In the process, it also leaves behind castings that, according to the book Step by Step Organic Vegetable Gardening, are “five times as rich in nitrogen, phosphorus, and potassium [as] the surrounding soil. ”
Dalam proses itu, cacing tanah juga meninggalkan kotoran yang, menurut buku Step by Step Organic Vegetable Gardening, ” lima kali lebih kaya akan nitrogen, fosfor, dan potasium daripada tanah di sekitarnya ”.