Field Crop 2024, Vol.7, No.2, 79-92 http://cropscipublisher.com/index.php/fc 82 In summary, IAP significantly improves maize yield through optimized nutrient management, enhanced soil health, and better agronomic practices, outperforming traditional farming methods and contributing to sustainable agricultural productivity. 4 Nutrient Use Efficiency (NUE) in Maize 4.1 Definition and importance of NUE Nutrient Use Efficiency (NUE) in maize refers to the ability of the plant to utilize available nutrients, particularly nitrogen (N), to produce biomass and grain yield. NUE is a critical parameter in agricultural systems as it directly impacts crop productivity and environmental sustainability. High NUE means that a greater proportion of the applied nutrients are taken up and used by the crop, reducing the potential for nutrient losses to the environment through leaching, volatilization, or runoff (Figure 2) (Zhou et al., 2019; Shiade et al., 2023; Yadav et al., 2023). Figure 2 Interactions between nitrogen dynamics and environmental factors (Adopted from Yadav et al., 2023) Image caption: This diagram illustrates the comprehensive dynamics of soil nitrogen cycling. Sunlight, ambient temperature, and extreme weather events directly impact the nitrogen cycle. Crop rotation, tillage operations, plant species, and irrigation influence nitrogen cycling through soil incorporation and crop residues. Fertilizer application directly adds nitrogen sources, while biological nitrogen fixation converts atmospheric nitrogen into usable forms through microbial activity. Soil pH, temperature, salinity, texture, cation exchange capacity (CEC), aeration, and moisture content affect soil microorganism activity and organic matter decomposition, thus impacting nitrogen dynamics. Ultimately, the nitrogen cycle results in nitrogen uptake, emission, and leaching (Adopted from Yadav et al., 2023) 4.2 Challenges in achieving high NUE Achieving high NUE in maize is fraught with several challenges. One of the primary issues is the inefficient use of nitrogen fertilizers, which often results in significant environmental pollution and increased greenhouse gas emissions (Yadav et al., 2023). Factors such as soil fertility, climatic conditions, and inappropriate agronomic practices can further complicate the efficient use of nutrients. For instance, excessive or poorly timed fertilizer applications can lead to nutrient losses and reduced NUE (Zhang et al., 2018; Li et al., 2019; Zhou et al., 2019). Additionally, the genetic variability among maize cultivars in their ability to uptake and utilize nutrients poses another challenge (Yadav et al., 2023). 4.3 Strategies for improving NUE Several strategies have been proposed and tested to improve NUE in maize. Integrated Agronomic Practices (IAP), which include optimal planting density, split fertilizer application, and subsoiling tillage, have been shown to significantly enhance NUE by promoting greater dry matter and nitrogen accumulation. The use of integrated
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