To provide a technology capable of controlling a fertilization amount inexpensively.SOLUTION: A controller 100 for controlling an active farm machine for fertilizing an agricultural product, while moving on a field, includes a growth data reception part 104 obtained by sensing a growth state of the agricultural product at each part on the field, a fertilization amount value calculation part 107 for determining the fertilization amount based on the growth data, and a speed signal generation part 109 for generating a speed signal for allowing travel at the speed corresponding to a difference of the fertilization amount to each part on the field.SELECTED DRAWING: Figure 4
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