Both commercially produced compost and homemade compost benefit soil by including organic matter, providing food for beneficial microbial life, enhancing the soil’s water-holding capacity and gradually releasing plant nutrients. Composts made with high quantities of manure or biosolids (sewage sludge) may be high in salts and can burn plants, but composts made with primarily plant residues do not generally contain troublesome quantities of salt. A typical N-P-K ratio for compost is 2-1-1, though its exact nutritional content depends on many factors. Compost that smells like ammonia or is not yet fully decomposed should be allowed to finish breaking down to avoid damaging plants. Compost also contains many micronutrients needed for plant growth.
The nutrient content of manure relies upon many factors, including its age, source and the presence of bedding materials. Due to potential pathogen exposure, raw manure should be avoided. Manure should be a minimum of 180 days old or fully composted before it’s applied to growing areas. In addition to containing macronutrients, manure is also a great source of several trace nutrients essential for plant growth.
Most cattle and horse manures have an average N-P-K ratio of 1-0.5-0.5 while poultry manures are typically better high-nitrogen fertilizers (3-1-1 on average). The nutrients in manure are not immediately available to plants and can take up to several years to be released by soil microbes. In most cases, about 50 % of the total nitrogen is available the first year, with the remainder being released slowly over several subsequent seasons. Manure is also an excellent source of organic matter but can contain weed seeds.
(7) Cottonseed meal
Cottonseed meal is a high-nitrogen fertilizer with an average N-P-K ratio of 6-0.4-1.5. It takes many months to be processed by soil microbes and digested so that it can release the nutrients it contains. Organic farmers should seek out organic cottonseed meal because cotton is often a genetically modified crop and lots of pesticides are used during its growth.
(8) Blood meal
A byproduct of slaughtering facilities, blood meal is definitely a high-nitrogen fertilizer with an N-P-K ratio of 12-0-0. Simply because of its high ammonia content, inappropriate use or over-fertilizing might lead to burned foliage.
(9) Alfalfa meal
With an average N-P-K ratio of 2-1-2, alfalfa meal provides plants not just with these macronutrients but also many trace nutrients. It takes one to four months to be digested by the soil microbes and for the nutrients to become available.
(10) Feather meal
Whilst it takes 4 months or longer to break down and release its nutrients, feather meal is a superb high-nitrogen fertilizer with an N-P-K ratio between 7-0-0 and 12-0-0. It is just a byproduct of poultry processing.