Achieving the goal of increasing both crop yield and water-use efficiency with a better irrigation regime is a major challenge in semi-arid areas. In this study, we presented a two-season field experiment (October 2018–June 2019 and October 2019–June 2020) that considered drought stresses, i.e., no irrigation (W0), irrigated in jointing (W1), both in jointing and flowering (W2) after re-greening, and wheat varieties (S086; J22). The results showed that a 45.5% excess of irrigation water input did not promote wheat yield (W1 vs. W2). S086 was beneficial for the usage of soil water consumption under a low amount of irrigation water in both seasons. In addition, irrigation positively affected the activities of superoxide dismutase and catalase in flag leaves (p < 0.05). A decrease in irrigation helped to increase the concentrations of soluble sugar and proline and decrease the amount of malondialdehyde content for S086. For the water- and irrigation-water-use efficiency, W1 was significantly increased by 20.6–21.7% and 38.3–39.3% in 2018–2019 and 23.4–24.4% and 43.8–44.7% in 2019–2020, respectively, as compared to W2. Additionally, a higher yield for S086 than J22 was found under deficit irrigation. Consequently, our study suggested that the S086 variety combined with a total amount of irrigation water of 165 mm might be recommended to meet the win–win goal of high crop yields and water-use efficiency for reducing ground water depletion in the future.

Water resource shortage and unreasonable application of nitrogen (N) fertilizer have been problems in wheat production of northern China. However, the interaction effects of water regimes and N practices on wheat root growth, grain yield, soil water, and inorganic N changes as well as water-N use efficiency are still unclear under drip irrigation. A field experiment was conducted during the 2020–2021 and 2021–2022 winter wheat (Triticum aestivum) growing seasons. In this study, three irrigation schedules (i.e., irrigation was applied up to 80% [D1], 75% [D2], and 70% [D3] as soon as the soil water content decreased to 65%, 60% or 55% of field capacity) and two N practices (i.e., N applied at the base, jointing, booting stages were 90, 72, 48 kg ha⁻¹ [N1], and the base, jointing, booting, filling stages were 90, 40, 40, 40 kg ha⁻¹ [N2], respectively) were considered. The decease in irrigation water amount was offset by the increase in soil water consumption. In addition, N practices significantly interacted with irrigation on soil NO₃⁻–N accumulation (2021–2022), NH₄⁺–N accumulation, SPAD value (2020–2021), N content in stems and grains at maturity, and average root length and weight density at the flowering stage. Irrigation, rather than N practices, significantly affected grain yield, total N uptake, crop N transformations (NT), the contribution of NT to grain (NTPC), water and N productivity, in which, for the value of these two seasons, D2 increased total N uptake by 18.1% (p < 0.05), and NT by 39.4% (p < 0.05) under N1 as compared to D3. Additionally, the highest WUE and ANUE were found in D2 during 2021–2022. Heavy irrigation water amount caused high a LAI; further analysis proved that the LAI was the key factor affecting grain yield, and positively and significantly correlated to yield. However, no significant difference in the LAI between D1 and D2 was found. N1 was beneficial to prevent N leaching and increase water and N use efficiency, biomass, and N transformation amount. This study recommends that D2 + N1 might be a promising system for manipulating irrigation and fertilization practices under sub-surface drip irrigation systems to improve water and N use efficiency and grain yields in semi-arid regions.

An intensified farming system can significantly increase crop productivity but can also cause major groundwater overdraft for irrigation and the loss of crop diversity. It is imperative to develop alternative crop rotations beyond the simplified conventional winter wheat–summer maize (W–M) rotation for alleviating the groundwater over-extraction in China’s Huang-Huai Plain. This study systematically quantified crop water requirement (ET_c) and irrigation water requirement (ET_aw) of eight crops from 2013 to 2018 based on the SIMETAW model applied to the Shangqiu area in the Huang-Huai Plain. Fourteen crop rotations (CI (i.e., crop harvests per rotation cycle year) 1.5 or 2) were constructed based on the ROTAT model. Results showed that compared to W–M rotation, the alternative rotations (CI = 1.5) significantly reduced the annual ET_c in wet, normal, and dry years by 9–21%. Replacing winter wheat in the double cropping system did not significantly decrease annual ET_c. Wheat–soybean rotation had similar annual ET_c and ET_aw accompanied by higher economic output and equivalent yield about 1.2 times, with 9% more protein output than the W–M rotation. There were eight crop rotations having greater comprehensive evaluation index (CEI) than W–M rotation by Entropy-TOPSIS when considering 10 indicators including water requirements, yield, economic benefits, water use efficiency, energy, and nutritional values. Spring potato–summer soybean had the highest CEI of 0.627. Sweet potato and potato showed advantages when included in rotations by increasing yield. “Wheat–soybean”-based rotations (CI = 1.5) also performed well in profitability and protein output. Replacing summer maize with soybean is promising for profitability and nutrition output without increasing irrigation requirements. Therefore, decreasing the cropping index, or involving soybean or sweet potato in rotations can be a useful way to improve sustainable land use, save water, and ensure food products in this water stressed region.

Circular agriculture is an inevitable trend in the sustainable development of global agriculture. At present, there are issues such as insufficient utilization of resources, serious land pollution, and lack of technical support in circular agricultural ecological parks. This study explores the safe application of organic fertilizer to field crops within circular agricultural ecological parks. A peanut (Arachis hypogaea L.)–wheat (Triticum aestivum L.)–maize (Zea mays L.) crop rotation system was selected to research safe application methods of biogas residues on the peanut–wheat–maize crop rotation system. In this experiment, we set up different amounts of biogas residues as the base fertilizers, with no fertilizer and only chemical fertilizer treatments serving as controls. We determined the yield, quality, heavy metal content, and nutrient uptake of wheat, maize, and peanuts, as well as soil nutrient content and heavy metal content under different biogas residue application rates. The results of the experiment are as follows: (1) Biogas residue as a base fertilizer increased the yield of peanuts, wheat, and maize. The highest yield for each crop occurred when the biogas residue amount was 67,500 kg hm⁻², with yield increases of 36.7%, 26.6%, and 14.1% for peanuts, wheat, and maize, respectively, compared to the no fertilizer treatment. (2) The application of biogas residue improved the seed quality of peanuts, wheat, and maize. The B3 treatment showed strong quality improvement potential, increasing peanut crude protein content by 3.92–7.48%, soluble sugar content by 36.99–49.70%, crude fat content by 0.95–3.27%, wheat crude protein content by 2.22–8.72%, soluble sugar content by 6.21–8.51%, maize crude protein content by 2.87–3.61%, and soluble sugar content by 21.62–28.05% compared to the control. (3) The application of biogas residue enhanced the uptake of nutrients by crops and increased the contents of effective nutrients in the soil. (4) The application of biogas residue did not cause excessive accumulation of heavy metals in crops and soil. In conclusion, the application of biogas residue positively impacts crop growth, quality, and soil health in circular agricultural ecological parks, and has potential in agricultural production systems. Future research should focus on determining the optimal ratio of organic and chemical fertilizers, their efficient use, and the mechanisms by which organic fertilizer application can increase crop yield and quality, as well as improve soil quality.

Drip fertigation has been adopted to conserve water resources and improve water-nitrogen use efficiency. However, the optimal irrigation level and nitrogen