Blood meal

Blood meal is dried animal blood, composed largely of protein. Its high protein content is the source of its nitrogen, typically around 12%, with little phosphorus or potassium, so it functions essentially as a straight organic nitrogen source.

Source

Dried, ground animal blood from meat processing

Nitrogen content

About 12% total nitrogen, held in protein

Other nutrients

Little phosphorus or potassium

Release pattern

Faster than most organic nitrogen sources as protein mineralises

Blood meal supplies nitrogen, released as soil microbes break down its proteins to ammonium and then nitrate. Because a large fraction is easily mineralised, availability is comparatively rapid for an organic material, and the released nitrate is subject to the same leaching risk as mineral nitrogen.

• Protein nitrogen is mineralised to ammonium and nitrate by soil microbes
• Availability is relatively quick compared with slower organic sources
• Supplies essentially no phosphorus or potassium

Blood meal is used in organic systems to boost nitrogen for leafy and heavy-feeding crops or to correct visible nitrogen deficiency. Some growers also value its reputation for deterring certain herbivores, though it can conversely attract others, so this effect is inconsistent.

• Accepted as an input in many organic farming standards
• Suited to nitrogen-hungry, leafy crops and quick corrective feeding
• Should be worked into soil and not concentrated against roots or seed

Because it is concentrated and fast-releasing, over-application can burn roots and seedlings and can drive excessive vegetative growth. Sourcing of animal by-products is subject to biosecurity rules that vary by country, and the powder can attract scavenging animals to treated ground.