Various implementations of the present disclosure are directed systems and methods of preparing a fertilizer product from cactus. The method includes grinding cladodes of one or more cactus plants into ground cactus and selecting prickly pear fruits from the one or more cactus plants. The method further includes combining the ground cactus, the selected prickly pear fruits, water, and a ruminal fluid in a first container to form a mixture. The method further includes storing the mixture in the first container for a first time period such that the mixture reacts to form a digestate. The method further includes storing the digestate in the first container or a second container for a second time period such that the digestate forms the fertilizer product.