Regulation No. 38 on requirements and procedure for keeping accounts of nitrogen and phosphorus input into the soil and output from the soil.

This Ministerial Regulation establishes requirements and a procedure for calculating the nitrogen and phosphorus balance in agricultural soil. The nutrient balance is determined by calculating the difference between total inputs and total outputs in kilograms per hectare. Inputs comprise nitrogen and phosphorus from seeds, mineral fertilizers, and organic fertilizers, as well as atmospheric nitrogen fixation by legumes and legume-based catch crops. Outputs consist of nutrients removed from the soil through the harvest of main crops, by-products such as straw, and undersown crops. Specific mathematical formulas for both nitrogen and phosphorus balances are provided.
The Regulation requires that calculations be performed annually by 31 March for the preceding calendar year’s growing cycle. This requirement applies to fields referred to in the Water Act. The calculated data are recorded in the field book. The annexes provide reference tables indicating the nitrogen and phosphorus content of different crops and plant parts, as well as values for nitrogen fixation by leguminous crops and catch crops.