Development of Tensio-Emitter- A Soil Moisture Tension Controlled Emitter

Abstract

Timely application of irrigation water in precise amounts increases crop yield due to decreased
moisture stress to plants and loss of water through percolation and subsequent nutrient leaching. Many
times, automatic scheduling of irrigation is desired as it ensures timely and precise application and reduced
labour cost. Automatic scheduling of irrigation usually involves sophisticated instrumentation which is
expensive and requires external power. Irrigation can be scheduled by measuring the moisture tension in
the soil which is an indicator the amount of water available to the crop. A system which utilizes the sensed
moisture tension to directly control the water applied without using an external power source is desired.
This study was carried out to develop a simple and cost effective soil moisture tension controlled irrigation
emitter that works without any external power sources. The developed Tensio-Emitter consists of a porous
cup and emitter assembly and it functions on the same principle as that of a tensiometer. The TensioEmitter can be calibrated by adjusting the conical valve and the top assembly, so that water flows through
the emitter only when the soil becomes dry and closes when the soil receives enough water. The tensioemitter was successfully developed, fabricated and calibrated for use in potted plants