Quantitative Analysis of Humic Substances in Soils Treated with Different Organic Manures in Sudano - Sahelian Savanna, Northeast Nigeria

This work was carried out to study the effect of organic manures on different fractions of soil organic matter. Field trials were carried out in 2008 and 2009 cropping seasons at the Teaching and Research Farm of the Department of Soil Science, University of Maiduguri, Maiduguri. The treatments consisted of three types of organic manures (cow dung, city refuse and poultry droppings) applied at three rates (0.0, 2.5, and 5.0 tons/ha). The three organic matter fractions; (human (HN), fulvic acid (FA) and humic acid (HA) were significantly affected by the organic manures and their rates. Poultry droppings increased HA and FA contents but had a decreasing effect on HN content. Humic acid (3.65 g/kg) and FA (52.05 g/kg) contents were highest in soils treated with 5.0 tons/ha of cow dung, while it had the lowest content of HN (885.9 g/kg). Fulvic acid was higher in all the soils than humic acid.