Comparative Effects of Poultry Manure and NPK Fertilizer under Plastic Mulch on Plant-Parasitic Nematodes and Yield of Two Cucumber Varieties

Abstract

Plant-parasitic nematodes (PPNs), particularly Meloidogyne spp., severely constrain cucumber (Cucumis sativus L.) production in tropical regions, causing substantial yield losses. The use of synthetic nematicides is constrained by environmental concerns, resistance, and regulatory limitations, necessitating integrated, low-toxicity alternatives. This study compared the effects of poultry manure and NPK fertiliser under plastic mulch on plant-parasitic nematodes and the yield of two cucumber varieties. A completely randomised block design was employed with three treatments: plastic mulch + NPK fertiliser, plastic mulch + poultry waste, and plastic mulch only (control), each replicated three times. Two cucumber varieties (African Giant F1 and Smart F1) were assessed over one cropping cycle. Parameters measured included baseline and post-planting soil and root nematode densities, soil physicochemical properties, growth traits, and yield components. Pre-planting sampling recovered 294 PPNs from 15 genera (density 29.40 per 10 g soil), with Meloidogyne spp. being dominant (17.69%). Poultry waste contained significantly higher nitrogen, phosphorus, potassium, moisture, and electrical conductivity than the experimental soil (p < 0.001). Post-planting, both enrichment treatments reduced soil and root nematode populations relative to the mulch-only control, with poultry waste generally producing the strongest growth and yield responses. Meloidogyne spp. remained the most abundant genus, followed by Scutellonema spp. Poultry waste produced the highest plant heights, stem girths, fruit set, fruit length, and fruit weight in both varieties. Plant-parasitic index (PPI) values indicated that communities were dominated by c-p 3 taxa, typical of moderately disturbed agricultural soils. Within the plastic-mulched production system evaluated, the enrichment treatments were associated with lower nematode abundance than the mulch-only control, while poultry waste generally produced the highest growth and yield measurements. Because no unmulched treatment and no cost-benefit analysis were included, the independent effect of plastic mulch and the economic superiority of the treatments cannot be determined from this study.