Issue link: http://read.uberflip.com/i/1073364
A closer look at the science of organic fertilizers Give and Take Diggin' In Diggin' In "Feed the soil to feed the plant" is a guiding precept of organic soil fertility that I hear repeated from well-intentioned people who have rarely given it serious consideration. Practices to increase soil organic matter, biological activity and plant nutrient availability are all desirable goals, but let's take a closer look at organic fertilizers and see how they can best fit into a sustainable crop production system. Over the past few decades, the principles of organic farming have been accepted into mainstream research, extension and university classes. While there are commendable outcomes with organic practices, the strict boundaries and prohibitions can cause people to overlook the underlying assumptions that do not always align with good science. Supplying organically grown crops with nutrients is commonly accomplished by stripping nutrients off a large area of land and then applying them to a much smaller field. For example, when chickens are fed corn and soybeans harvested from a farmer's field, nutrients leave the soil when the grain is harvested (and diminishing the nutrient supply for subsequent crops). As the chicks eat the grain and grow into full-size broilers, they produce nutrient-rich manure. The poultry farmer then collects the manure and prepares it for sale to an organic FERTILIZERS | By Rob Mikkelsen, International Plant Nutrition Institute 58 POTATO GROWER | FEBRUARY 2019 "The inevitable result of farming is always to diminish natural fertility because portions of the total supply of plant nutrients… are removed." —G.W. Cooke, 1967