<p>This study evaluated how soil texture, moisture, and residue quality interact to regulate nitrogen (N) mineralization in tropical soils. A 182‑day greenhouse microcosm used a three‑factor factorial: two textures (loamy sand, clay loam), two moisture levels (− 300 kPa, &lt; FC; −33 kPa, FC), and four quality residues (high‑quality <i>Sesbania grandiflora</i> and <i>Indigofera hirsuta</i> (N 41 and 43, lignin 65 and 82, polyphenols 4 and 15 g kg^− 1; and low‑quality <i>Dipterocarpus tuberculatus</i> and <i>Eucalyptus camaldulensis</i> (N 5.6 and 6, lignin 86 and 145, polyphenols 28 and 108). Lowering soil moisture to − 300 kPa under <i>S. grandiflora</i> significantly increased NH₄⁺-N from 25.5 to 46.8 to 68.6–137.2 mg kg^− 1 in loamy sand and from 5.1 to 28.5 to 47.8–139.9 mg kg^− 1 in clay loam, while significantly decreased NO₃⁻-N from 76.5 to 131.0 to 11.1–34.2 mg kg^− 1 in loamy sand and from 88.2 to 249.6 to 42.5–166.5 mg kg^− 1 in clay loam, indicating nitrification inhibition by water deficit. Lower moisture also reduced net N immobilization in low‑quality residues in both soil textures. High‑quality residues yielded net N mineralization under both moisture regimes, whereas low‑quality residues initially immobilized N. In clay loam at FC, immobilization in low‑quality residues transitioned to net mineralization after 56 days after residue incorporation. N mineralization was driven by residue quality and its interaction with texture and moisture. High‑quality residues consistently enhanced mineralization; low‑quality residues transitioned from immobilization to mineralization in fine‑textured soil at FC. Water deficit suppressed nitrification and moderated residue effects.</p>