Field Crop 2024, Vol.7, No.2, 79-92 http://cropscipublisher.com/index.php/fc 83 soil-crop system management (ISSM) that combines organic and inorganic fertilizers has also been effective in achieving sustainable high maize yields and improved NUE (Wang et al., 2020). Moreover, adopting precision farming techniques, such as site-specific nitrogen management and the use of enhanced efficiency fertilizers, can help in optimizing nutrient application and reducing losses (Yadav et al., 2023; Shiade et al., 2023). The integration of crop-livestock systems (ICLS) has also been found to improve nutrient cycling and soil chemical attributes, thereby enhancing NUE in paddy fields (Denardin et al., 2020). Lastly, modern breeding and biotechnological tools, including gene-editing technologies, offer promising avenues for developing maize cultivars with improved nutrient utilization capacities (Yadav et al., 2023). By implementing these strategies, it is possible to achieve higher maize yields while minimizing the environmental impact of agricultural practices. 5 Effect of IAP on NUE 5.1 Influence of IAP on NUE Integrated Agronomic Practices (IAP) have been shown to significantly enhance Nitrogen Use Efficiency (NUE) in maize cultivation. The implementation of IAP, which includes optimal planting density, split fertilizer application, and subsoiling tillage, has demonstrated substantial improvements in both maize grain yield and NUE under varying soil fertility conditions. For instance, a study found that IAP increased maize grain yield by 25%-28% in low soil fertility fields and by 36%-37% in high soil fertility fields over two growing seasons. This increase was attributed to greater dry matter and nitrogen accumulation, which were promoted by increased leaf area index and root length, leading to higher soil mineral nitrogen content and post-silking nitrogen accumulation (Zhao et al., 2019). Moreover, long-term studies have shown that combining inorganic and organic fertilizers under an integrated soil-crop system management (ISSM) strategy can achieve sustainable high maize yields and improved NUE. Over an 11-year period, ISSM increased maize yield by 27% compared to traditional farmers' practices, while also reducing nitrogen surplus and losses, thereby enhancing NUE (Wang et al., 2020). Similarly, integrated nutrient management practices, which include the use of farmyard manure and biofertilizers along with recommended doses of inorganic fertilizers, have been found to improve maize growth and yield significantly (Sailaza and Kannamreddy, 2019). 5.2 Case studies Several case studies highlight the effectiveness of IAP in improving NUE: Northeast China: An 11-year field study demonstrated that ISSM, which combines inorganic and organic fertilizers, achieved 97.7% of the yield obtained with high-yielding practices while significantly reducing nitrogen losses and greenhouse gas emissions. This approach resulted in higher NUE and better sustainability compared to traditional practices (Wang et al., 2020). North China Plain: A four-year study on double cropping of winter wheat and summer maize showed that integrated agronomic practices management (IAPM) improved grain yield and nitrogen balance. The treatment that combined optimized tillage, plant density, and fertilization practices resulted in the highest nitrogen recovery efficiency and reduced nitrogen loss by 39.1%-54.4% compared to other treatments (Liu et al., 2018). Pakistan: A field study on the maize-wheat cropping system found that integrated nutrient management (INM) with 75% of the recommended dose of NPK fertilizers supplemented with biochar significantly improved dry matter production, grain yield, and nutrient uptake. This approach also enhanced the economic sustainability of the cropping system (Sarwar et al., 2023). 5.3 Mechanisms enhancing NUE The mechanisms through which IAP enhances NUE are multifaceted and involve several physiological and agronomic factors:
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