Using animal poop in agricultural pursuits is nothing new. We’ve used nutrient-rich dookie on plants for a long time. Bird and bat excrement, or guano, is particularly rich in nitrogen, phosphorus, and potassium, and before the development of synthetic fertilizers, a significant economic driver of imperialism. So critical was seabird droppings that in 1864, Spain occupied the guano-rich Chincha Islands of newly independent Peru, igniting a war that would eventually involve neighbors Bolivia, Chile, and Ecuador.
Animal manure is still harvested and used over synthetic fertilizer, particularly as interest in organic produce has increased. With dairy cows, it also prevents the same chemicals plants crave, especially nitrogen and phosphorus, from running off into waterways, where an increase in these substances can cause harm to aquatic ecosystems and harm water supplies.