What can I compost? Animal manures Straw, hay Vegetable matter Yard debris Wood shaving/chips Newspaper Fruit and vegetable wastes Fish processing wastes
Organic Production Manures 1.Raw manure OK if crop is not for human consumption 2.Incorporated >120 days before harvest if edible is in direct contact with soil or soil particles 3.Incorporated >90 days before harvest if edible is not direct contact with soil or soil particles
Organic Production Compost non animal materials Plant residues, etc No specific composting regulations
Organic Production Compost animal materials 1.Initial C:N 25:1 – 40:1 2.Meet PFRP 3.In vessel or covered 131-170 o F, 3 days, All portion of pile meets this temperature. 4.Turned windrow 131-170 o F, minimum 15 days with 5 turns.
Plant Nutrients Major Nutrients Nitrogen Phosphorus Potassium Calcium Magnesium Sulfur Micronutrients Boron Iron Manganese Zinc Copper Chloride Molybdenum
How nutrients become available Mineral Matter Organic Matter K Mg Ca N S P K + NH 4 + Ca ++ SO4 -- soluble, available Not available - - -- - - - - - -- Ca ++ K+K+ clay OM - - - - - - Mg ++ K+K+
Nutrient Anion Availability AnionBindingSolubility PO 4 -3 stronglow BO 3 -3 mediummedium SO 4 -2 v. weakhigh NO 3 - v. weakv. high
Organic N NH 4 + NO 3 - LeachingGases Plants, Microbes Plant residues, Manure Nitrogen Cycle
Organic Materials Little or no processing Low nutrient content Slow release of nutrients Plant, animal, or mineral sources
Processed Manures Heated >150 o F for 1 hour and less than 12% moisture
Organic Materials: Slow release nutrients Plants can only take up nutrients that are in available form (simple, soluble ions). Most nutrients in organic materials are in complex organic molecules or minerals, and are not immediately available to plants.
Slow release nutrients Biological processes slowly release the nutrients in organic amendment into available forms. Rate of nutrient release depends on the nature of the amendment and environmental conditions.
Nutrient uptake The forms of nutrients taken up by plants are the same for all types of fertilizer -- manufactured or organic.
Organic materials: Fertilizers vs. Soil amendments Fertilizer 1. High nutrient content and availability. 2. Main benefit is nutrients. 3. Relatively small amounts applied. Soil amendment 1. Low nutrient content and availability. 2. Main benefit is organic matter. 3. Large amounts applied.
Carbon:Nitrogen ratio Low C:N supplies N to plants High C:N ties up N by biological immobilization
C:N ratio and N availability C:N <10:1 10:1 to 20:1 20:1 to 30:1 >30:1 N availability High Med - Low Very Low Negative
High N Content C:N < 10:1 Rapid N availability Use as a fertilizer Over application leads to excess nutrient levels in soil -- potentially harming crop and water quality.
High N Content Examples Poultry manure Packaged organic fertilizers Fresh dairy or goat manure
Moderate N Content C:N 12:1 to 25:1 Slow N availability Can add large amounts without risk of over-fertilization Use as a soil amendment Expect some N immobilization (tie-up) shortly after application.
Clopyralid in Compost What’s the story? N Cl COOH
Clopyralid What is it? A herbicide that kills many broad-leaved weeds. It is used on lawns, hay crops, wheat, and some other crops Legumes, nightshades, and composites are the most susceptible families.
Clopyralid How does it get into compost? Applied to lawns by lawn care companies Clippings recycled as yard debris become feedstock for compost. Breakdown of clopyralid in compost is slow.
Clopyralid Other sources of contamination Manure from horses fed grass hay treated with clopyralid Straw from grain crops treated with clopyralid
Clopyralid Will contaminated compost kill my plants? No. But, there may be symptoms of damage on some susceptible garden plants, such as peas, beans, potatoes, and tomatoes. Most plants are unaffected by clopyralid.
Peas, beans and marigolds grown in 3:1 v/v compost:perlite mix Peas and beans show symptoms, marigolds show no symptoms.
Leaf from tomato plant grown in unamended soil. Leaf from tomato plant grown in soil amended with 50% compost.