Crop yield losses have escalated worldwide due to extreme and/or prolonged drought periods as well as insufficient irrigation. In the cold and arid regions of northern China, the difficulty of straw decomposition is a regional problem, which is undoubtedly aggravated by the increasingly serious drought. Thus, the combination of a reasonable grain feed rotation mode and tillage mode of straw returning is an effective measure to solve this problem. This study set up a grain forage rotation (in the first year, it is used for grain production, and the straw is returned to the field after the grains are harvested; when the entire plant is harvested in the second year, it is used as feed) and two treatments for straw returning and no straw returning to the land characterized by two different water degresses (include drought stress and normal irrigation). To clarify the impact of returning straw to the field on the soil improvement and drought tolerance of various maize varieties, the effects of straw returning on the agronomic traits, hormones, osmotic adjustment substance content, whole plant fresh weight, and dry weight of six different maize varieties (MC703, A2636, DK 159, ZQ 1, 303 × 178, and ZJ 330) under drought stress were analyzed. The data showed the following: (1) After straw returning, the soil moisture content increased by 3.55–14.70% and the soil bulk density decreased by 0.73–5.23% under the drought stress treatment, and the soil physical condition became closer to the ideal value. (2) After straw returning, the plant height, ear height, stem diameter, fresh weight, and dry weight of the maize whole plant under the drought stress treatment increased by 0.95–7.70%, 4.70–15.71%, 0.31–9.33%, 2.67–36.23%, and 3.72–38.60%, respectively. (3) After straw returning, the abscisic acid, ethylene, soluble sugar, and soluble protein in the leaves under the drought stress treatment decreased by 7.92–21.42%, 8.03–3.37%, 0.63–22.98%, and 2.37–9.17%, respectively. Straw returning significantly alleviated the damage caused by drought stress to the growth and development of maize, and promoted the growth and development of maize under the drought treatment. The results of this study provide a theoretical basis for a high and stable yield of grain crops in arid areas.

Maize (Zea mays L.) is a major cash and food crop in China and is critical to national food security. Straw returning improves soil physical properties by reducing bulk density and increasing porosity, while phosphate fertilization enhances soil P availability; their combined application can improve soil fertility and structure, creating favorable conditions for high yield. To evaluate this, we conducted a three-year field experiment (2023–2025) in the Tumochuan Plain irrigation area (Midwestern Inner Mongolia, China) with maize cultivar ‘Xianyu 335’. A control treatment (CK) without straw management and without phosphate fertilization was included for comparison. We examined the effects of two straw management practices (straw incorporation with deep tillage, SF; and surface straw mulching under no tillage, FG) and four phosphate fertilization rates (0, 80, 100, and 120 kg P₂O₅/ha) on photosynthetic characteristics, chlorophyll fluorescence, dry matter accumulation, and yield. S and P main effects were significant for all measured traits, including Fo; however, the S × P interaction was not significant for Fo, Fm, Fv/Fm, Ci, and yield. Compared with CK, all straw management treatments improved photosynthetic and chlorophyll fluorescence traits, increased dry matter accumulation, and enhanced grain yield. Straw incorporation with deep tillage consistently outperformed surface straw mulching under no tillage, and increasing phosphate fertilization rates enhanced the positive effects. Among the tested treatments and under the partial-budget assumptions, SFP120 (120 kg P₂O₅/ha) gave the highest yield (14,781.53 kg/ha), while SFP100 (100 kg P₂O₅/ha) had the numerically highest net profit (17,743.33 yuan/ha, ≈2546.17 USD/ha), 21.19 yuan/ha (≈3.04 USD/ha) above SFP120 (17,722.14 yuan/ha, ≈2543.15 USD/ha).