FABRICATION OF LOW COST SOIL MOISTURE SENSOR FOR IRRIGATION WATER MANAGEMENT

The study was aimed at fabricating a low cost soil moisture sensor which can help in optimizing the use of water. The sensor was made using gypsum blocks. The moisture content in the soil was indicated by an LED attached to an LM339 comparator circuit which glows when the moisture level in the soil falls below an optimum value. A comparative study on the effect of chemical and organic fertilizer on moisture retention capacity of soil was made. Soil samples for the study were collected from the main campus and satellite campus of Lady Doak College, Madurai, India. The soil and water from both the campuses have been tested for pH, Electrical Conductivity, TDS, sodicity. The NPK levels of soil were also determined before and after the addition of organic and chemical fertilizers. It has been found that the nutrient content, sodicity and hence the water holding capacity of the soil collected from the satellite campus was greater than that collected from the main campus. The developed sensor was found to be effective in determining the moisture content of the soil.