Too much phosphorus can turn the partnership off

Phosphorus often sits in soil that roots cannot reach. Fine fungal threads help. When the soil solution is already rich in phosphorus, many plants simply do not bother to host the fungus.

Manure heaps and high-P blends can push a bed into that zone. Test before you add more. Where phosphorus is already adequate, protect the living network instead of forcing another bag.

This is not a rate calculator. Local rules, the label, and a soil test set the number. If colonisation stays poor after careful inoculation, ask whether phosphorus, waterlogging, or missing host roots are the real problem.

In this series

• Fungi need living roots, air, and moisture — a bag is not a soil
• Put inoculant next to the seed or the transplant root
• Too much phosphorus can turn the partnership off
• Host crops keep fungi; long brassica or fallow sequences starve them
• Tillage, compaction, and waterlogging break the network
• Match the fungus type to the plant — vegetables are not pines