Nitrogen (N) is the most critical element limiting agricultural production at a global scale. Despite many efforts, the N use efficiency (NUE) in agriculture remains in a range of less than 50%. Reaching targeted crop yields has resulted in N overuse, which is an economic and environmental concern worldwide. The continuous exploration of innovative solutions has led to the synthesis of novel nanomaterials, resulting in a powerful tool for the development of new technological products. Nanofertilizers are one of the most promising engineered materials that are being tested, either for soil or foliar applications. Encouraging results have been obtained using nanofertilizers in different plant species, however, limited information has been reported about its use in grasslands. Commonly, N is applied to grassland soils as granular fertilizers, which may result in significant losses via surface runoff or leaching, ammonia (NH3) volatilization and N oxides (N2O, NO, NOx) emissions. Nitrogen nanofertilizers are expected to increase NUE by improving the effectiveness of N delivery to plants and reducing N losses to the environment. Information on the efficiency of the use of N nanofertilizers in grasslands species is scarce and the application strategies that can be used to avoid N losses are poorly understood. New scenarios of increasing economic and environmental constraints may represent an opportunity for N nanofertilizers application in grasslands. This article reviews its potential use as an innovative approach to improve NUE and reduce N losses to the wider environment, analyzing potential shortcomings and future considerations for animal food chains.

The increase in global average temperature has significant implications for food security and agriculture production. Grass species adapted to new climate scenarios are essential for the success of livestock production. The aim of this study was to evaluate different forage species, providing animal feed during critical dry periods as an adaptation strategy for livestock grazing systems, and its implications for greenhouse gas (GHG) emissions. The field experiment was conducted during September 2015 to September 2017, with four treatments (n = 5, completely randomized block design), including two perennial forages, Bromus valdivianus (Bromus), Lotus corniculatus (Lotus), alone and in a mixture pasture (Br/L). As a control treatment, the forage species commonly seeded by the farmer was used (hybrid ryegrasses + Oat, Control). One-half of the plots was used for nitrous oxide (N2O) and methane (CH4) measurements, and the remaining half for destructive soil and forage sampling. Gas fluxes were measured using the static chambers technique. Cumulative emissions of N–N2O, C–CH4 and CO2−eq were not affected by treatments, averaging 1.7 kg N–N2O ha−1, 3.2 kg C–CH4 ha−1 and 635.5 kg CO2 ha−1, respectively (p > 0.05). However, emission intensity tended to be lower for Br/L compared with other treatments (p = 0.06) during the second year, while pasture yield was greater for Br/L (p < 0.05). The control showed a greater average pasture yield (first and second years) compared to other treatments, with the highest metabolizable energy and the lowest crude protein content. Our results suggest that a mix pasture Br/L as a management strategy would promote farm adaptation, given that it favors pasture yield at critical dry periods during the year. This inclusion also reduces N–N2O emissions from grassland soils as well as favoring C–CH4 capture. Our study determined that N–N2O and C–CH4 emissions were regulated by soil variables, mainly soil moisture and soil temperature. Extension and knowledge transfer should be provided to farmers to account for potential adoption barriers, such as low short-term yield.

Increasing rates of nitrogen (N) conventional fertilizer have led to increasing risks of N losses to the atmosphere, mainly as ammonia (NH3) and nitrous oxide (N2O). The aim of this study was to evaluate the effect of foliar N-based nanoformulations on the dynamics of N2O and NH3 emissions from grasslands. Six N treatments (50 kg N ha−1) plus a control (n = 4) were tested on a completely randomized design: granular urea (Urea-g), dissolved urea (Urea-d), dissolved ammonium nitrate (NH4NO3), and nitrate-, urea-, and ammonium-based nanoformulations (NO3-F, Urea-F, NH4-F) applied as foliar spray to intact soil cores maintained under controlled conditions. In addition, a control N = 0 was included. Cumulative emissions of N2O and NH3 (mg N m−2) were measured using dynamic/static chambers. Effects on yield and soil available N were also quantified. Volatilization of NH3 was the main N loss pathway (ranged from 2 to 51% of the N applied). Higher emissions were observed with NH4-F and low emissions in the nitrate-based fertilizers. Direct N2O losses were low compared to NH3 losses, varying between 0.07 and 0.25% of the N applied. Due to high NH3 losses, indirect N2O losses were 0.3 to 2.8 times greater than direct N2O losses. There was no effect of N treatments on soil available N or pasture yield. The application of a NO3-foliar formulation emerges as a potential alternative for the mitigation of integrated N gaseous emissions. Ammonium-based nanoformulations require improvements in order to reduce losses. Further studies should include yield evaluations under field conditions, cost–benefit analysis, and potential impacts in the agri-food chain.