High in potassium are kelp (4-13 percent K), wood ash (3-7 percent K), granite meal (3-6 percent K) and greensand (5 percent K). Organic amendments highest in phosphorus include rock phosphate (20-33 percent P), bone meal (15-27 percent P) and colloidal phosphate (17-25 percent P). To boost the nitrogen content of your soils, apply nitrogen-rich urea (42-46 percent N), feathers (15 percent N), blood meal (12.5 percent N), dried blood (12 percent N). 'This equals about 8 pounds of this fertilizer applied to get one pound of nitrogen out there in the soil.'Д«lood meal (12.5-1.5-0.6) releases nutrients over a period of two to six weeks.Д«urned eggshells (0-.5-.3), fish emulsion (5-1-1) and urea (urine) (46-0-0) are the fastest-acting organic fertilizers, lasting only a couple of weeks. 'For example, using 12-11-2 fertilizer, if we knew we wanted to apply one pound of nitrogen, we would use 1/12th of 100 pounds,' he said. In simple terms, this means each 100-pound bag of the fertilizer would contain 12 pounds of nitrogen, 11 pounds phosphorus and two pounds nitrogen. 'For a fertilizer with an N-P-K ratio of 12-11-2, this means 12 percent is nitrogen, 11 percent is phosphorus and 2 percent is potassium. 'One of the most difficult things to determine for an organic gardener is how much organic fertilizer to use, say on 1,000 square feet of garden,' said Penhallegon. Penhallegon has collected information about the nitrogen (N), phosphorus (P) and potassium (K) content of many of the organic substances commonly used as fertilizer in Oregon. Fresh, non-composted manure can damage your plants as well, because some manure contains harmful amounts of salts. Since many chemical/inorganic fertilizers are concentrated and very soluble, itвЂ™s easier to apply too much and damage your plants. But they may cost more than chemical, or inorganic fertilizers, because they are less concentrated, supplying fewer nutrients pound for pound. Organics feed beneficial microbes, making the soil easier to work. They improve water movement into the soil and, in time, add structure to the soil. They donвЂ™t make a crust on the soil as inorganic fertilizers sometimes do. Many of these nutrients have to be converted into inorganic forms by soil bacteria and fungi before plants can use them, so they typically are more slowly released, especially during cold weather when soil microbes are not as active.Д«ut organic fertilizers have advantages. Organic fertilizers usually contain plant nutrients in low concentrations. If you need only a certain element such as nitrogen and want it to be quickly available to your plants, an inorganic fertilizer such as ammonium nitrate might be in order. Some nutrients, such as nitrate, are quickly available for uptake by plant roots, Penhallegon said.

However, since they are lost from the soil quickly, you may have to fertilize plants several times during the growing season unless you use a specially formulated, slow-release type. These nutrients are in a form readily available to plants. Inorganic fertilizers usually contain only a few nutrients вЂ“ generally nitrogen, phosphorus, potassium, sulfur and sometimes micronutrients, either singly or in combination. Inorganic fertilizers such as ammonium sulfate or ammonium phosphate are often called commercial or synthetic fertilizers because they go through a manufacturing process, although many of them come from naturally occurring mineral deposits. Organic fertilizers such as manures, compost or bone meal are derived directly from plant or animal sources, according to Ross Penhallegon, horticulturist with the Oregon State University Extension Service. вЂ“ Spring is the time for thinking about fertilizers. Local, regional and community food systemsД¬ORVALLIS, Ore.Commercial fishing, crabbing and clamming.

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