NOTES ON METHODOLOGY
Source and methods of data collection
Data present nitrogen and phosphorus inputs and outputs on utilised agricultural area, nitrogen and phosphorus gross surplus, nitrogen emissions into the air and nitrogen net surplus.
Data on fertilisers, number of livestock, production and harvested area are the result of statistical surveys in the field of crop and livestock production:
· the Survey on Land Sown and Crops at the End of Spring Sowing (PO-22)
· the Survey on Actual Yields of Early Crops and Fruits (PO-32)
· the Survey on Actual Yields of Late Crops, Fruits and Grapes (PO-33)
· the Survey on Autumn Sowing (PO-21)
· the Survey on Yields of Citrus Fruits and Olives (PO-34)
· the Annual Survey on Livestock (PO-51)
Data on nitrogen emissions in the air have been taken over from the Ministry of Economy and Sustainable Development.
In cooperation with the Faculty of Agriculture in Zagreb, according to calculated coefficients, expert estimates for the amount of nitrogen and phosphorus in seeds and planting material, nitrogen biological fixation, nitrogen atmospheric deposition, harvested crops and fodder have been made.
Nitrogen inputs comprise nitrogen in all forms entered into the soil with seeds and planting materials, fertilisers, biological fixation, atmospheric deposition and crop residues.
Nitrogen outputs comprise nitrogen in all forms extracted from the soil in harvested crops, in harvested or grazed fodder and in crop residues removed from the field.
Gross surplus (nitrogen) is nitrogen inputs less nitrogen outputs. The surplus of nitrogen in the soil represents the negative influence of agriculture on the environment.
N emissions are the quantity of nitrogen emitted into the air as a result of agricultural activity.
Net surplus is gross surplus reduced by the N emissions into the air. It represents the remaining nitrogen in the soil and the part of nitrogen that can potentially be leached and contaminate the water.
Phosphorus inputs comprise phosphorus in all forms entered into the soil with seeds and planting materials, fertilisers and crop residues.
Phosphorus outputs comprise phosphorus in all forms extracted from the soil in harvested crops, in harvested or grazed fodder and in crop residues removed from the field.
Gross surplus (phosphorus) is phosphorus inputs less phosphorus outputs. The surplus of phosphorus in the soil presents a negative influence of agriculture on the environment.
- no occurrence