Nitrogen (N) is the most limiting nutrient for vegetable crop production, but anthropogenic sources pose risks due to its transformation into reactive forms and movement in the environment. Recent research on improving Nitrogen Use Efficiency (NUE) has focused on synthetic N application rates and crop growth under monocultures. However, the increasing use of diversified cropping systems, organic N sources, and alternative management practices makes it more challenging to understand N form transformation, movement, and crop uptake dynamics. A holistic approach to nutrient management is proposed, highlighting key management and production variables, as well as interactions at multiple levels, to improve the N cycle and NUE. Effective strategies include organic and inorganic N rate calibration, germplasm selection, crop rotations, nutrient interactions, and pest and water management. Agroecological practices such as vegetational diversification, integrated crop–livestock systems, conservation tillage, organic amendments, legume-based systems, and landscape nutrient management can improve NUE. Nitrogen is essential for plant growth and is involved in photosynthesis, protein synthesis, and chlorophyll production. N deficiency reduces transpiration, stomatal conductance, and photosynthetic enzyme activity. N-containing molecules like amino acids and nitric oxide play roles in plant defense and stress responses. Nitrate in the soil may serve as a signaling molecule, promoting lateral root growth and gene transcription. Overuse of anthropogenic N leads to environmental issues such as atmospheric reactive N deposition and pollution. Globally, about 120 million tons of N fertilizer are applied annually, with vegetables representing a unique case due to lower fertilizer input costs. Vegetable growers often overapply fertilizers to ensure yields, leading to lower NUE compared to lower-valued crops. NUE is influenced by factors such as soil fertility, cultivar, soil moisture, temperature, and pest infestations. The NUE of vegetable crops has been reported to be less than 50% in the 1970s, with improvements in the 1980s. NUE is determined by N uptake efficiency, utilization efficiency, and harvest index. Soil quality and NUE are affected by soil management, organic matter content, and microbial activity. Organic farming systems can provide a significant source of N, contributing to soil fertility and NUE. Cover crops and legumes can improve N mineralization and reduce N losses. Crop rotations and diversification can enhance N cycling and NUE by improving soil structure, organic matter, and nutrient availability. Agroecological practices such as organic farming, crop rotations, and integrated crop–livestock systems can improve NUE by enhancing soil fertility, reducing environmental losses, and promoting sustainable production. System diversification, including intercropping, alley cropping, and agroforestry, can improve N cycling and NUE by complementing resource use and enhancing system resilience. Integrated crop–livestock systems and aquaponics can improve NUE by recyclingNitrogen (N) is the most limiting nutrient for vegetable crop production, but anthropogenic sources pose risks due to its transformation into reactive forms and movement in the environment. Recent research on improving Nitrogen Use Efficiency (NUE) has focused on synthetic N application rates and crop growth under monocultures. However, the increasing use of diversified cropping systems, organic N sources, and alternative management practices makes it more challenging to understand N form transformation, movement, and crop uptake dynamics. A holistic approach to nutrient management is proposed, highlighting key management and production variables, as well as interactions at multiple levels, to improve the N cycle and NUE. Effective strategies include organic and inorganic N rate calibration, germplasm selection, crop rotations, nutrient interactions, and pest and water management. Agroecological practices such as vegetational diversification, integrated crop–livestock systems, conservation tillage, organic amendments, legume-based systems, and landscape nutrient management can improve NUE. Nitrogen is essential for plant growth and is involved in photosynthesis, protein synthesis, and chlorophyll production. N deficiency reduces transpiration, stomatal conductance, and photosynthetic enzyme activity. N-containing molecules like amino acids and nitric oxide play roles in plant defense and stress responses. Nitrate in the soil may serve as a signaling molecule, promoting lateral root growth and gene transcription. Overuse of anthropogenic N leads to environmental issues such as atmospheric reactive N deposition and pollution. Globally, about 120 million tons of N fertilizer are applied annually, with vegetables representing a unique case due to lower fertilizer input costs. Vegetable growers often overapply fertilizers to ensure yields, leading to lower NUE compared to lower-valued crops. NUE is influenced by factors such as soil fertility, cultivar, soil moisture, temperature, and pest infestations. The NUE of vegetable crops has been reported to be less than 50% in the 1970s, with improvements in the 1980s. NUE is determined by N uptake efficiency, utilization efficiency, and harvest index. Soil quality and NUE are affected by soil management, organic matter content, and microbial activity. Organic farming systems can provide a significant source of N, contributing to soil fertility and NUE. Cover crops and legumes can improve N mineralization and reduce N losses. Crop rotations and diversification can enhance N cycling and NUE by improving soil structure, organic matter, and nutrient availability. Agroecological practices such as organic farming, crop rotations, and integrated crop–livestock systems can improve NUE by enhancing soil fertility, reducing environmental losses, and promoting sustainable production. System diversification, including intercropping, alley cropping, and agroforestry, can improve N cycling and NUE by complementing resource use and enhancing system resilience. Integrated crop–livestock systems and aquaponics can improve NUE by recycling