For years the declared goal of the European Union, formalized in the legislative packages Green Deal and Farm to Fork Strategy, has been to restructure society and economy towards sustainability and ultimately climate neutrality. To achieve this, agriculture, which is both a producer of CO2 and a victim of climate change, must shoulder some pretty big tasks. The EU has planned that it will become climate neutral well before other sectors and take on additional tasks as a CO2sink. Mineral fertilization is regarded as one of the parameters for saving greenhouse gases. In this context, the Commission would like the total level of nitrogen losses to be halved and the total fertilizer use to be reduced by 20 %; the final figures are still an issue of contention. These objectives are to be achieved by 2030, in other words within eight years.
Every kilo counts
On the subject of fixed reductions, the EU Nitrogen Expert Panel (EUNEP) disagrees with the EU Commission. The EUNEP is a European network in which experts in science, politics, industry and agriculture from nine European countries cooperate. Founded in the autumn of 2014, the organisation considers a different approach is more appropriate: In order to effectively prevent nitrogen losses, it believes it is wiser to improve the efficiency of the fertilizer used. Thus for every kilo of nutrients supplied, the greatest possible amount of return must be obtained.
The experts are convinced that a high nitrogen fertilizer, which achieves a high return in the field is just as efficient as a lower nitrogen fertilizer that achieves a lower return.
The task which the EUNEP sees here is not to reduce the quantity of fertilizer overall, but to increase the effectiveness of the fertilizer applied. Even faced with the significant increase in the price of fertilizer, every farmer can only agree with this, because every kilo counts for farm efficiency.
An indicator of efficiency
The panel of experts has formulated its objective as follows: The more of the nitrogen applied that leaves the field with the harvested crop, the better. Both for the farmer and for the environment. To determine the efficiency of fertilization measures as accurately as possible, the EUNEP has developed an indicator for this: Nitrogen Use Efficiency (NUE). The value, expressed as a percentage, offsets the N input and output of a system. A system can have very different orders of magnitude. For example, it can be a single field, a farm or an entire state.
The NUE is calculated as a ratio of the nitrogen applied – including mineral and organic fertilizer, N surpluses and biological N fixing – and the quantity of nitrogen removed from the field: N removal divided by N supply times 100 gives the NUE in percent. To compare previous developments, the EUNEP experts calculated the NUE for the EU and for the individual member states for the years 2009 to 2015. Averaged over this period, the indicator was 64% in the EU. The value for Germany was the same, France achieved 72%.
The panel members believe that an optimal NUE should be between 75% and 90%. Below this threshold, too much of the applied nitrogen is lost, the crops thus absorb too little of it. There can be many reasons for this effect. The important point is: Too low an NUE harms both the environment and the operating results. On the other hand, a value that consistently exceeds 90% could certainly be achieved with efficient cultivation systems like Precision Farming. However, this value means that too much nitrogen is being removed from the field with the harvest. Consequently too little nitrogen remains on and in the soil; the result would inevitably be excessive humus depletion and the loss of soil fertility.
The entire system under the microscope
So how can the NUE indicator be raised from its current average of 64% in Germany to the desired range? This calls for sophisticated cultivation and production methods, for which the entire cultivation system must be put under the microscope. Farmers, industry and science are faced with the task of consistently applying all known measures for nitrogen efficiency and searching relentlessly for new parameters. The latter certainly includes breeding, which in future will make available varieties with a high degree of nitrogen utilization.
But also the well-known but in practice frequently underestimated methods of good agricultural practice contribute to putting optimally healthy and well supplied plants onto or into the field, which are capable of turning every kilo of nitrogen into yield and quality. These measures naturally include ensuring the best possible soil structure through conservative tilling and the supply of lime for an optimal pH value, as well as a timely and demand-based distribution of the nitrogen.
Sulphur ensures efficiency
A very important element is the balanced nutrition of plants, in other words supplying them with essential and secondary nutrients as well as trace nutrients. Vital, well-supplied plants are healthier and more resistant and thus better able to absorb nitrogen and process it effectively.
In this context, sulphur is particularly important because nitrogen and sulphur are closely linked in plant metabolism. If sulphur is missing, uninterrupted nitrogen uptake is no longer possible. This results in reduced resistance to diseases and pests and falling protein content. By contrast, if sulphur is integrated into the fertilization strategy according to the requirements of the crop, it boosts the nitrogen utilization of the plants and ensures the production of high-quality protein compounds.
