Geostatistical analysis in paddy field data and implications for management

Soil properties and yield were recorded in grid-spacing in a West Malaysia paddy field for the year 2000. Geostatistical analysis showed that soil properties and yield were notably correlated in space, and the range of spatially dependent yield was shorter than the soil properties. Co-kriging was used to estimate spatial pattern of yield with surrogate data (soil properties) was not successful for this field. The spatial yield map illustrated that the middle portion of the plot has lower yield (5t/ha)

Mapping the Variability of Soil Texture-Based on Vis-NIR Proximal Sensing

Soil texture is one of the soil properties influencing most physical, chemical, and biological soil processes.  Information on soil texture is important to support the agronomic decisions for farm management. The problem is how to provide reliable, fast and inexpensive information of soil texture in numerous soil samples and repeated measurement. The objective of this research was to generate the soil texture map based on laboratory Vis-NIR (Visible - Near Infra-Red) spectroscopy and inverse distance weighted (IDW) interpolation method. An ASD Fieldspec 3 with a spectral range from 350 nm to 2500 nm was used to measure the soil reflectance. Pipette method was used to measure the silt, clay and sand fractions. The partial least square regression (PLSR) was performed to establish the prediction model of soil texture. The predicted values were mapped and showing the information of spatial and temporal variability of soil texture. Keywords: Vis-NIR, spectroscopy, soil texture, PLSR, ID

Intelligent control for capillary irrigation system for water saving cultivation

Subsurface micro irrigation techniques such as capillary irrigation has long been proven to provide higher water saving for cultivation. Advancement of the capillary irrigation system has been made by using a high capillarity fibrous medium to transfer water directly to the rooting zone of plant. Wicking of water through the fibrous medium depends on the distance from a water source which known as water supply depth. The irrigation system is being managed by manipulating the water supply depth. However it is difficult to determine the optimum depth due to the dynamic water requirement which depends on the plant growth stage and climatic change. In this study an adaptive method was introduced to manage the irrigation system based on water balance and energy balance model. Using the estimated data the optimum depth was determined by using fuzzy expert system. An experimental set-up was built using the fibrous-capillary irrigation system that allowed the change of water supply depth in real time. The optimum water supply depth obtained based on the adaptive method was analyzed based on water usage and plant yield which showed significant amount of water saving. The results suggested the feasibility of the water and energy control model as an irrigation scheduling index for the fibrous-capillary irrigation system

Capillary flow responses in a soil-plant system for modified subsurface precision irrigation

Water movement in a soil-plant system was evaluated based on capillary flow in a modified subsurface irrigation system that incorporates a plant-water measuring device. Water from a reservoir tank located underneath the plant pot was supplied to the root zone through a fibrous medium. Evapotranspiration was measured from the water uptake and evaluations were performed based on soil moisture distribution and mass balance. Potential evapotranspiration was used as a reference for the plant-water uptake. Data were obtained from a test plant provided with the modified subsurface irrigation system. The plant was grown in a phytotron under controlled air temperature and humidity, and a comparison was made for different levels of soil moisture condition. The experimental results confirmed the operational efficiency of the modified subsurface irrigation system for precision irrigation