DOI: 10.36347/sjavs.2019.v06i11.004

Pages: 285-292

Tropical lowland rice cropping is often facing with iron toxicity ([Fe2+] soil> 300ppm) constraint. This edaphic constraint is commonly observed in West African lowlands. It can cause yield reduction in a range of 10 to 100% depending on the concentration of iron in the soil solution and the cultivar used. Applying fertilizers and amendments have been recommended, including silica use. However, the high cost of the industrial silica limits its application. Hence the initiative to explore the potential of kaolin (54.7% SiO2) as a natural source of silica. Two pot experimentations were conducted during two successive rice cultivation cycles when applying 900 ppm of Fe2+. Five kaolin treatments were tested (T0 = 0 kg kaolin ha-1, T1 = 366 kg kaolin ha-1, T2 = 735 kg kaolin ha-1, T3 = 1097 kg kaolin ha-1and T4 = 1465 kg kaolin ha-1) in a randomized complete blocks with 5 repetitions for each experiment. Twenty one days old plants were transplanted into a pot (treatment). After transplanting, only plants from T1, T2, T3 and T4 survived until yielding. The dose of 366 kg ha-1 was sufficient to inhibit the toxic effect of iron on the development of the rice plant. The results show that kaolin input improved grain yield of rice (0 t ha-1- 1.08 t ha-1). The dose of 1465 kg kaolin ha-1 gave the higher grain yield (1.08 t ha-1). Response of rice to kaolin doses was more linear (RDG = 0.98 × Dose) than quadratic, indicating 1391.75 t ha-1 of kaolin as the optimal dose (1.054 ± 0.07 t ha-1) under iron toxicity condition of 900 ppm Fe2+.