Effect of Dose and Date of Application of Vermicompost and Its Combination with N-Fertilizer on Maize Grain Yield

The European Union produces about 58 million tons of grain maize annually, and although Slovakia contributes only a small share, grain maize is an important crop occupying 10.6% of the country’s arable land. A two-year pot experiment was conducted to evaluate the effects of vermicompost (Vc) dose and application timing, applied alone or in combination with mineral nitrogen fertilizer, on maize grain yield and selected grain-quality parameters. The spring pre-sowing Vc application at 170 kg ha−1 total N proved appropriate. Increasing the Vc dose from 170 to 340 kg ha−1 total N did not significantly influence grain yield, thousand kernel weight (TKW), or the contents of crude protein and starch. When soil was fertilized with Vc in autumn, the spring application of mineral N at 60 kg ha−1 resulted in higher grain yield compared with the spring application of Vc at 170 kg ha−1 total N. Application of Vc alone, regardless of dose or timing, did not affect starch content or TKW. The combined use of mineral and organic nitrogen sources appears to be the most effective strategy for maize nitrogen nutrition. Applying Vc in autumn or spring at 170 kg ha−1 total N, followed by 60 kg ha−1 mineral N in spring, created favorable conditions for achieving high grain yield and quality.