4.  Hydroponics is a subset of hydroculture (the growing of plants in a soilless medium, or an aquatic based environment) and is a method of growing plants using mineral nutrient solutions, in water, without soil.  Terrestrial plants may be grown with their roots in the mineral nutrient solution only or in an inert medium, such as gravel, mineral wool, expanded clay pebbles or coconut husk.

6.  The two main types of hydroponics are  Solution culture  Medium culture.

7.  Solution culture does not use a solid medium for the roots, just the nutrient solution. The three main types of solution cultures are static solution culture, continuous-flow solution culture and aeroponics.

8.  Aeroponics is a system whereby roots are continuously or discontinuously kept in an environment saturated with fine drops (a mist or aerosol) of nutrient solution. The method requires no substrate and entails growing plants with their roots suspended in a deep air or growth chamber with the roots periodically wetted with a fine mist of atomized nutrients. Aeroponics

9.  In Static solution culture, plants are grown in containers of nutrient solution, such as glass Mason jars, plastic buckets, tubs, or tanks. The solution is usually gently aerated but may be un-aerated. If un-aerated, the solution level is kept low enough that roots are above the solution so they get adequate oxygen.

10.  In Continuous-flow solution culture, the nutrient solution constantly flows past the roots. It is much easier to automate than the static solution culture because sampling and adjustments to the temperature and nutrient concentrations can be made in a large storage tank that has potential to serve thousands of plants.

11.  The medium culture method has a solid medium for the roots and is named for the type of medium, e.g., sand culture, gravel culture, or rockwool culture.  There are two main variations for each medium, Sub-irrigation and Top irrigation

12.  Passive sub-irrigation, is a method where by plants are grown in an inert porous medium that transports water and fertilizer to the roots by capillary action from a separate reservoir as necessary, reducing labour and providing a constant supply of water to the roots

13.  In its simplest form, there are trays above a reservoir of nutrient solution. Either the trays are filled with growing medium (clay granules being the most common) and planted directly or pots of medium stand in the tray.

14.  No soil is needed for hydroponics.  Pests and diseases are easier to get rid of than in soil because of the container's mobility  It is possible to control the nutrition levels in their entirety - thus, lower nutrition requirements

15.  Without soil as a buffer, any failure to the hydroponic system leads to rapid plant death.  Pathogen attacks such as damp-off due to Verticillium wilt caused by the high moisture levels associated with hydroponics and over watering of soil based plants.  Many hydroponic plants require different fertilizers and containment systems.

16. Positive  The water stays in the system and can be reused - thus, a lower water requirement  No nutrition pollution is released into the environment because of the controlled system  No pesticide damage

17.  What is Hydroponics?  There are two main types/techniques of Hydroponics name ONE and explain.  Give two advantages and two disadvantages of the hydroponic system.  Discuss one impact of this system on the environment.

18. Oh Percival you ‘re so smart n sexy