Real-Time Measurement of NO3− and NH4+ Leaching from Plant Nursery Pots

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Concerns relating to pollution from nitrogen fertilizers leaching into ground water are increasing. This is especially important in southern Florida because the pollution threatens fragile ecosystems in Biscayne Bay, and the two National Parks that abut agricultural areas. The current research is focused on the development of an automatic system which can monitor and leaching from plant nursery pots. and electrodes and a load cell were used for real-time measurements of , , and leachate volume. The leachate was directed to pass the sensing areas of , reference, pH, and electrodes. It was collected and weighed in a container placed on a load cell. The analog signals from the electrodes and load cell were digitized through data acquisition technology using a 16-bit A/D converter and a self-developed software program. With this system the volume of the leachate and concentrations of and in the leachate were determined in situ. Based on this design, the dynamics of and leaching from pots can be observed. This system can be used to 1) determine soil (or media) holding capacity of and , 2) evaluate the effects of nitrogen fertilizer formulations on water quality, 3) develop best management practices of nitrogen application in containerized plant production, and 4) determine the soil-holding capacity to optimize the use of water. The advantages of the developed system are 1) low labor cost for sample collection and analysis and 2) high measurement resolution resulting from a minimization errors that occur during sampling and other manual operations.