Effects of Organic Materials on Phosphorus Forms under Submerged Condition in the Soils of Lake Geriyo Irrigation Project, Adamawa State, Nigeria

Abstract

Experiment was conducted at the landscape unit of Modibbo Adama University of Technology, Yola, to study the effects of organic materials on phosphorus forms under submerged condition in the soils of Geriyo Irrigation project. Soils were incubated with cowdung and poultry droppings at 5, 10 and 15 tons/ha for a period of 90 days. Soil samples were collected at 30, 60 and 90 after submergence and processed for analyses. Results showed that the soils were slightly acidic, low in total nitrogen, available phosphorus, effective cation exchange capacity (ECEC), and percent base saturation (PBS). Characterized organic materials showed higher N, P, and K contents in poultry droppings while cowdung had higher moisture and organic carbon contents. Irrespective of the type of organic materials, total P, organic P, available P and other forms of P increased significantly (p<0.05) with increasing levels of organic materials in both trials. In the first trial, total P and organic P increased at 60 days of submergence and declined afterwards while available P progressively increased up to 90 days of submergence, saloid P and aluminum bound P progressively decreased up to 90 days of submergence while iron and calcium bound P were highest at 60 days of submergence. In the second trial, total P and organic P progressively decreased with time while available P decreased at 60 days of submergence, saloid, aluminum and iron bound P were highest at 60 days of submergence. This implies that the use of poultry droppings in the soils of Geriyo irrigation project may ensure the supply of phosphorus to sustain rice production despite the seasonal flooding in the area with high risk of iron toxicity/ antagonism.