# Using an Uptake Enhancer to Mitigate Nitrogen Leaching While Enhancing Uptake Efficiency
## 1 Introduction  
Nitrogen is a critical element for plant growth and plays a pivotal role in various physiological processes. As a result, its availability often limits plant productivity. Consequently, mechanisms of N uptake and acquisition have garnered a lot of research interest. The plant's ability to absorb and assimilate N can have a profound influence on a range of growth and development traits. For example, N application substantially affects agronomic traits in oats, such as plant height, grain yield, and milling quality [1]. Nitrogen is crucial for plant growth and development as it is a key component of amino acids, proteins, cell walls, membranes, and nucleic acids [2, 3]. Moreover, N is linked to chlorophyll formation, the green pigment responsible for photosynthesis, which enables plants to harness sunlight and convert it into energy-rich compounds. Its deficiency leads to stunted growth, reduced photosynthesis and leaf area, accelerated senescence, and decreased productivity. As an essential nutrient, N is central to plant metabolism, being present in vital organic compounds, including amino acids, proteins, nucleic acids, and phytohormes. Despite N being one of the most abundant elements on Earth (especially as atmospheric N gas (N\({}_{2}\)) in the atmosphere), N deficiency is the most prevalent nutritional problem affecting crops worldwide [4]. One of the causes of limitations in N is the remarkably high nutritional requirements by plants, as N is the most abundant nutrient inmost plant tissues [5]. Plants absorb N in the inorganic form either as nitrate (NO\({}_{3}\)\({}^{-}\)) or ammonium (NH\({}_{4}\)\({}^{+}\)) [6]. However, there are low inorganic N levels in the soil and a high fraction of soil N in organic form, which is inaccessible to plants and thus contributes to N deficiency [7]. In fact, only 0.00024% of N on Earth is considered accessible for plant usage [5]. Plants often face challenges due to living in dynamic and complex ecosystems [8], which in turn impact their N uptake. Several environmental factors, such as precipitation, temperature, wind, soil type, and pH, affect N uptake. These stressors have a negative impact on N assimilation in the plant tissues, lower N uptake, and greatly decreased crop yields. For assimilation, nitrate needs to be reduced into ammonium ions, followed by its assimilation into amino acids. This reduction occurs in roots as well as shoots. In contrast, ammonium is less mobile in the soil and can be directly absorbed into amino acids [9]. The ratio of these two types of N and how readily they are absorbed by the soil have a big impact on N uptake efficiency. To achieve adequate crop production levels and meet global food demands, 85-90 million metric tons of N fertilizers are added annually to the soil [10]; consequently, the global demand for agricultural N fertilizer continues to escalate [11]. On the other hand, plants have poor N absorption, absorbing only 40-50% of a given amount or even less [12; 13; 14]. The remainder is dissipated into the wider environment, contributing to a range of ecological and human health effects [15; 16; 17]. Nitrogen transported to freshwater from agricultural soils is estimated to be 39-95 Tg yearly [18]. Furthermore, N-based fertilizers are thought to be the worst polluters of water. Excessive N fertilizer application has economic and ecological expenses in addition to the tremendous environmental consequences of fertilizer production. The sources of N used in fertilizers are linked to oil prices, and the more volatile the oil market is, the more the fertilizer price fluctuates [19]. As a result, N fertilizer is costly to produce and is the second most expensive input for farmers after fuel, resulting in significant economic losses. Thus, it is evident that crop uptake must be enhanced to ensure long-term agricultural production. Less fertilizer N may be required if fertilization is carefully managed, yet grain yields and protein may be maintained or improved [20].