The primary purpose of fertilisation is to satisfy the nutritional needs of the plants to the extent that high yields of good quality can be achieved. The secondary function is to maintain an optimum (average) nutrient content in the soil.

Nutrient deficiencies reduce yields and the quality of plant products. Balanced nutrition of all nutrients is essential for proper development and plant outcome. A deficit of any macro- or even micro-nutrient limits yield and reduces the efficiency of utilisation of other nutrients.

The application of fertilisers over the actual needs decreases the efficiency of fertilisation and leads to the losses of components due to their movement beyond the borders of cultivated fields and beyond the reach of the plant root system. “Leakage” of mineral nutrients means actual financial losses for the farmer and simultaneously poses a threat to the aquatic environment in particular. The most troublesome elements in the respect mentioned above are nitrogen and phosphorus. At the same time, they are the elements with the most substantial yield-forming effect, so their dosage should be precisely adjusted to the plant nutritional requirements and plant growth conditions.

To avoid nutrient depletion, they should be applied in such quantities as the plants will take up. Therefore, it is advisable to plan fertilisation based on a nutrient balance, i.e., the field surface balance method. Given that the input of nutrients to the soil from all sources (that we can quantitatively identify) should balance the need for fertilisation. The sources of inputs and how fertilisation needs are determined depend on the nutrient under consideration. In all cases, the primary sources of nutrients are mineral, natural and organic fertilisers, while the significant element of fertilisation needs is the plant nutritional demands.

Procedure for calculating mineral nitrogen fertilizer application rates – simplified nitrogen balance

  Mineral nitrogen dose – farm yield [t/ha] x plant nitrogen uptake [kgN/ha] (acc. to table 10)
– the sum of nitrogen from other sources x fertilizer equivalent – correction for plants grown
after fodder crops or Fabaceae intercrops (according to the table below) / 0.7
(coefficient of nitrogen use from mineral nitrogen fertilizers)

Quantitation of residual active nitrogen after a faba bean crop

Phosphorus and potassium balance (pdf in polish)

Important information

• Balanced nutrition of all nutrients is essential for proper plant development and yield
• A deficiency of any macro- or even micro-nutrient limits yield and reduces the efficiency of the other nutrients consumption
• The components must be applied in such quantities that the plants completely take them up
• The plant nutritional demands are a key component of fertilisation needs