Diatomaceous Earth is an organic anti-caking agent and made from fossilized remains of aquatic organisms and is often used for lawn & garden applications. These organisms are called diatoms. The remains of diatoms are made from an all natural silica substance. Silica makes up, on average, 26% of Earth's crust. Diatomaceous Earth reacts with oxygen and water to create silicon dioxide. Since our Diatomaceous Earth is food graded, it can be used as an anti-caking agent to repel moisture in fertilizer in your garden. As with any powdery substance, you should not breath in Diatomaceous Earth as it can irritate the nasal passages, as well as eyes if direct contact is made. Diatomceous Earth comes in a 1LB resealable zipper bag for simple storage and re-usability.