Potentials of soilless substrates from biochar and rice husk as a replacement for cocopeat in Nigeria on tomato (Solanum lycopersicum)

Increase in the number of screen house cultivation practices has a fear for escalation in the cost of cocopeat coupled with lower return rate or benefit/cost ratio. Therefore, a study was conducted during 2019 at the Landmark University, Kwara State, Nigeria to evaluate the potentials of biochar and rice husk combinations to replace cocopeat as a soilless substrate on tomato. The treatment consisted of (1) Rice husk (RH) 100%, (2) Cocopeat (CP) 100%, (3) Biochar (B) 100%, (4) RH + CP 70/30%, (5) RH + B 70/30%, (6) RH + CP 50/50%, (7) RH + B 50/50%, (8) CP + B 50/50%, (9) CP + B 70/30% and (10) soil 100%. The treatments (substrates) were arranged in a Completely Randomized Design replicated four times under screen house conditions. The results of this study revealed that soilless media (CP, RH and B alone and combinations) reduced bulk density and increased water holding capacity (WHC), pH, CEC, plant height, number of leaves, leaf area, root weight, and fruit weight of tomato relative to the soil. CP has higher WHC, plant growth and yield parameters, mineral, TS, and TSS values and lower bulk density relative to other substrates/combinations and soil but similar to RH + CP 50/50. The yield differences between CP alone and RH + CP50/50, RH + B50/50, B alone, CP + B 70/30, RH + B 70/30, CP + B50/50, RH + CP70/30, RH alone and soil were 4.5, 10.8, 47.3, 58.1, 72.3, 109.7, 110.9, 143.6 and 484.3%, respectively. The soil has higher mineral contents relative to other substrates combinations except for CP. Therefore, RH + CP 50/50 is recommended, but based on the economic analysis, RH + B 50/50 has the highest benefit/cost ratio and therefore recommended as a good substitute for expensive cocopeat.