The long-term utilization of inorganic fertilizers in pakchoi cultivation can result in increased nitrate levels, potentially posing health risks to human consumers. For this study, we investigated the efficacy of organic fertilizers as a promising alternative for enhancing soil structure, improving fertility, and increasing the yield of pakchoi. A two-year field trial was conducted from 2022 to 2023 to examine the effects of the combined application of organic fertilizer on the growth and yield of pakchoi. Three types of irrigation water, namely fresh water (F), brackish water (B), and magnetized–ionized brackish water (MIB), were used in combination with five different organic fertilizer rates (0, 20, 40, 60, and 80 kg/ha, denoted as 0, 1, 2, 3, and 4). The results revealed that treatments F2, F3, B2, B3, and MIB3 significantly improved the growth indexes of pakchoi. Notably, treatments F3, B3, and MIB3 resulted in an earlier onset of the fast growth period for leaf area index and fresh weight. During this period, we observed the highest cumulative growing degree days (ΔCGDD) values, which were 628.36 °C for plant height (MIB4), 475.01 °C for leaf area index (B3), 259.73 °C for fresh weight (B3), and 416.82 °C for dry matter accumulation (B3). The logistic model indicated an increase in eigenvalue at an organic fertilizer application rate of 60 kg/ha, while excessive fertilization had inhibitory effects. Under brackish water irrigation, both plant height and leaf area index demonstrated significant positive effects on yield, with plant height having a particularly noteworthy direct effect at a coefficient of 0.935. MIB water irrigation demonstrated superior advantages for promoting pakchoi growth, leading to significantly higher rates of fresh weight and dry matter accumulation compared to traditional brackish water irrigation. The maximum value of each growth index exerted a significant direct influence on its respective growth parameter, whereas ΔCGDD demonstrated a relatively smaller or potentially negative effect. Applying organic fertilizer appropriately can assist in the production of pakchoi and provide a scientific basis for increasing yield.

The issues of limited water availability and excessive fertilizer utilization, both of which negatively impact soil health and crop productivity, are key focal points in the pursuit of sustainable agricultural progress. Given these crucial obstacles, it is crucial to utilize accurate methods of irrigation and fertilization in order to improve the condition of the soil and promote the progress of sustainable farming. The objective of this research is to determine the optimal indicators for creating a minimal data set (MDS) that can assess the influence of organic fertilizers on the quality of pakchoi soil in varying irrigation water sources. Principal component analysis and norm values were utilized to create the MDS, and its accuracy was confirmed by examining coefficients of Nash efficiency and relative deviation. The results of our study showed that there was not much difference in soil bulk density (BD), but there was moderate variation in soil water content (SWC), soil salt content (SSC), alkali-hydrolyzed nitrogen (AN), available phosphorus (AP), available potassium (AK), and organic matter (OM). The selected MDS indicators included BD, AN, and OM. The soil quality index (SQI) achieved a high R² value of 0.952, indicating a strong correlation. Furthermore, the nonlinear evaluation model showed a high level of effectiveness and efficiency, with E_f and E_r values of 0.899 and 0.046, respectively. The effectiveness of this model in evaluating soil quality under different irrigation water conditions is evident. Notably, treatments involving magnetized–ionized brackish water (average SQI = 0.524) and the application of 20 kg/ha organic fertilizer (average SQI = 0.719) demonstrate the capacity to enhance soil quality. The present study presents a pragmatic, productive, and economical quantitative evaluation approach that can be used for worldwide vegetable farming with the utilization of clean water, saline water, magnetized–ionized saline water, and organic manure. Thus, we encourage vegetable growers to consider adopting both magnetized–ionized brackish water and organic fertilizers, and the utilization of the nonlinear soil quality index evaluation model is recommended as it offers a sensitive and effective approach to assessing soil quality across various irrigation and organic fertilizer schemes.

Water and nitrogen management are crucial for food security and the efficient use of water and fertilizer, especially in arid regions. Three irrigation levels, namely, 80% crop water requirement (ET_C) (W1), 100% ET_C (W2), and 120% ET_C (W3), and three nitrogen application levels, namely, 0 kg/ha (N1), 207 kg/ha (N2), and 276 kg/ha (N3), were used as the experimental treatments, and a control group, denoted as CK, was created. The results show that the maximum height achieved was 82.16 cm under W3N3. There was a single-peak variation trend throughout the growth stages of SPAD. It peaked at 58.44 under W3N3 and then at 27.9 under W2N2. The net photosynthetic and transpiration rates displayed bimodal peaks and the phenomenon of a “photosynthetic midday depression”. And the prominent peaks in leaf water use efficiency occurred at 14:00 and 18:00, alongside noteworthy enhancements observed under the W3 treatment. Water and nitrogen and their interactions significantly affected the dry matter (DM) of winter wheat, with the spike accounting for the highest percentage. The W2N2 treatment demonstrated superior effectiveness in enhancing winter wheat water use efficiency, offering the potential to decrease irrigation requirements by 20% and nitrogen application by 25%. Moreover, the maximum PFPN attained under W2N2 reached 60.13, representing a noteworthy 35.25% increase compared to the control group (CK), but the HI of the W2N2 treatment only reached 0.56. The highest HI was achieved with W3N2 (0.73), and the nitrogen application of 207 kg/ha was more conducive to obtaining a higher HI. The highest yield was achieved under W3N3 (13.599 t/ha), followed by W2N2 (12.447 t/ha), and the spike proportion exceeded 60% with W2N2, and its production cost and economic benefit ratio of under 0.31 were superior to those for other treatments. Multiple regression analysis revealed that the maximum yield reached 12.944 t/ha with an irrigation amount of 3420.1 m³/ha and a nitrogen application of 251.92 kg/ha. Overall, our study suggests using an optimal water–nitrogen combination, specifically an irrigation level of 2829 m³/ha and a nitrogen application rate of 207 kg/ha, leading to increased winter wheat yields and economic benefits. These research results provide a pragmatic technique for improving winter wheat production in southern Xinjiang.