DEVELOPMENT AND TESTING OF A CAPACITIVE DIGITAL SOIL MOISTURE METRE

This paper presents a low cost, simple digital soil moisture meter, working on the principle of dielectric. A digital soil moisture meter using the NE555 timer and micro controller as a major electronic component was developed and tested, which display its output in a range of 0.0 to 99% on the 7-segment displayed unit. The digital soil moisture meter developed was compared with gravimetric method for soil moisture determination on fifteen soil samples added different level of water during calibration process. The results revealed a relatively linear relationship between the moisture content process and the digital soil moisture meter. The regression coefficient (R2) of the digital soil moisture meter calibration was 0.984. Twenty soil samples were used in validation of the calibrated digital soil moisture meter. The regression coefficient (R2) was found to be 0.964, showing validity of the developed digital soil moisture meter. The developed meter provided up to 96% accuracy in estimating the value of the soil moisture content. The results showed that the developed digital soil moisture meter is more reliable, sensitive, precise and easy to use. http://dx.doi.org/10.4314/njt.v35i3.3

Assessment of the effect of cement industry effluent discharge on water quality of Ngo River in Benue, Nigeria

Ngo River in Gboko, Benue State, Nigeria which serves as a source of water for domestic and agricultural purposes for the agrarian community receives effluent from Dangote Cement factory. Physicochemical analysis of the effluent outfall and water samples collected along 15 km of the river stretch were carried out in dry and wet seasons respectively. The results obtained were compared to FEPA, WHO and NESREA Standards. For effluent outfall, Temperature, TDS, pH, EC, BOD, COD, sulphate and chloride, total hardness, calcium and magnesium, were found to be within the FEPA standards, while TSS, turbidity, and nitrate, were above the standards. Along 15 km study reach, mean temperature range of 32.4oC to 29.0oC, a TSS of 224 mg/l to 218 mg/l, a turbidity of 45 NTU to 42 NTU, and DO of 1.6 mg/l to 1.2 mg/l were obtain during the dry season, while mean temperature range of 36.8oC to 36.6oC, a TSS of 255 mg/l to 252 mg/l, turbidity of 176 NTU to 168 NTU, and DO 2.8 mg/l to 2. 6 mg/l were obtained during the wet seasons. These results were above WHO and NESREA temperature (25oC drinking water), TSS (30 mg/l domestic and 100 mg/l agriculture) water use, 5 NTU turbidity, and 5mg/l to 7.5mg/l DO standards. The effluent is relatively treated and effects such as aquatic depletion in the environment, decreased soil pore size and decreased permeability in the use of the water for irrigation, and water related diseases are not ruled out. Keywords: Cement industry, Effluent discharge, Water quality, Ngo River

Water Quality Evaluation of Spring Waters in Nsukka, Nigeria

Water qualities of springs in their natural state are supposed to be clean and potable. Although, water quality is not a static condition it depends on the local geology and ecosystem, as well as human activities such as sewage dispersion, industrial pollution, use of water bodies as a heat sink, and overuse. The activities on land use around the water sources can increase the level and number of contaminants if not properly used. This study evaluates the water quality of four spring waters (Asho, Ajie, Iyi-Nsukka and Ikwoka-Obimo) in Nsukka, Enugu state Nigeria to ascertain their suitability for drinking since they are consumed directly without treatment. Water samples were collected from these four springs and analyzed accordingly. The physical, chemical and bacteriological tests were carried out on the water samples with appropriate equipment. After analyzing the samples, it was found that some of the water parameters tested were within WHO/NIS standard and some were outside the range provided by WHO/NIS standard. Among the parameters tested that falls outside the range provided by WHO/NIS standard that has significant health implication are coliform and E. coli. It was found that there is high concentration of coliforms especially at Ajie and Iyi - Nsukka springs with 150MPN and 280MPN per 100ml respectively. Ajie and Iyi-Nsukka springs also have E. coli of 3MPN/100ml each while Asho and Ikwoka-Obimo springs have <3MPN/100ml. The contaminations is as a result of indiscriminate dumping of refuse, defecation around the water sources especially at the uphill side of these spring and the agricultural activities. Base on the findings, the water from these four springs is not safe for drinking without treatment

Development and testing of a capacitive digital soil moisture sensor with printed circuit board as a probe

The quantity and quality of water present in the soil determine to a greater extent the performance of agricultural crops. Real-time determination of moisture content has a greater advantage over the traditional gravimetric method of determining soil moisture content. Thus, this work was based on the design and construction of a cost effective digital capacitive soil moisture sensor for real-time measurement. The moisture sensors comprised four integrated units namely: power supply unit with a 9V DC battery as a power source, sensor unit with a locally sourced Printed Circuit Board (PCB) as the single sensing probe, control unit made up of PIC16f877 microcontroller programmed with a C language and the C source code compiled in Corporate Computer Services Compiler (CSS C) compiler development environment, and a 16x2 display unit which displays the readings in percentage moisture content (%MC) and capacitance (μF) of the soil obtained from the sensor on its screen. Standard gravimetric moisture content was carried out to get the calibration factor which was used to calibrate the sensor for reliability. The validation was done by taking the reprogrammed (calibrated) sensor to the field for further measurement, after which soil samples were collected for further gravimetric analysis. A regression equation was obtained by plotting the moisture content obtained from gravimetric method (%MCG) against that from sensor reading (%MCS) with a high degree correlation coefficient (R2) of 0.998. The developed capacitive soil moisture sensor is cheap, portable, reliable and easy to use even by local farmers. Keywords: Calibration, Capacitive sensor, Printed circuit board, Soil moisture content, Validation