SOIL CHARACTERISTICS OF THREE IRON TOXIC SITES IN NIGERIA
1J. Abah, 2K. N. Drame, 2M. Sie, 2B. Manneh, 3M. E. Abo, 3A. Umar, and 3M. Bashir
1Department of Chemistry, Benue State University, Makurdi, Nigeria
2Rice Research Division, National Cereals Research Institute, Badeggi, Niger State, Nigeria
3Africa Rice Center, Cotonou Benin.
E-mail: abahjim@yahoo.com
ABSTRACT
Irrigated and rain-fed land often showed some sort of nutritional constraints to rice growth caused by either nutrient deficiencies or toxicities. However, comprehensive data on soil physicochemical characteristics of most lowland ecosystems used for rice cultivation in Nigeria are scanty, making it a complex problem to identify specific yield constraint. This study determined the soil characteristics of rain-fed experimental sites for the Stress Tolerant Rice for Africa and South Asia (STRASA) at Adike (Benue State), Edozighi (Niger State) and Ndubia (Ebonyi State), Nigeria using standard laboratory methods. The mean concentrations of ferrous iron (Fe2+) within 0-20cm and 20-40cm of the soil layers ranged from 800-1230ppm and 1010-1780ppm respectively. The mean iron toxicity score of the 80 lines of rice tried in the experimental sites varied between 1.75-3.65%. Zinc contents of the soil layers ranged from 1.09-2.29ppm and 3.43-4.44ppm. The Physicochemical analysis of the farm soils revealed low levels of nitrogen, potassium, organic matter, cation exchange capacity and acidic ecology with pH range of 4.15-5.22. However, available phosphorus was quite high in all the project sites. The experimental sites recorded zinc deficiencies while the high soil levels of ferrous iron in all the project sites is indicative of iron toxicity hot spot. The low cation exchange capacity of the soils has implication on the vulnerability of the sites to leaching of nutrient elements. Therefore, proper agronomic management is required to enhance rice productivity in the experimental sites.
Key words: Ferrous Iron, Toxicity, Physicochemical Parameters, STRASA