|HERRERA, JUAN - University Of Buenos Aires|
|RUBIO, GERALDO - University Of Buenos Aires|
|LEVY, LILIA - University Of Buenos Aires|
|LUCHO-CONSTANTINO, CA - University Of Buenos Aires|
|ISLAS-VALDEZ, SAMIRA - University Of Buenos Aires|
|PELLET, DIDIER - University Of Buenos Aires|
Submitted to: Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/13/2016
Publication Date: 4/19/2016
Citation: Herrera, J., Rubio, G., Levy, L., Delgado, J.A., Lucho-Constantino, C., Islas-Valdez, S., Pellet, D. 2016. Emerging and established technologies to increase nitrogen use efficiency of cereals. Agronomy. 6(2):25. doi:10.3390./agronomy6020025.
Interpretive Summary: A better understanding of the effects of N sources and management on the root systems of crops and how these effects relate to those on shoots is fundamental to developing better N fertilization products and management strategies that better synchronize crop N demand with N availability and thus maximize NUE. Similarly, a more deliberate account of plant physiological processes, including the diversity of mineral nutrient uptake mechanisms, their translocation and metabolism, has been suggested for the development of modern fertilizers (Bindraban et al., 2015). Such considerations may significantly improve the physicochemical delivery of nutrients, their composition, and the amount and timing of application to meet crop uptake needs. The fertilizer sources used nowadays have been approximately the same over the last 60 years. Throughout the world, additional funding for fertilizer research is needed to increase site-specific nitrogen use efficiencies across large, key agricultural regions of the world. Additional training and education is needed to develop future expertise across nations to apply nitrogen use efficiency research on the ground; Fugile et al. (2011) estimated that the fertilizer industry invests only 0.1-0.2% of its revenue in research and development, compared with about 10 and 17% by the seed and pharmaceutical sectors, respectively. The development of fertilizers has been driven by identifying cheap sources of plant nutrients. Although such characteristics are essential to produce affordable food, observance of knowledge of plant physiology could significantly benefit the development of new fertilizer sources (Bindraban et al., 2015). An example is producing fertilizers with formulations that include more than one nutrient. Antagonism may occur among most nutrients. With a mixture of nutrients, plants would preferentially transport more of one, inhibiting the uptake of others (Dimkpa, 2014; Yang et al., 2008). Synergism in nutrient uptake has also been demonstrated for N (Riedell et al. 2010) and other nutrients (Ma et al., 2014; Matula, 1996). Integrated N management strategies allow for the achievement of production goals while minimizing the risk of environmental pollution (Herrera and Delgado, 2010; Rathke et al., 2006; Vanlauwe et al., 2014). Sources of N and timing of application determine the most suitable method for application. The interest in implementing new knowledge about methods of application is stimulating the development of sensors to diagnose the N status of crops in real time throughout large areas. Decision support systems are, in this context, becoming fundamental to integrating several variables to optimize source, rate and method of application. Fig. 1 classifies the reviewed N technologies according to their degree of innovation and adoption. Among potential new technologies we identified the incipient development of nanofertilizers, nutrient based formulations to coat seeds, and recycled nutrients. In a context of increasing concern about the environmental consequences of N, innovations outside the farm such as more methods to manufacture N fertilizers that are more energy efficient and emit less CO2; constructed wetlands and buffer zones; and more effective regulations, will also shape in the long term the way N fertilization will be done in the future.
Technical Abstract: Nitrogen (N) fertilizers are expensive inputs; additionally, loss of N increases costs, contributes to soil acidification, and causes off-site pollution of air, groundwater and waterways. This study reviews current knowledge about technologies for N fertilization with potential to increase N use efficiency and reduce its negative effects on the environment. Classic fertilizer sources such as urea and ammonium sulfate are the major sources used, while slow N release fertilizers have not been significantly adopted for cereals and oil crops. Microorganisms, with the exception of Rhizobium sp. in soybeans, are also not widely used. The interest in implementing new N fertilization knowledge is stimulating the development of sensors to diagnose the N status and decision support systems for integrating several variables to optimize source, rate and method of application. Among potential new technologies we identified the incipient development of nanofertilizers, nutrient formulations to coat seeds, and recycled nutrients. Furthermore, increasing concern about the environmental consequences of N is likely to facilitate the implementation of innovations outside the farm, such as methods to manufacture N fertilizers that are more energy efficient and emit less CO2; constructed wetlands and buffer zones; and more effective regulations for N fertilization.