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

Abstract: Simplified hydroponics is a low cost aggregate hydroponics system which is practiced under natural climatic conditions with hand watering. Rice hull, a waste material, which is mostly under 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 field trial was carried out for NF in the wet zone in Sri Lanka for tomato plants in simplified hydroponics system. The nutrient uptake was monitored by measuring the changes 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 sufficient buffering in the formulation. The nutrient cost involved to produce 1 kg of tomato was about 70% less than other commercially available nutrients formulation.