The monitor system for an anhydrous ammonia fertilizer injection system includes a manifold with a plurality of discharge lines connected to soil engaging knives. A temperature sensor is mounted in each discharge line. The temperature of fertilizer in each discharge line is measures and transmitted to a microprocessor in a console. The temperature in a discharge line is compared with the average temperature in the other discharge lines. This comparison is made for each discharge line connected to a manifold to determine the temperature variations. The variations are compared to a temperature variation number provided by the operator. If an excessive variation occurs a warning is provided. A console screen graph shows which discharge line needs inspection.
