2.Growing Media and Water Culture

Question 1

Advantages and disadvantages of hydroponics?

Answer 1

Advantages:

• No growing media needed so reduced risk of plant disease/pest
• Better growth and yield due to precise control of the nutrition requirements and root temperature
• Evaporation is reduced and loss of water and nutrients through drainage is minimal.
• There can be a reduction in labour costs
• Quicker turnaround between crops in protected environments
• Can free up land for other uses and uses less land (especially if grown vertically)

Disadvantages:

• High initial costs to install and the controls of more sophisticated systems
• Environmental concerns as some materials used (rock wool) does not break down at all easily
• Nutrient and pH levels need to be closely monitored

Question 2

Name 2 types of hydroponic systems?

Answer 2

• NFT (nutrient film technique)
• Substrate culture (rockwool)

Question 3

How does NFT work?

Answer 3

• Method of growing in a shallow film of flowing water where the nutrient solution is constantly recirculated along plastic troughs (lined with capillary matting)
• The troughs must be on a slope to prevent stagnation of water
• NFT provides a constant flowing supply of nutrient solution past the plant roots
• The plants can be sat in troughs with holes or placed in blocks of rockwool, or something similar

Question 4

What is substrate culture?

Answer 4

• Plants are propagated in Rockwool blocks
• Larger pores in Rockwool hold air; and smaller pores hold water
• Nutrient solution is provided via drippers to each block with a constant flow
• Excess solution leaves via drainage holes and is run to a recovery channel
• The water may be recirculated after appropriate treatment (sterilization) and adjustment
• pH and nutrients are adjusted as for NFT

Question 5

Where can water culture be used?

Answer 5

• Green walls
• Vegetable production (crops of high economic value such as tomatoes, cucumbers, peppers, melons, lettuce, carnations, roses and strawberries)
• Interior landscaping – some houseplants can be successfully grown hydroponically (including those suitable for interior green walls). Usually, these use expanded clay aggregates.

Question 6

What are the considerations for using water culture?

Answer 6

• Aeration
• Nutrients, pH control, water supply & quality
• Pest & disease control
• Automation

Question 7

List the advantages of green walls

Answer 7

• Green walls can be used internally or externally
• When used internally they help improve the air quality, take in Co2 and giving off o2
• Increase humidity
• Offices raise employee job satisfaction
• Hospital speed patient recovery
• Absorb noise
• Can be used to grow salad crops, herbs and strawberry (must be appropriate for situation )