Prospects of Enhancing Cattle-Dung Manure’s Effectiveness by Partial Substitution with Poultry Droppings-Compost Mix for Slash-and-Burn Managed Tropical Soils

Abstract

Use of animal manure-based soil amendments may offset the detrimental effects of slash-and-burn practice by smallholder farmers. Cattle dung is relatively more abundant but mineralizes slower and hence less effective than poultry droppings which can be made even more effective by co-application with the more readily mineralized compost. This study evaluated the potential of a 50% substitution of the slow-release cattle dung with a mix of equal volumes of poultry droppings and fruit-waste compost (CD:PD&FWC) for restoring the fertility of slash-and-burnt tropical soils on the growth of mung bean as a test crop. Screenhouse soil fertility trials were carried out utilising slash-and-burn managed sandy-loam Ultisols from a Nigerian rainforest, with soil properties showing slight improvement over the unburnt soil. Treatments were CD:PD&FWC (10 t ha^–1), cattle dung (10 t ha^–1), NPK-15:15:15 (125 kg ha^–1), and unamended control. At the termination of crop growth after 10 weeks, CD:PD&FWC showed the highest soil pH (5.86), soil organic matter (33.70 g kg^-1), total nitrogen (2.00 g kg^–1), available phosphorus (25.15 mg kg^–1), and cation exchange indices. Soil content of exchangeable acidity showed a reverse trend with lowest values from CD:PD&FWC (0.36 cmol kg–1) and highest from NPK- 5:15:15/control (1.10 cmol kg^–1). Cattle dung gave longer plant roots than CD:PD&FWC, but the two produced higher root dry matter (2.74-3.27 g pot^–1) than NPK-15:15:15/control (0.70 g pot^–1). The CD:PD&FWC gave taller 10-week-old plants (30.69 cm), more root nodules (415) and higher shoot dry matter (37.80 g po^t–1) than cattle dung; NPK-15:15:15/control gave the lowest (14.77 cm, 26-37 and 5.95 g pot^–1, respectively). The CD:PD&FWC and, to lesser extents, cattle dung improved soil fertility and mung bean growth. Organic amendment CD:PD&FWC is, therefore, preferred to sole cattle-dung manure for improving the productivity of slash-and-burnt acid coarse-textured soils of the humid tropics.