The invention provides an automatic fertilizing device without an additional power source. The automatic fertilizing device comprises an
impeller, a feeding pump, a generator and a water-soluble
fertilizer liquid
barrel, wherein the
impeller is used for being arranged in an
irrigation pipeline; the generator is connected with the
impeller which drives the generator to work and generate
electricity; the feeding pump is connected with the output end of the generator, and an outlet of the feeding pump is used for being communicated with the
irrigation pipeline; and the water-soluble
fertilizer liquid
barrel is connected with an inlet of the feeding pump through a material conveying
pipe and is used for accommodating a liquid
fertilizer. According to the automatic fertilizing device provided by the invention, when liquid flows in the
irrigation pipeline, the impeller rotates to drive the generator to generate
electricity and supply power to the feeding pump, and the liquid fertilizer enters the irrigation pipeline from the feeding pump to be mixed with the liquid, so that crops are fertilized while being irrigated, namely, water and fertilizer integrated irrigation is realized, and the automatic fertilizing device is widely applicable to irrigation and fertilization in channel irrigation areas, realizes
automation of farmland irrigation and fertilization, and ensures uniform fertilization.