Hydroponics

 

Hydroponics is a sub category of hydroculture. It 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 perlite or gravel. The type of system used at South Andros High School is an NFT (nutrient film technique). 

Nutrient Film Technique

 

The nutrient film technique used in South Andros High School incorporates 3 inch diameter plastic net pots for the plants, roots soaked in nutrient enriched water, and perlite for growing material. The system uses two shade houses. One is used to grow celery and romaine lettuce, and the other is used to grow tomatoes.

 

The water levels are at a pH between 5.5 and 6.5. The students use baking soda to increase the pH making the water more alkaline and vinegar to decrease the pH and make the water more acidic. the TDS (total dissolved solid) is 220ppm. 

Growing Medium

 

Growing medium is the material that supports the root system of the plants. It can consist of a variety of substances such as perlite, vermiculite, gravel, moss, sand, or clay pellet. The hydroponics system at South Andros High School uses perlite, which is a mined material made of volcanic glass when heated at more than 1600 degrees. Perlite is porous, which enables it to hold large amounts of water and makes it light to handle.

Micronutrients 

 

Trace elements are required for healthy plant growth to prevent stress, disease, pests, fungus, and bacteria. Some of these elements include calcium, magnesium, sulfur, boron, cobalt, copper, iron, manganese, molybdenum, and zinc. All of these elements contribute to increased growth, yield, and nutrient content. The system gains these micronutrients through fertilizer called HydroGro. 3/4 of a teaspoon of fertilizer for each gallon of water is added to the system. It costs the school $100 per bucket of fertilizer, which sustains the South Andros hydroponics system for 1 year.