Solange Ndzeshala - Department of Soil Science, University of Nigeria, Nsukka, Enugu State, Nigeria
Sunday Obalum - Department of Soil Science, University of Nigeria, Nsukka, Enugu State, Nigeria
Charles Igwe - Department of Soil Science, University of Nigeria, Nsukka, Enugu State, Nigeria

Purpose Scarcity of effective manures frustrates the adoption of organic-based soil fertility management in tropical agriculture. Cattle dung (CD) is hugely generated but underutilised due to its high carbon-nitrogen ratio and low mineralisation rate compared with poultry droppings (PD), hence the need to enhance CD's efficacy.Method Effects of CD utilisation options on fertility of sandy-loam Ultisols and maize growth were assessed under glasshouse conditions. Four options, CD in its cured form (CD), CD-derived biochar (BC), CD water-soaked CD fermentate (FM) and CD+urea (CDU), were assessed against cured PD and NPK-۱۵:۱۵:۱۵ as reference manure and fertilizer, respectively, using ۵-kg potted soils watered to and maintained at field capacity. Organic amendments were added at ۱۰-t-ha–۱ equivalents before sowing except FM added alongside CDU’s urea at ۲۵۰ kg ha–۱ equivalent after sowing. Also, NPK-۱۵:۱۵:۱۵ was added at ۴۰۰ kg ha–۱ equivalent after sowing.Results After ۹ weeks, BC, CDU and PD had similar effects on soil pH, organic matter, total N and available P which increased by ۴۹-۵۱%, ۳۰-۳۴%, ۲۰۰-۳۳۳% and ۱۶۴-۱۷۶%, respectively relative to the control. The BC always showed maize plants similar to the tallest ones in PD. Maize dry matter was the highest in CDU/PD (۳۵.۰۶-۳۵.۵۶ g pot–۱) and the lowest in control (۹.۵۶ g pot–۱). Residual effects showed that BC and PD maintained the increases in soil pH, while CDU/PD always showed tallest plants and enhanced dry matter over the rest except BC. Soil pH, Mg۲+ and base saturation together caused ۹۳% of treatments’ effects on dry matter.Conclusion Converting CD to BC or supplementing it with urea (CDU) in coarse-textured tropical soils could have prolonged liming and/or biomass productivity-enhancing effects as PD.

Agronomic evaluation, Cattle-dung biochar, Liquid fermentate, Low-fertility tropical soils, Organic amend-ments, Urea addition