Mineral fertilisation should only supplement the nutrients already available in the soil according to the needs of the plants and not replace soil fertility.
The application of mineral fertilisers can aim to:
- improve plant development,
- increase crop yields,
- regulate soil pH,
- extend the plant growing season,
- enrich the crop with necessary nutrients.
Each of the fertilisers used, due to the elements they contain, is responsible for achieving specific objectives. For example, nitrogen fertilisers are primarily responsible for increasing plant yield through growth and better plant development. The mechanism of action of nitrogen fertiliser in the plant is to convert it into amino acids necessary for protein synthesis, which directly translates into achieving better growth and yield.
It is essential to know what fertilisation and in what doses our soil needs. Excessive use of mineral fertilisers leads to over-fertilisation of the soil, often to its salinisation, which results in soil deterioration, e.g. through the extinction of useful microbial groups. Excess fertilisers result in nutrients leaching into the groundwater and reduce the profitability of production. The optimum economic effect, resulting from the relationship between fertiliser costs and yield, is achieved with a yield slightly lower than the maximum that can realistically be achieved.
In order to correctly determine the amount of mineral fertilisation for individual elements, it is necessary to base this on the results of soil tests and the real abundance of the soil, comparing it to the needs of the planned crop. The calculation should also take into account the fertiliser value of organic fertilisers. It is necessary to take into account the moisture content of the soil, the conversion time of the fertilisers to the form taken up by the plant, as well as leaching by water. The basis of wise fertilisation, however, is to achieve a soil pH close to neutral, as only then will most agricultural plants be able to make optimal use of the fertilisers applied. Thus, a fertiliser balance should be drawn up for each field, which is a separate scenario, to enable optimum soil fertilisation and crop nutrition, without the risk of over-fertilisation and over-application.
In agricultural practice, the importance of mineral fertilisation is very often overestimated, while organic fertilisation is underestimated or neglected. The soil is sometimes treated merely as a place for sowing crops, without considering the importance of its fertility, which directly leads to the degradation of organic matter and, as a result, to a continuous increase in inputs while yields decrease.
For more details on fertilisation, see Area 7: Nutrient Management.