| ABSTRACT |
A fertigation system is defined as a combination of fertilizer solution and irrigation water directly applied to the crop root zone. The system (Figure 1) is necessary for crop production under a naturally ventilated tropical greenhouse, screenhouse or open field to supply a precise amount of water and fertilizer solution, reduce soil diseases, increase field efficiency, increase crop productivity and quality.
Evapotranspiration (ET) is the process of transpiration by plants combined with evaporation that occurs from plant and soil surfaces. Evapotranspiration based controllers can adjust the amount of nutrient solutions in response to plant needs. The ET controller will calculate the evapotranspiration rate of specific plants based on multiple climate monitoring systems and transfer the data to main controller using wireless or wired data communication to estimate the amount of nutrient solutions needed by each plant. The main controller receives feedback from the irrigated system and schedule or adjusts irrigation duration and/or frequency accordingly. It also calculated the amount of fertilizer needed based on nutrient monitoring system and planting season and automatically mixed and measures the calculated amount of fertilizers before pump the nutrient solution to irrigation system. Figure 2 shows the basic operation of the system.
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