Ither locked up due to inadequate negative ionic exchange surface area or actually lacking food.
Is your biochar up to 10% for overall soil volume?
..using basalt rock dust?..worm castings?
..a pot dump and re-amend may be in order.
1 cup per cubic ft of fish meal,comfrey,or other organic high quality food source.
1 cup per cubic ft Acadian or cold processed Atlantic kelp meal
1 cup per cubic foot Pacific Pearl oyster shell powder
We offer a seasonal biodynamic accumulator food pack in my LOS store...as well as plug and play soil kits.
The seasonal BDA mix contains comfrey,mullen,plantain,sorrel, and catnip. All biodynamic nutrient dense food sources fungal and bacterial colonies can breakdown...thus made ionically available to the plant.