CHARACTERIZATION OF SOME BENCHMARK WETLAND PEDONS IN NIGERIA FOR RICE CULTIVATION

Abstract

Five potentially iron (Fe²⁺) toxic wetland pedons on inland valley bottom and flood plains located in two agro-ecological zones were characterized and classified to identify major soil constraints and then evaluated for their potential for rice cultivation. The pedons exhibited highly variable chemical properties: acidic pH reaction, low organic carbon contents, available P, and ECEC and high extractable-Fe (amorphous, total, and organic). Field experiments were conducted (1994 and 1995 wet seasons) to evaluate the performance of two lowland rice (cv ITA 212 and Suakoko 8) on these soils. In the first year, the grain yield valley bottom soils ranged between 3.47–5.69 t ha⁻¹ (ITA 212) and 4.06–4.69 t ha⁻¹ (Suakoko 8). However, in the second year, grain yields were much lower ranging between 1.71–2.23 t ha⁻¹ (ITA 212) and 2.61–2.69 t ha⁻¹ (Suakoko 8). In both seasons on flood plain soils, the grain yield ranged between 1.22–2.94 t ha⁻¹ (ITA 212) and between 1.02–2.80 t ha⁻¹ (Suakoko 8). Factors, which relate significantly to grain yields, were extractable-Fe, pH, Mg and available P while those that relate significantly to the straw yields were base saturation, extractable Fe (0.1 N HCl), available P and exchangeable Mg.

ACKNOWLEDGMENTS

The grant for this project was from African Development Bank (AfDB) and West Africa Rice Development Association (WARDA). The assistance of Dr. J.L. Pleysier and Mr. J. Uponi of the Analytical Service Laboratory, IITA, Ibadan is also duly acknowledged.