Objectives The uneven rainfall during the maize growing season in the southwest region affects the growth and yield of maize. We studied the cultivation techniques of using integrated water and fertilizer technology and increasing maize planting density to achieve increased yield and efficiency in maize production.

Methods From 2023 to 2024, a field experiment was conducted in Mianyang, Sichuan Province, using the maize cultivar ‘Zhengdan 958’ as the experimental material. The treatments were composed of two planting densities: 9×10⁴ plants/hm² (D1) and 6×10⁴ plants/hm² (D2), and three water and fertilization methods: artificial fertilization with no irrigation (FM), multiple topdressing through drip fertigation (HM), and artificial fertilization under drip irrigation (WM). The leaf area index and dry matter accumulation at the pre- and post-silking stages were investigated. The yield and yield components were examined at the harvest stage, and the nitrogen (N) uptake and nutritional quality were analyzed. The irrigation water use efficiency (IWUE), nitrogen partial productivity (NPP), as well as the total income and profit were calculated.

Results At D1 and D2 densities, the HM treatment demonstrated significantly higher yield, dry matter accumulation during maturity, harvest index, leaf area index during silk emergence, and NPP than the WM and FM treatments over the two years, and the above indexes of the D1HM treatment were significantly higher than those of the D2HM treatment. Although the yield and NPP of the D1WM treatment were higher than those of the D2WM treatment, the yield difference between the WM and FM treatments varied by year (P<0.05), and the stability of the yield increase decreased. The yield and other indicators of the FM treatment at the D1 density were higher than those at the D2 density in 2023, but there was no significant difference between D1 and D2 in 2024, indicating that traditional planting techniques cannot exert the yield-increasing effect of increasing density. The IWUE of the HM treatment increased by 28.56% and 15.33%, respectively, compared to the WM treatment under D1 and D2 density conditions. Compared to FM, the average total income of the HM and WM treatments increased by 36.25% and 12.31%, and the economic profit increased by 49.87% and 22.66%. Compared with WM, the total income and economic profit of the HM treatment increased by 8.86% and 10.6% on a two-year average.

Conclusion Under dense planting conditions, topdressing fertilizer through drip irrigation can significantly improve the leaf area index, dry matter accumulation, and harvest index of maize, thereby increasing grain yield, water and fertilizer utilization efficiency, and economic benefits. It is difficult to achieve a significant increase in maize yield by simply increasing planting density or improving irrigation conditions. Therefore, promoting the integrated technology of dense planting and drip fertigation in the southwest region of China is an effective measure to further enhance the regional agricultural comprehensive production capacity and efficiency.