There is a paradigm shift today in turf fertility. Organic fertilizers are here to stay and rightfully so. Superintendents that have implemented organics into their programs are having great results. The secret is out that organics work and can help alleviate a multitude of problems for today’s turf manager. The question has shifted from Why organic fertilizers? to Which organic fertilizer do I use? To help answer that question, we need to look at the main component in each of the four types of organic fertilizers: sewage sludge, manure, composts and animal/plant proteins.
Sewage sludge is a dry product created during the biological and physical treatment of wastewater from homes and industry. This product has been around for years and increasing each year. Disposal of this product has been through landfills, incinerators and ocean dumping. Environmental factors have made many of these options impossible. Several major metropolitan areas across the U.S. have constructed facilities to process sludge into fertilizer with probably many more to follow.
To process, the water is removed and the remaining sludge is sterilized at 800-900ÁF killing any harmful bacteria and minimizing offensive odors. Although sludge may contain nitrogen (5 to 7%) and phosphorus (1 to 3%), it does have a number of drawbacks. The excess heat used in drying and sterilizing often bind the proteins so tight that the nitrogen is not readily available to the plant. Sludge can also contain alarming amounts of undesirable elements such as arsenic, mercury, cadmium, chromium, lead and nickel. Sewage treatment plants are routinely monitored for heavy metal content by state and federal environmental protection agencies. These elements can contaminate soil and water.
Manures increased interest in the environmental management of poultry and other livestock manure has emphasized the need for alternative disposal systems. Golf course acreage is viewed as an excellent opportunity to dispose of animal manure and still make money. To understand how manure may work on your turf, it is important to understand how it is collected. Manure can be collected from either broilers (eating chickens) or layers (chicken used for egg production). The diets of each vary greatly. Cultural practices also influence the quality of manure. Farmers can use wood shavings, straw or other fibrous materials as bedding. They clean the bedding every 8-16 weeks. The bottom line is there is a large amount of variance in the nutrition content of the manure. Nitrogen (2 to 5%) and phosphate is (1 to 5%) are both derived from manures.
Composting manures is the process of using the natural aerobic and anaerobic microbes along with the free ammonia found in the waste to breakdown complex cellulose fiber into more available nutrients. The used bedding and manure are allowed to compost for a certain period of time, with the material being turned periodically to allow the process to continue throughout all the material. If the composting manure is not turned and worked properly, problems can occur. If the middle of a compost pile has not been worked through, composting may not occur in that section. This will leave soluble nitrogen, that, when used in a fertilizer, will burn turfgrass. If the pile as a whole is not composted long enough, the carbon to nitrogen ratio (C: N ratio) will not be in balance resulting in a temporary loss of nitrogen turning your turf yellow. Manures are generally low in nitrogen (3 to 4%) and are variable in their release characteristics.
Composts are not fertilizer, but are often classified as such. Compost can be derived from any organic matter and its nutrient content will depend upon its original raw material. These include grass clippings, leaves, other plant materials and garbage. Properly composted organic matter is an excellent soil amendment loaded with beneficial microbes. If compost is properly made, its food energy has already been used. This results in a low nutrient analysis with nitrogen usually less than 1%. Compost can be used as a topdressing to add organic matter or as a construction mix to aid in soil tilth. Caution should be used when applying compost as a topdressing due to particle size and uncomposted pieces of organic matter. If composting is not complete, an imbalance in the C:N ratio can result in a sudden decrease in nitrogen from your soil.
Animal and plant proteins are the most expensive and concentrated source of nutrients among organic fertilizers. Nature Safe is a type of this organic fertilizer. Ingredients such as meat meal, feather meal, bone meal, poultry meal, blood meal and fish meal all fall into this category. Nitrogen levels (5 to 14%) and phosphorus levels (5 to 14%) vary depending on the source of the ingredient. The high nitrogen levels often cause prospective buyers to question whether the fertilizer has been spiked with a synthetic nitrogen source. Higher nitrogen formulations can mean less volume of product to be worked into the turf. These proteins are derived from the feed or food industries rather than waste by-products. Therefore, they have been more carefully processed to insure quality and availability of nutrients. Protein sources derive their nitrogen from amino acids, which will be digested by the soil microbes and released over time. As the nitrogen is released, it is bonded by the soil in an ammonia form that prevents leaching. Protein based fertilizer also contain abundant levels of minerals and vitamins. These minerals and vitamins will chelate meaning they bind to the amino acids or other organic molecules. These minerals then become more available for plant absorption. Protein based fertilizers are an excellent food source and stimulant for beneficial soil microbes. Because protein based ingredients are treated more carefully than waste by-products, their release characteristics are more predictable. This results in a higher quality product that provides fertilizer efficiency and value, meaning more bang for your buck!