Maize Yield, Apparent Nitrogen Recovery, and Soil Microbial Responses to Organic Amendments Under a Plant-Derived Inhibitor-Based Fertilization System

Improving crop nitrogen (N) recovery while maintaining soil health is essential for sustainable maize production. Although plant-derived inhibitors can regulate soil N transformations, their combined effects with organic amendments remain unclear. In a maize field experiment established in 2020 in northeast China, we evaluated six fertilization treatments using crop performance from the 2024 growing season and soil samples collected at the 2024 harvest: an unfertilized control (CK), conventional fertilization (NF), NF plus 2-cyclopenten-1-one (CCO; NFC), and NFC combined with biochar (NFBC), maize straw (NFSC), or pig manure (NFOC). Relative to NF, apparent N recovery efficiency (REN) under NFC increased by 12.21 percentage points (a relative increase of 29.2%). The incorporation of organic amendments further increased grain yield to 15.50–15.89 t ha−1, improved soil physical properties, enhanced nutrient availability and microbial biomass, and shifted bacterial and fungal community compositions. Metagenomic analysis revealed increased abundances of genes associated with nitrification, denitrification, and dissimilatory nitrate reduction to ammonium under NFSC and NFOC, whereas NFBC showed limited changes relative to NFC. Amendment type thus appears to shape the functional response under CCO. Biochar plus CCO combined high maize productivity with high apparent N recovery, indicating its potential for sustainable N management.