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Title: MORPHOLOGICAL AND CHEMICAL PROPERTIES OF SELECTED SLUDGE AMENDED NIGERIAN SOILS

Author
item MBILA, M - IOWA STATE UNIVERSITY
item THOMPSON, M - IOWA STATE UNIVERSITY
item MBAGUWU, J - UNIVERSITY OF NIGERIA
item LAIRD, DAVID

Submitted to: Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/14/2003
Publication Date: 9/15/2003
Citation: Mbila, M.O., Thompson, M.L., Mbaguwu, J.S., Laird, D.A. 2003. Morphological and Chemical Properties of Selected Sludge Amended Nigerian Soils. Soil Science. 168(9):660-669.

Interpretive Summary: Fertilizers are needed to increase food production in Nigeria and other tropical regions but are often too expensive for local farmers. Where available, sewage sludge has the potential to serve as an inexpensive source of plant nutrients. Much work has been done on understanding the impact of sewage sludge applications on properties of temperate region soils, but little work has addressed the impact of sewage sludge application on tropical soils. We discovered that after 37 years of sewage sludge applications on a low fertility soil in Nigeria that both the ability of the soil to retain plant nutrients and the total amount of plant nutrients retained by the soil had substantially increased. The amount of organic matter in the soil had also increased. The study demonstrates that sewage sludge applications have a positive impact on tropical soils, unless the sludge contains high levels of heavy metals. This study will help governmental agencies in tropical regions to better regulate sewage sludge applications on agricultural lands. The study will also help U.S. foreign aid workers to better extend knowledge developed in temperate regions about sewage sludge applications to tropical regions where the information is needed.

Technical Abstract: Sewage sludge application to agricultural lands is one way to address the high demand for and low supply of commercial fertilizers in Nigeria. This study was conducted to determine the changes in morphological and chemical properties of a sludge-amended soil. Two pedons on a 5-ha sewage farm and one control pedon were selected for the study. The control pedon was a Nsukka sandy loam (coarse-loamy, kaolinitic, isohyperthermic Rhodic Kandiustult). Sludge amendment increased the exchangeable bases, total soil C and N, and the cation exchange capacity (CEC) of the amended soils compared with the control soil. Sludge amendment also promoted biological activity and greater aggregate development. After more than 37 years of sewage-sludge amendment, the base saturation of the subsurface horizons had changed enough to warrant reclassification of the sludge-amended soils from Ultisols to Alfisols.