Root damage from contact with drilled fertiliser can delay or reduce germination and reduce plant growth.
What to look for
Paddock
Bare areas or poorer plant growth that is more common in sandy soils or specific drill rows.
Plant
Plants fail to emerge, have delayed emergence, and early growth stunting.
Cereals may have older leaf death but recover completely.
Canola and legume tap roots growth can be stunted reducing their capacity to use deep subsoil water.
Management strategies
Toxic effects of fertilser on crop germination can be avoided by banding fertilisers away from the seed or by top-dressing.
Banding about 5 centimetres below or to the side of the seed rows is usually sufficient to avoid germination problems.
Because nitrogen fertilisers can leach, banding nitrogen fertiliser above the seed rows was tested in trials, but reduced establishment and early vigour.
A 'safe level' cannot be stated because many contributing factors influence fertiliser toxicity on germinating seed.
Fertiliser may greatly reduce germination, but the remaining plants may grow luxuriantly in a high-fertiliser-responsive soil and produce a higher yield than would have occurred had a lower, non-toxic fertiliser rate been used.
