A Balance Micro Lysimeter as a Control for An Irrigation System.

Introduction. Automatic irrigation systems usually use timers that star and stop pumps or open and close valves at determined times. Soil humidity sensors are also used to star or stop pumps accordingly to their calibration. Although it is possible to control soil humidity of a crop using these methods, they do not integrate plant development and growth and natural evaporation through the plant cycle. Objectives. To design and built a balance micro lysimeter as a control element of a irrigation system. To probe that natural evaporation can be used to control an irrigation system. Materials and methods. A balance micro lysimeter was designed to control the irrigation system’s pumps and valves. The micro lysimeter is constructed as two metal boxes, the small one inside the big one. The small one is holded by a spring mechanism and contains the soil. As the soil is at field capacity the small box moves down to a minimum and as it looses water it goes up until a chosen maximum. These movements close or open an electric circuit starting or stopping pumps or valves. An irrigated bean crop was established using the micro lysimeter as a control for watering it. Results. The micro lysimeter controlled the irrigation system acceptable. The inside and outside irrigated plants grew well. Conclusion. A balance micro lysimeter can be used to control an irrigation system.