The spring mung bean-summer sweet maize cropping system can alleviate groundwater scarcity problems on the North China Plain. However, the effects of nitrogen application on water use efficiency (WUE) and economic benefit of spring mung bean-summer sweet maize cropping system remain unclear. This study investigated the crop yield, economic benefit and WUE of spring mung bean-summer sweet maize cropping system under four N application regimes: N0, no N for spring mung bean and summer sweet maize; N1, 60 and 60 kg·ka⁻¹ N for spring mung bean and summer sweet maize, respectively; N2, 60 and 120 kg·ka⁻¹ N for spring mung bean and summer sweet maize, respectively; and N3, 60 and 180 kg·ka⁻¹ N for spring mung bean and summer sweet maize, respectively. The results indicated that N application significantly increased annual maize equivalent yield (MEY), and N1 and N3 increased annual MEY by 8.6% and 10.7% (p < 0.05), respectively, compared to N0 in 2021. N application significantly influenced evapotranspiration (ET) in spring mung bean and summer sweet maize seasons (p < 0.05). N1 and N2 decreased ET by 15.1% and 18.9%, respectively, in spring mung bean season, and increased ET by 14.4% and 18.8%, respectively, in summer sweet maize season compared to N0 in 2021, respectively (p < 0.05). N3 improved annual WUE by 10.2% and 11.4% compared to N0 in 2020 and 2021, respectively (p < 0.05). Also, experimental year significantly affected MEY, ET and WUE in spring mung bean and summer sweet maize seasons, and annually (p < 0.001), which can be attributed to the variations in seasonal rainfall between the two experimental years. In summary, N application increased grain yield and WUE of spring mung bean-summer sweet maize cropping system, however, a lower N application rate was recommended to achieve a balance between economic benefit and WUE on the North China Plain.

To address the challenges of large model size, limited detection accuracy and poor adaptability to complex environments in tomato leaf disease detection tasks, this paper proposes a lightweight and efficient detection method based on an improved YOLO11n. First, a dynamically refined intersection over union loss function is introduced to optimize bounding box regression quality across different training stages. Subsequently, an adaptive multiscale fusion module is designed to enhance feature extraction adaptability to varying scales. To further strengthen spatial perception across lesions of different sizes, a progressive receptive field via dilated convolutions module is proposed. Finally, a detail enhanced detection head is incorporated to improve detection performance on small-scale and blurred-boundary disease regions. Extensive experiments validate the effectiveness of the proposed approach, achieving a 2.1% improvement in mean Average Precision at an Intersection-over-Union (IoU) threshold of 0.5 (mAP50) and a 2.9% improvement in mean Average Precision (mAP) averaged over Intersection-over-Union thresholds from 0.5 to 0.95 (mAP50–95) compared with the YOLO11n baseline, while boosting inference speed to 482 frames/second. The proposed method demonstrates excellent accuracy, real-time performance and lightweight deployment capability, providing a novel technical solution and practical support for intelligent agricultural disease detection.

Ultisol, characterized by acidic pH and low fertility index, present significant challenges for crop productivity. This study investigated the efficacy of three biochar types, oil palm empty fruit bunches (OPEFB-B), rice husk and maize cob (MC-B) applied at 10 t·ha^–1, with varying incubation periods (0, 10, 20 and 30-d) with three replicates, to enhance Ultisol fertility index and cucumber performance. A factorial randomized complete block design was used, which was conducted in farmer fields in Medan, Indonesia from June to October 2023. This investigation used the cucumber hybrid Metavy F1, cultivated in a composite sample of randomly collected Ultisol. Following analysis of variance, significant means were separated by Duncan’s multiple range test at a 5% level, and correlations among the variables were evaluated. Soil fertility index (SFI) of Ultisol was established and classified. Results demonstrated that MC-B was superior in boosting cucumber yield to 47.4 t·ha⁻¹. This increase is attributed to a significant elevated in the uptake of nitrogen, phosphorus and potassium by about 125%. In contrast, OPEFB-B was most effective at improving Ultisol SFI by 0.447 (a 38.8% increase). An incubation period of 20-d was identified as optimal for maximizing yield and nutrient uptake. The interaction between biochar type and incubation periods were significant effect on plant height and leaf area. Specifically, the combination of OPEFB-B with 10- or 20-d incubation enhanced soil fertility and increased the N and K content in plant shoots. Correlation analysis revealed significant positive associations between cucumber productivity and key soil properties: organic C, cation exchange capacity, base saturation, and exchangeable Ca and K with values of 0.321, 0.342, 0.420, 0.392 and 0.487, respectively. Synergistic improvements in soil fertility and crop yield require the extended incubation period of MC-B and OPEFB-B, applied separately or in combination.