Maximum Yield Australia/New Zealand July/August 2020 | Page 34

WHAT SYSTEM
IS BEST FOR YOU?
by Dr. Lynette Morgan
Open and closed hydroponic systems both have their own
pros and cons and suitability for different growing situations
and inputs. Understanding how each system influences the
composition of the nutrient solution is essential in optimising
plant nutrition from whichever system is being used.
Management of the nutrient solution applied to hydroponic
plants falls into two basic categories: those that are closed
and recirculate the solution, either continually or intermittently,
and those that don’t recirculate the solution, termed open
systems. Closed systems are more widely used amongst
indoor growers, while in the past, drip-irrigated open systems
were commonly seen in commercial greenhouse production
of a wide range of hydroponic crops. A degree of solution
management skill, monitoring, and regular adjustment are
the basis of both open and closed systems, however, each has
different advantages when it comes to plant production.
System Differences
Closed systems that recirculate the nutrient solution are
often based around solution culture and include NFT,
DFT, float/raft/pond systems, aeroponics, aquaponics,
and ebb and flow. In these systems the nutrient solution
is made up to working strength, EC and pH are adjusted,
and the same solution is applied to the plants either
continually or intermittently. Recirculating systems are
regularly topped up with water, the solution is managed
on a regular basis and is only partially or fully replaced
when required.
34
Maximum Yield