Development of a low cost hydroponics system and a formulation for the tropics

Abstract

Simplifi ed hydroponics is a low cost aggregate hydroponics system which is practiced under natural climatic conditions with hand watering. Rice hull is a waste material which is not properly utilized and a mixture of rice hull and sand (3:2) was used in this system. A new nutrient formulation (NF) was developed using locally available commercial grade chemicals. A buffer system was incorporated to the nutrient formulation, ensuring that the pH was maintained in the optimum range. NF was composed of (in ppm), N = 167, P = 80, K = 281, Ca = 234, Mg = 57, S = 251, Cu = 0.01, Fe = 3.9, Zn = 0.13, Mn = 1.2 and Mo = 0.13. A fi eld trial was carried out for NF in the wet zone in Sri Lanka for tomato plants in simplifi ed hydroponic system. The nutrient uptake was monitored by measuring the change in weekly average electrical conductivity (EC) of the root solution (compared to the EC of the applied nutrient) of tomato plant beds. The pH of the root solution was in the suitable range and no adjustment was required indicating successfulness of the buffer in the formulation. The nutrient cost involved to produce 1 kg of tomato was about 70% less than other commercially available nutrients.