A detailed look at soil organic matter services

INFORMATION ON THE BENEFITS AND CHALLENGES OF COMMONLY USED SOIL ORGANIC MATTER ADDITIVES

Product Benefits Challenges
Livestock manure
  • Available on-farm, manure provides many of the required macro and micro nutrients for year of application and beyond. 
  • Manure supplies organic matter which will help improve soil health
  • relatively consistent over time
  • Manure contains odours and pathogens which, if not managed properly, can lead to water contamination. 
  • Application to wet soils can cause soil compaction. 
  • Manure nutrient content can be variable and usually not in the proportions needed by crops
  • Application to crops further from the manure storage takes time and planning.
NASM – Sewage Biosolids
  • Benefits are similar to manure from nutrient and organic matter perspective
  • Biosolids are usually custom applied and applied at no cost for the farm
  • Regulatory changes have resulted in biosolids application rates set to meet crop needs
  • There is little or no potash contained in sewage biosolids
  • Biosolids contain trace elements (ie lead) 
  • Wider setbacks are required from residences and sensitive features.
  • Setback areas require additional trip with other nutrient source (commercial fertilizer) 
  • Regulatory requirements must be met with the application of sewage biosolids  
N-Viro
  • Biosolids processed with kiln dust provide an organic matter and liming benefit with high calcium and potassium ideal for low pH sandy soils. 
  • Since this material is regulated through CIFA, it does not require additional approvals before use. 
  • N-Viro is applied at about 2–3 T/ha
  • The material is dusty and has a relatively high salt content. 
  • Planting immediately following application should be avoided – to prevent seed burn – where material has been applied at a high rate (or banded) to dry, sandy soils.
Biosolids Pellets
  • Process takes digested sewage to biosolids cake (dewatered, thickening agents added) then pelletization (heating and drying) process occurs
  • Source of organic matter, nitrogen and phosphorus and micro nutrients
  • Regulated through CFIA
  • Processes from various treatment plants are similar in macro nutrient composition, but micro nutrients (aluminum calcium or iron) can vary depending upon process used and could affect phosphous availability in low pH soils
  • Low potash content
  • Application limits ) may exist due to trace element content (ie Toronto pellets limited to 1 T/ha due to copper levels)
Municiple Green Bin Compost
  • Relatively good balance of available macro and micro nutrients and organic matter
  • Properly cured compost has low environmental risk for nitrogen losses, therefore can be a good fit for late summer /early fall applications.
  • Fits will in programs where application occurs once per rotation at higher application rates (nutrients and economics)
  • Contaminants (ie plastics) are removed but very low levels can often still be found in the material
  • Product availability (transport, application and cost logistics) from production site to farms
  • Temporary field storage can cause some compaction damage from truck traffic and loading equipment.
  • Several municipalities have green-bin compost programs. Consistency of product composition varies between municipalities, therefore testing and product analysis is important for determining rate and additional nutrient needs.
Anaerobic Digestate
  • A by-product of anaerobic digesters
  • Good balance of macro and micro nutrients and still significant organic matter – carbon contribution
  • Digestate composition will vary with inputs, therefore analysis is important in determining application rates and additional nutrient needs.
  • Low odour and pathogens (in a closed system) compared to raw manure.
  •  Limited number of anaerobic digesters (so far) therefore limited availability of digestate (so far).
  • Higher NH4-N levels and lower C:N ratio compared to pre AD inputs
  • Risk of environmental losses are higher with digestate – Liquid application can be difficult (to get low enough rate) if N content is high.
  •  Liquid digestate (especially product with high available N) should be applied to a growing crop. Spring application would be most economical; Environmental risk increases with late summer and fall application to bare soil.
  • Salt content (EC) in liquids can be high. Injection into narrow bands immediately followed by planting could lead to salt injury
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