One of the reasons for recasting the regulation: From the perspective of legislators, the nitrate concentration in groundwater is often too high. The authorities believe that agriculture contributes to this. If nitrate is not absorbed by plants, it can be washed out in the rain. This is the case, for example, if too much is fertilised or at the wrong time. Therefore, in future, the amount of nitrogen should be adjusted as accurately as possible to the needs of the plants, and kept as low as possible. In other countries, legislators dictate this. In addition, the Fertiliser Ordinance obliges German farmers to produce an exact nutrient balance for their fields.
Useful consequence of genetic variation
"It means that maximising the efficient use of nitrogen by plants plays an even greater role than before," states maize breeder Thomas Presterl from KWS. But how do you keep the yield stable, when many fields will receive less nitrogen in the future? "Of course, no plant can manage without a certain amount of nitrogen, it is one of the most important plant nutrients," says Presterl. "But our research has shown that some maize plants absorb nitrogen more efficiently than others. This is the result of natural genetic variation," explains his colleague Roland Peter, also an expert in maize breeding at the independent plant breeding company.
As a result, nitrogen-efficient varieties show superior performance with a low supply of nitrogen, compared to other varieties. Nitrogen-efficient varieties still have a decent yield even under deficiency conditions: "A variety should use the plant-available nitrogen in the soil as efficiently as possible from the beginning of growth, before it is shifted into deeper layers or released into the air. The most important requirement is that maize varieties with limited fertilisation do not suddenly drop sharply in their yield, but maintain a high level of performance," explains Presterl. Yield security is one of KWS’ priority breeding objectives.