Ramanathan Sri Ranjan

Analysis of the petroleum components benzene, toluene, ethyl benzene and the xylenes in water by commercially available solid-phase microextraction and carbon-layer open tubular capillary column gas chromatography

Extraction of the petroleum components benzene, toluene, ethyl benzene and the xylenes (BTEX) from water is described using a commercially available poly(dimethylsiloxane) solid-phase microextraction fibre assembly with separation and quantification by carbon-layer open tubular capillary column gas chromatography and flame ionization detection. All components of BTEX are resolved. No cryofocussing is required.

Assessment of potential nutrient build-up around beef cattle production areas using electromagnetic induction

Electromagnetic induction (EMI) has been used to map soil properties such as salinity and water content. The objective of this research is to use EMI to map the potential distribution of nutrients around beef cattle pens and to relate this distribution to major physiographic field features. Beef cattle farms in different physiographic locations were surveyed in Manitoba, Canada, using an EM-38 conductivity meter georeferenced with a GPS receiver. Samples were collected using a response surface design and analysed for electrical conductivity (EC e), which was used as a proxy for determining potential build-up of nutrients. Multiple linear regression models (MLR) were used for calibration of the EM readings. The results showed that areas 1 through 4 had EC e≤3.5 dS m −1, but areas 5 and 6 exceeded this concentration and reached maximum values of 5.5 and 7.0 dS m−1, respectively. Higher values in area 6 were probably due to the presence of a rocky layer at 0.3 m depth, leaving a thin soil layer to accumulate the nutrients. Micro-depressions played a major role in salt accumulation, with the depressions corresponding to higher values of EC e. The presence of features such as drainage ditches and compacted soils beneath roads strongly affected the direction of the plumes. Based on these results, the location of the pens on high elevations and the provision to collect the run-off from the pens were identified as good design criteria. Highly permeable soils may require a low permeability liner to capture the deep percolation and redirect it towards a collection area.

Water Redistribution within the Potato Root Zone Following Irrigation

Monitoring crop water uptake and soil water movement within the root zone is critical for designing drainage systems. The objective of this study was to monitor the water movement within the root zone after the soil was fully saturated by irrigation. This experiment was conducted in Winkler, Manitoba, in a potato field instrumented with 15 Time Domain Reflectometry (TDR) miniprobes embedded in a vertical plane within the root zone for each replicate. The TDR miniprobes were installed at five different depths (0.1, 0.2, 0.4, 0.6, and 0.8 m) and at three different radial distances (0.15, 0.3, 0.45 m) from the base of the potato plant. Three such replicates of TDR probes were installed at vertical planes located one meter apart. A 5 m by 5 m area was blocked off, and 50 mm depth of water was applied to bring the soil to saturation within this area. The initial water content measurement prior to this irrigation event and at periodic intervals thereafter was carried out over a four-day period. In general, the volumetric water content showed an increasing trend with depth during the four-day period. However, with time, the water content decreased in every layer except the deepest layer indicating upward movement of water from below the root zone. The results also showed that moisture depletion in the upper layers of soil was replenished overnight. The overnight increase in water content within the root zone can be attributed to capillary rise of water from below the root zone as well as hydraulic lift caused by the potato plants. Hydraulic lift is a phenomenon in which the plant roots act as a conduit, for water transport from deeper layers of soil to the drier shallower layers within the rootzone. This process is enhanced further in the absence of transpiration during the night. This paper presents evidence of this phenomenon in potato plants.

ASSESSMENT OF ROOTZONE WATER REDISTRIBUTION IN CORN FOLLOWING IRRIGATION

An understanding of the water redistribution pattern within the corn rootzone will help design better irrigation and drainage systems. The objective of this research was to use time-domain reflectometry (TDR) miniprobes to measure water content within the rootzone of corn at different locations within the rootzone as a function of time. Forty-five TDR miniprobes were installed, in three vertical planes, for measuring volumetric water content and salinity within the rootzone of a corn field located in Winkler, Manitoba. The probes were inserted at 0.1, 0.2, 0.4, 0.6, and 0.8 m depths from the ground surface and at 0.12, 0.24, and 0.36 m radial distances from the base of the corn plant. The soil was thoroughly wetted by applying 50 mm of water within the experimental site. The volumetric water content was measured before and at periodic intervals after the irrigation event. The evening following the irrigation event showed an increase in water content within the entire soil profile. The water content started to decline as the days progressed. However, during the mornings, the soil within the root zone seemed to show an increase in water content when compared to the previous afternoon. An examination of the water content distribution within the root zone indicated an upward migration of water from soil layers located below 0.8 m.