Substrates
Substrate Selection and Management
Select
container substrates that are best adapted to the plants species and management
(see section on Container Substrates).
Avoid substrates that are too porous and require frequent watering (see section on Container Substrate Physical
Properties). Methodology for determining substrate physical properties is
given in Appendix B.
Plant Nutrient
Requirements
Fertilizer Type and Rate
The general
principle is to apply the least amount of fertilizer to maximize plant growth,
but in a way that minimizes nutrient leaching. This can be accomplished with
different management strategies using dry granular fertilizer or solution
fertilizer applied at various rates, depending on the intensity of management (see sections on Pre- and Post Plant
Fertilizer Applications and Controlled-Release Fertilizer).
Plant Nutrient Requirements and Application
Fertilizer
applications should be made at recommended rates based upon plant requirement
(species), container size, plant age, growth rate, and the time of year (see sections on Pre- and Post Plant
Fertilizer Applications and Controlled-Release Fertilizer).
Fertilizer
applied through the overhead irrigation system should be properly managed, so
it does not greatly increase the chance of significant nutrient runoff from the
nursery (see section on Fertilizer in
Irrigation Water).
Monitoring Substrate Nutrients
Nutrient
levels in container substrates should be monitored to assure levels are
appropriate for desired growth. This should be performed on representative
plants of similar size and with similar fertilizer and irrigation programs (see section on Monitoring Container
Substrate Nutrient Status).
Fertigation
application rates and reapplication of granular fertilizer should be based on
monitoring the electrical conductivity (EC) of substrate solution. EC should be
checked at least monthly during plant production (see section on Monitoring Container Substrate Nutrient Status).
Record of Fertilizer Application
An accurate
record should be made of fertilizers applied for each plant type (high, medium
or low nutrient requirement) and container size. This data should be recorded
in such a way that total nitrogen and phosphorus applied for the nursery could
be calculated on an area basis or on a crop basis (see section on Record of Fertilizer Application). Another approach
would be to keep fertilizer receipts to calculate per acre application amounts
of N and P for the nursery. See Appendix
C for examples. Fertilizers can be applied through the irrigation system or
directly on the substrate surface (granular or controlled-release. Fertilizer
type, plant species, container size, and time of year are factors affecting
fertilizer application amount.