The impact of mineral fertilizer

Leaching can be a major problem in areas with high livestock, causing important nitrate surpluses that are hard to control.

Mineral nitrogen fertilizer, however, when accurately tailored to plant needs, does not contribute to leaching. Adjusting application rates to the economic optimum is the best strategy, both from an environmental and an economic point of view.

The economic optimum

Since it is the residual nitrate in the soil after harvesting that causes leaching, rather than the fertilizer applied in spring, it is important to reduce this residual nitrate pool.

The figure shows the impact of fertilizer application rates on residual nitrogen levels in the soil. Residual nitrogen remains stable up to a certain threshold of fertilizer application. If the threshold is exceeded, residual nitrate levels in the soil rise sharply. Lower fertilization rates does not reduce this, but drastically diminish grain yield. It is not surprisingly that this threshold coincides with the economic optimum. Applying more nitrogen than the plant can take up doesn’t make sense, neither economically, nor environmentally. Tailoring nitrogen application exactly to plant needs reduces the risk of leaching while optimizing grain yield.