Week 1 Aquaponics

Q: What must hydroponic culture provide for plants

A: Mechanical support, essential mineral nutrients, water, oxygen for roots, and a way to remove CO2 and leachates.

Q: How can CO2 and leachates be removed from hydroponics systems

A: Recirculation with filters, drainage, or degassing.

Q: What is an advantage of hydroponics over soil in terms of plant nutrition

A: Mineral nutrients are maximally available; concentration can be reduced compared to soil.

Q: Why is hydroponics considered “clean agriculture”

A: Growth medium can be sanitized, reducing disease and pests.

Q: What are the advantages of hydroponics for plant spacing

A: Closer spacing and higher cropping density are possible, limited only by light.

Q: What are two major pest and weed advantages of hydroponics

A: No weeds and reduced disease/pest risk due to sanitization.

Q: How does hydroponics affect water availability for plants

A: No wet/dry cycles; water status is stable when aeration and nutrients are maintained.

Q: How do maturity and yield compare between soil and hydroponics

A: Hydroponic plants mature faster and yield more, especially in controlled environments.

Q: What are the disadvantages of hydroponics

A: High startup cost, rapid disease spread, nutrient accumulation, failures from neglect/pH issues, transplant shock, and difficulty getting organic certification.

Q: What are the five cardinal factors of plant growth

A: Light, temperature, water, nutrients, atmosphere (CO2, O2).

Q: What is the key difference between open-field agriculture (OFA) and controlled-environment agriculture (CEA)

A: CEA avoids limiting factors, allows faster cropping, and is 10x more productive (up to 100x in vertical farming).

Q: What is deep water culture (DWC) hydroponics

A: A system where roots grow in nutrient solution, often in opaque containers with strong support and aeration.

Q: Why must hydroponic systems be strong and corrosion-resistant

A: Water is heavy (8.34 lbs/gal), and nutrient solutions can corrode materials, releasing toxins.

Q: What is the maximum oxygen concentration in water for roots

A: About 8 ppm; continuous supply is needed for respiration.

Q: What nutrients are included in a “complete” hydroponic solution

A: 13 of 16 essential elements: C, H, O, P, K, N, S, Ca, Fe, Mg, B, Mn, Cu, Zn, Mo, Cl.

Q: What is the difference between Hoagland’s solution #1 and #2

A: #1 has N as nitrate (NO3-); #2 has N as ammonium + nitrate.

Q: How are stock solutions typically stored

A: Refrigerated concentrates; macros separated (Ca & phosphate), micros together, Fe as chelate in brown bottle.

Q: What is the typical pH range for hydroponic nutrient solutions

A: Between 5.5 and 6.5.

Q: What happens to pH when nitrate (NO3-) is the main N source

A: Solution pH rises.

Q: What happens to pH when ammonium (NH4+) is the main N source

A: Solution pH falls.

Q: Why is pH management critical in hydroponics

A: High pH causes chlorosis and stunted growth; low pH damages roots.

Q: What is the biggest reason hydroponics systems fail

A: Poor pH control.

Q: Why is NH4+ alone toxic to many plants

A: High concentrations cause toxicity; some nitrate is needed to reduce NH4+ effects.

Q: What is a common issue with matrix-based hydroponics and pH

A: No buffer capacity → pH extremes; leaching required, which wastes water and nutrients.

Q: Why is hydroponics important to aquaponics

A: Because aqueous solutions flow between aquatic and plant compartments; continuous flow is required when hydroponics is liquid, and periodic flow when hydroponics has a solid matrix. Root zone is critical for nutrient cycling.

Q: What does "hydroponics" mean

A: From Greek "hydros" (water) and "ponos" (labor/cultivation).

Q: How many essential mineral elements are soluble in water

A: 15 of the 16 essential mineral elements.

Q: What are the two main types of hydroponics

A: Matrix/solid substrate culture and solution culture.

Q: What are examples of solution culture hydroponics

A: Deep water culture (DWC), nutrient film technique (NFT), and aeroponics (fine mist).

Q: Who first mentioned water culture of plants in 1627

A: Francis Bacon, in “A Natural History.”

Q: Who did early water culture experiments with spearmint in 1699

A: John Woodward — plants in “dirty water” grew better than in clean water.

Q: Who developed soilless cultivation techniques between 1859–1875

A: Julius von Sachs & Wilhelm Knop.

Q: Who introduced the term “hydroponics” in 1929

A: William F. Gericke (UC Berkeley).

Q: Who created the classical hydroponic nutrient solution in 1938

A: Dennis R. Hoagland and Daniel Arnon.