Investigating the Effect of Fertility Management on Plant Parasitic Nematodes and Maize Yield under Long-Term Continuous Cropping in Northern Guinea Savanna of Nigeria

The intensification of maize production, a major staple in Nigeria, has adversely affected soil quality particularly in the mono-cropped Northern Guinea savannah ecologies. Continuous intensive cropping has adversely affected soil quality and crop yield thereby threatening the sustainability of intensified maize-based systems in the Northern Guinea savanna of Nigeria. A field study was carried out at Zaria under a long-term maize trial established in 1997, to evaluate the effect of soil fertility amendments on plant parasitic nematodes and yield of maize. The experiment was laid out in a randomized complete block design. The treatments were made of urea fertilizer, animal manure, Centrosema pascuorum, Vigna unguiculata and applied to make 45 and 90 kg N ha-1 used as either sole or mixed fertilizer treatments. Results obtained showed that incidences of plant parasitic nematode infection were significantly reduced between 3.4 - 80% in soil by the mixed application of urea fertilizer and animal manure compared to sole urea application at 90 kg N ha-1. With the application of 45 kg N urea + 45 kg N animal manure (7.5tons ha-1 cow dung or 1.5tons ha-1 poultry litter), maize yield was not significantly different from yields obtained at 90 kg N sole urea fertilizer application, suggesting that manure improved the soil quality, reduced use of urea fertilizer and attained statistically similar yield level with 90 kg N sole urea fertilizer to be seen as a better soil fertility management strategy. Principal component analysis indicated that plant parasitic nematode genera Pratylenchus and Aphelenchoides sp. influenced grain yield negatively, but their dominance in the soil was identified as one of the yield-reducing factors. The study showed that Pratylenchus and Aphelenchoides parasitic nematodes were significantly contributing to grain yield decline, and this was indicated in the principal component analysis. Higher numbers of Aphelenchoides in legume-amended treatments reflects the fact that Aphelenchoides is a legume-parasitic nematode. To maximize maize productivity in the Northern Guinea savanna of Nigeria, adoption of a “balanced” fertilization that combines urea fertilizer with animal manure to restore or maintain optimal crop yield for long - term soil productivity is recommended.