Manure is the by-product of livestock and poultry production. It includes the urine, feces, bedding materials, wasted feed, and sometimes wash water from livestock operations. The value of manure in crop production is often underestimated. In Ontario livestock generate over 25 million tonnes of manure annually.
Manure contains all the nutrients needed by crops, but not necessarily in the proportions needed for specific soil and crop conditions. Manure and other organic amendments are nutrient-rich and contain nitrogen, phosphorus, and potassium as well as secondary nutrients such as calcium and sulphur and micronutrients that include magnesium, zinc, manganese, and boron. Manure is considered an organic fertilizer and is a source of carbon and organic matter that is beneficial for maintaining or improving soil health.
Organic amendment is a term that includes manure but may also include other materials derived from living organisms, including cover crops (green manures), composted materials, anaerobic digestate and other non-agriculture sourced materials (NASM) including products such as food processing waste and sewage biosolids. Organic amendments can also include registered fertilizer products that are derived from organic sources (e.g., biosolids pellets)
Manure and organic amendments can be managed in liquid or solid form. Nutrient composition varies significantly between materials. Management will differ depending on nutrient and moisture content. Liquid manure (less than 18% dry matter) has a higher proportion of nutrients – especially nitrogen – that is available quickly to crops, while solid manure (greater than 18% dry matter) has more nutrients in organic form – and requires microbial decomposition resulting in a slower release of nutrients and carbon.
Nutrient Management Planning
Nutrient management planning helps to optimize beneficial use of nutrients for economic crop production. Nutrient management planning matches farm-generated and purchased nutrients to crop needs and soil fertility requirements. It considers nutrient inventories from the farm, including background soil fertility, nutrient credits from legume crops or previous manure applications, and available nutrients from applied organic amendments.
Nutrient management planning focuses on minimizing environmental impacts of nutrients by using a 4R approach – right product, right rate, right time, and right place. 4R nutrient stewardship balances manure nutrient efficiency with commercial fertilizer nutrients supplemented where needed and considers potential environmental risk.
Right Product considers:
- available nutrients from applied or planned organic amendments, including nutrient credits from previous applications.
- commercial fertilizer additions to balance crop needs or align soil fertility levels.
- potential for nutrient (environmental) losses based on timing or placement.
Right Rate considers:
- matching the organic amendment application rate with crop needs, usually phosphorus, or nitrogen and supplements additional needs with commercial fertilizer.
- regular manure/organic amendment analysis to help determine estimate available nutrients and help set application rate.
- calibration of application equipment to match intended rate.
- uniform application/distribution of organic amendments
Right Time considers:
- applying manure as close to crop needs considering composition and available nutrients
- solid manure applied in late summer/early fall will have highest N availability for spring-planted corn.
- liquid manure applied in spring or into standing crop will have highest nutrient availability.
- never applying organic amendments to frozen or snow-covered soils, unless immediately incorporated.
Right Place considers:
- selecting the field(s) that need the nutrients most.
- injecting or quickly incorporating manure to minimize nitrogen volatilization and reduce risk phosphorus runoff.
- minimizing the potential for nutrient movement via leaching, runoff or preferential flow to tile drains.