...................................................................................................................................................................................... 1Using Organic Nutrient SourcesCollege of Agricultural SciencesAgricultural Research and Cooperative Extension2...................................................................................................................................................................................... ContentsIntroduction .................................... 2USDA National Organic Standards Summary on Soil Fertility Management .................................... 3National Organic Standards Summary for Fertilizers and Soil Amendments Use ............................ 3When Nutrient Levels Exceed Crop Needs ..................................... 3Balance and Imbalance of Nutrients in Organic Nutrient Sources ........... 4Nutrient Availability from Organic Nutrient Sources ............................. 4Increasing Soil pH, Calcium, Magnesium Levels ........................... 4Decreasing Soil pH ......................... 4Recommendations for Nitrogen, Phosphate, and Potash ................... 5Soil Organic Matter Content ........... 9Mineralization ................................. 9Using Compost ................................ 9Using Manure .................................14Additional Sources for Information ....................................14IntroductionWhen using organic nutrient sourc-es—for example, compost, manure, green manures, meals, and so forth—recommendations for crop nutrient needs will need to be trans-lated. Soil test reports do not give specific recommendations for using organic fertilizers/amendments. This is because the percentage and avail-ability of plant nutrients in such ma-terials is highly variable and usually depends on its source, method of storage, and the amount and type of materials used to make the nutrient source. Generally, the low nutrient content and often limited sources of many organic materials add to the difficulty in developing a specific recommendation. This guide is intended to help growers interpret soil test recom-mendations for using organic nutri-ent sources. Information presented applies to organic and conventional farms....................................................................................................................................................................................... 3USDA National Organic Standards Summary on Soil Fertility ManagementFor all growers, the goals of soil fertility management are to pro-vide sufficient nutrients to the crop grown, maintain or improve the soil condition, and minimize ero-sion. Organic growers are required to implement strategies to achieve these goals as indicated by USDA’s national organic standards. Practices include using sound crop rotations, green manures, and cover crops and applying plant and animal matter and allowable soil amendments according to the national list.National Organic Standards Summary for Fertilizers and Soil Amendments UseFertilizers and soil amendments that are in compliance with the national organic standards are available to complement other fertility practices. In addition, mined substances of low solubility can be used to sup-ply plant nutrients. Plant or animal ashes can also be used to improve soil fertility as long as they have not been combined or treated with a prohibited substance and are not themselves a prohibited substance.Soil Test ValuesSoil test values reported from the Agricultural Analytical Services Laboratory are interpreted as “defi-cient,” “optimum,” or “exceeds crop needs” (see Figure 1.). Crops nor-mally produce best when nutrients are present in balanced amounts at “optimum” levels. Application of a nutrient shown to be “deficient” should increase yield. When levels fall in the “exceeds crop needs” category, more than enough of a nutrient is present. When Nutrient Levels Exceed Crop NeedsSoil nutrient levels that exceed crop needs can be as bad as deficient lev-els. High soil nutrient levels might not only represent an economic loss but may also result in crop, animal, or environmental problems. To achieve maximum yield and qual-ity from each crop, a specific bal-ance among elements is necessary. Very high phosphorus levels (above about 310 pounds P2O5 per acre or 140 pounds of phosphorus per acre for vegetable crops) in the soil may lead to deficiencies of other nutri-ents, especially of iron and zinc. If potassium, magnesium, or calcium Soil TestingGood crop yields can be expected over a rather wide range of nutrient levels in most soils. The most desir-able level of each nutrient depends on such variables as the amount of rainfall, temperatures, amount of sunlight, soil texture, soil drainage, prevalence and severity of plant dis-eases, and the crop cultivar grown. The more intensive the type of production, the more important the information provided by a soil test. The Agricultural Analytical Services Laboratory at Penn State analyzes soil samples for pH, calcium, magne-sium, potassium, and phosphorous levels. If requested, the lab will also determine the organic matter con-tent and salt levels of soil samples for an extra fee. Soil samples must be submitted in standard sampling and mailing kits, which can be pur-chased from local Penn State Coop-erative Extension offices. Other laboratories also conduct soil analysis. Whatever soil testing system is used, it is important to stick with it and develop a feel for the relationship between test results and the response of the growing crops. Crop response with balanced fertility is what really counts.Figure 1. Example soil test report illustrating “deficient,” “optimum,” and “exceeds crop needs” categories for nutrient levels. Soil TeST reporT for: addiTional copy To: daTe lab # Serial # counTy acreS field id Soil 11/12/2004 S00-02986 0 2122 Soil nuTrienT leVelS deficient optimum exceeds crop needs Soil pH 6.5 phosphate (p205) 321.0 lb/a potash (K20) 336.0 lb/a Magnesium (Mg0) 1813.0 lb/a calcium (ca0) 6088.0 lb/a recommendations for: SWEET CORN (FRESH MARKET)4...................................................................................................................................................................................... is high, serious nutrient imbalances can occur. When potassium