Going Green: Organic Fertilizer
“Two thoroughbred horses.”
That is how Jack Gurley quickly answers the question of what he uses to fertilize Calvert’s Gift, his organic farm in Sparks, Maryland. Livestock of all kinds comes in handy for their useful waste, but organic growers can also choose among several other options for fertilization, notably compost and “green manure.” A multifaceted approach that combines several amendments usually proves most effective.
“The best soil management practices are to add compost regularly, grow cover crops and green manures, and apply organic granular fertilizer at every crop cycle,” say Daron Joffe, or “Farmer D,” an Atlanta-based developer of compost, raised beds and other products for national retailers, including Williams-Sonoma. “Also, use mulch to help seal in the fertilizer, moisture and organic matter to keep soil hydrated.”
Compost is a combination of wetted matter such as leaves and food that, over time and with help from worms, fungi and bacteria, gets broken down into humus: “earth” or “ground” in Latin. The more microbial action fluffing up the soil, the better. In keeping with the full-circle spirit of organics, plants help other plants in various ways. “Green manure” crops, nutrient-rich plants that are grown just for the purpose of getting ploughed under and churned into the soil, usually include legumes for their nitrogen-fixing properties, as well as sorghum, millet and buckwheat.
“Nothing gets wasted on an organic farm because we compost and use everything at hand,” says Sharon Rose Mauney, as she shoos some speckled guinea fowl out of her way at LoganBerry Heritage Farm, a Georgia enterprise known for 14 varieties of garlic. “Our sorghum squeezings go into the garlic, and we collect rainwater off the barn for this 450-gallon drum container to mix our own ‘teas,’ like tinctures for the earth. I look for materials heavy in silica, a building block for all tissues – many people don’t realize stinging nettles are a great source, even though they’re hard to collect -- and I mix in kelp and hydrolyzed fish protein for amino acids.”
Notes Joffe, “Liquid fertilizers and compost teas should be applied both to the root zone and the underside of leaves for best results.”
The “big three” minerals in most fertilizers are nitrogen (promotes leaves and vegetation), phosphorus (boosts roots and shoots), and potassium (helps with fruits, berries, and flowers). These “NPK” bags are commonly designated as “10-10-10” to denote the balance of each mineral, and you can supplement one of them for the desired effect.
“We use wood ash on our tomatoes because it’s high in potassium to build bigger tomatoes – if we used more nitrogen, we’d get more bushiness on them,” says Janisse Ray, a proprietor of Red Earth Farm in Georgia and the author of The Seed Underground: A Growing Revolution to Save Food.
Just as plants collaborate, growers often help each other, too, in the sort of symbiotic exchange that characterizes organic gardening.
“If you don’t have animals, scout your area for nearby chicken or turkey farms, where farmers are looking to get rid of their manures, and many will give it away and even truck it to you,” Gurley says. “Mushrooms make some of the best fertilizer. They have the most nutrients you need, they’re potent, and they last a long time – many organic fertilizers aren’t effective after 20 days or so, but spent mushroom compost sticks around.”