A new pathway for better fertilization technologies
The amount of CO2 in the atmosphere has increased more than 20% in less than 40 years, and representing well over 50% of the total increase in atmospheric CO2 since the start of the industrial revolution. The changes in climatic conditions must alter the crop cultivation practices in many areas, chief of which is N management in agroecosystems.
In managed agricultural systems, most, if not all of the inorganic N is provided in the form of nitrate, and since the intensive agriculture is dominated by monocultures, these systems have already low N use efficiency as fertilized plants take up less than half of the N applied. In addition, C3 plants spend approximately 25% of their total energy in shoots and roots for the assimilation of nitrate. To mitigate this energy expenditure, they employ a mechanism called photorespiration, which supplies a significant part of the energy for nitrate assimilation. The elevated CO2 is however reducing photorespiration and thereby currently preventing efficient nitrate assimilation that causes reduction in food quality.
This means as atmospheric CO2 concentrations rise, the value of the plant material as food that rely on nitrate as their primary source of Nitrogen will diminish unless novel methods are implemented.
The main two N forms to which the plants have access (ammonium and nitrate) have different physiological effects on plant growth and development. Organic N acquisition of plants via ammonium as N source leads to higher protein concentrations in C3 crops under elevated CO2. So, the differential effects of N forms suggest that it might be possible to maintain food quality and yield while significantly decreasing the N input into cropping systems.
The increased CO2 concentration in the atmosphere and its relationship with the N assimilation now presents a new opportunity in developing novel N fertilizer technologies that focus on ammonium utilization, bypassing energy demanding nitrate assimilation mechanism.