative trends. About eight months of the year showed reducing trends, but only January trend was significant. Annual downward trend was generally observed in the series. The trend during 1948-1977 was negative, but it was positive for the 1978-2008 period. Hence, water resources management planning may require construction of water storage facilities to reduce summer flooding and prevent possible future water scarcity in the basin

Evaluation of SPAD Chlorophyll Meter in Two Different Rice Growth Stages and its Temporal Variability

Recently, agriculture production systems have benefited from incorporation of technological advances primarily developed for other industries. Site-specific crop management, well-established in some developed countries, is now being considered in other places such as Malaysia. The application of site-specific management principles and techniques to diverse crops and small-scale farming systems in Malaysia will present new challenges. Describing within-field variability in typical Malaysian production settings is a fundamental first step toward determining the size of management zones and the interrelationships between limiting factors, for establishment of site-specific management strategies. Measurements of rice (Oryza Sativa L.) SPAD readings was obtained in a Malaysian rice paddy field those were manually collected on 2 different rice growth stages(55 DAT and 80 DAT) and measured using a Minolta SPAD 502. Analysis of variance, variogram and kriging were conducted to determine the variability of the measured parameter. Finally, SPAD reading maps were created on the interpretation of the data was investigated

Application of geographical information system for farm mechanization education and training

Precision farming is managing each crop production input such as fertilizer, water, lime, herbicide, insecticide and seed on a site-specific basis to reduce waste, increase profit and maintain the quality of the environment. Without some remarkable enabling assisting technologies, the individual treatment of each plant is impossible and the concept of precision farming would not be feasible. Based on the trip, we can gain more information about the new technology that applies nowadays in agriculture. By using remote sensing that transmitted data from GPS, we can used to determination of generic object type, character and property as well as it’s abstract meaning. Besides, the application of remote sensing has been used in soil electrical conductivity sensor which used for show the variability of soil properties in detail and rapidly using simple equipment with less cost and labor force. Action maps will then be produced for farmers to apply fertilizers at different rates according to the delineated zones

Dam breach parameters and their influence on flood hydrographs for Mosul dam

Dams breach geometry prediction is crucial in dam break studies. The characteristics of flood hydrographs resulting from a dam breach essentially depend on the breach geometry and the required time for breach formation. To investigate the impact of breach parameters on maximum breaching outflows, five breach prediction approaches were implemented to calculate the flood hydrographs using HEC-RAS model, for Mosul dam. Numerous reservoir water levels for each approach were considered. Sensitivity analysis was carried out to evaluate the effect of each parameter on the resulting flood hydrographs. The time and value of peak discharge for each scenario were analysed and discussed. Results show that the most suitable method for estimating breach parameters for Mosul dam was the Froehlich approach. Furthermore, the sensitivity analysis shows that the breach side slope does not affect the peak discharge time and has a minor influence on peak outflow values. Meanwhile, the required time for the breach to develop was highly sensitive to both peak discharge and peak discharge time

The effect of pipe collectors in reducing the drainage coefficient rate

A high groundwater table and soil salinity, especially in arid regions, often cause serious problems for agriculture. In irrigated areas the subsurface drainage can be an effective technique to lower the depth of the groundwater table and reduce soil salinity. In drainage systems, lateral pipes are designed to collect the free water from soil and convey it into collectors. In other words, collectors are commonly designed to convey drainage water from laterals downstream, while the laterals play an additional role in removing excess water from irrigated land. The present research was conducted to investigate the effects of collectors in discharging excess water from soil using a laboratory-tank model. The results indicated that on average 24% of drainage water was directly discharged through the collector pipe when the hydraulic gradient of the flow was sloped toward the collector pipe. Hence, it was concluded that, with proper monitoring, collectors were capable of reducing the drainage coefficient from an average of 32.5 to 24.5 mm/day, while drain spacing of the laterals can increase the results by about 15% in comparison with the present situation