Combined application of amino acid compound fertilizer and sulfur enhances yield, nutrient use efficiency, and starch accumulation in waxy maize

Sulfur (S), an essential secondary nutrient, plays a crucial regulatory role in crop yield and quality. A two-year field experiment (2023–2024) was conducted with four treatments: no fertilizer (CK); sulfur fertilizer (SF, 75 kg S ha−1); amino acid compound fertilizer (AACF, N/P/K = 225/75/75 kg ha−1); and combined application of amino acid compound fertilizer and sulfur (AACF + S, N/P/K/S = 225/75/75/75 kg ha−1). The measured parameters included leaf area index (LAI), SPAD values, yield and its components, dry matter accumulation and translocation, nitrogen (N) and sulfur (S) accumulation and translocation, nutrient uptake and use efficiencies, and major grain compositions. Results indicated that treatment AACF + SF significantly outperformed the other treatments across most indicators. Compared to SF, the two-year average grain yield and dry matter accumulation at maturity (R6 stage) in AACF + SF increased by 24.9 % and 9.8 %, respectively; in comparison to AACF, these increases were 11.8 % and 4.1 %. Path analysis identified grain number per ear as the key yield determinant. Furthermore, compared to AACF, AACF + SF significantly enhanced nitrogen use efficiency (NUE) by 6.2 %, nitrogen agronomic efficiency (NAE) by 36.1 %, and nitrogen partial factor productivity (NPFP) by 5.1 %. In comparison to SF, AACF + SF enhanced sulfur use efficiency (SUE) by 5.9 %, sulfur agronomic efficiency (SAE) by 178.8 %, and sulfur partial factor productivity (SPFP) by 13.2 %. Additionally, compared to CK, the two-year average grain starch content increased by 3.1 %, 9.9 %, and 14.1 % under SF, AACF, and AACF + SF, respectively. This study offers a scientific and practical fertilization strategy for achieving high-yield and high-quality production of waxy maize.