The invention relates to a method of extracting contents from sealed flexible containers using irrigation water, to a device for implementing same and to the container used. The inventive method essentially comprises the following steps: a) perforation of the container (1) with the closure of a container support (10); b) injection of irrigation water into the container (1) through the perforations thus produced; c) breakage of the container, by applying same against breaking means comprising projecting elements (16) that are disposed on the container support (10), such that the container (1) is subjected to the pressure of the irrigation water; and d) extraction of the soluble fertiliser (3) contained in the container (1) by means of the stream of irrigation water. The invention also relates to the device used to perform said method, comprising a container support (10) which is divided into a body (12) and a lid (13), perforation means in the form of points (15), water injection means, breaking means consisting of projections (16) which are disposed inside the container support (10) and means for opening and closing the container support (10). The container (1) used comprises a receptacle (2) which is closed with a cover (4) having a peripheral rim (7).