About » NITROGEN AND PHOSPHORUS CYCLE IN AGRO-ECOSYSTEMS

Agro-ecosystems are very specific fauna and flora systems shaped bythe agricultural activities carried out at specific abiotic conditions(air, soil, water). They function in rural settings subject to heavyanthropopression, but also strongly interact with the natural ecosystems(trophic networks, gene exchange) and can be referred to as'semi-natural' ecosystems. 

Under such conditions, full andbalanced circulation of a chemical compound can hardly take place, andis substituted with open, highly simplified bio-geo-chemical cycles. Byhuman interference focused on accomplishing specific productionperformance, the cycle of biogenic elements in agro-ecosystems willalways involve higher or lower losses caused by the dominating positionof cultivated plants as producers, and the dominating role of human andfarm animals as consumers, as well as changes in the water balance(shortening and simplification of small local water cycle) accompanyingthe progressive natural landscape transformation into an agriculturallandscape. Anthropopression from non-industrialised and non-intensifiedagriculture makes room for specific self-regulating mechanisms,including the bio-geo-chemical balance of chemical elements.

Thingslook quite differently in large-scale and highly industrializedagricultural production - biogeocenoses and environmental formationsproduced by the intensive livestock industry are so heavily transformedand determined by the specifics of the agricultural activities(agricultural monocultures, highly specialized livestock production,separation of animal and crop production, production automation,large-scale interference with the growth and development process,reduced soil retention, degeneration of filtration conditions,accelerated ground water runoff, intensified leaching, heavymineralization of organic matter) that the ecosystems they form arecompletely artificial, and can be only preserved this way by heavy humaninterference.

As a result, there are many occasions for biogenicmatter losses, which leads to surplus nutrient volumes being introducedto the agricultural production cycle. 

The nitrogen cycle includes (based on Igras J. and Pastuszak M., 2009; all data on the example of Poland):

1. Nitrogen supply:

- Mineral fertilisers - 871,000 Mg N,

- Precipitation - 277,000 Mg N,

- Natural fertilisers - 550,000 N,

- Nitrogen fixed by symbiotic bacteria - 92,000 Mg N,

- Feed and by-products -263,000Mg N,

- Seed grains - 39,000 Mg N,

2. Nitrogen run-off:

- Main products - 781,000 Mg N,

- By-products - 263,000 Mg N,

- Seed grains - 39 Mg N,

3. Nitrogen losses:

- Ammonia emissions from livestock production - 400 Mg N,

- Ammonia losses from arable land - 40 Mg N,

- Nitrogen losses in oxidised products (gases) (N2, N2O) - 749 Mg N,

- Nitrate runoff to groundwater and surface water - 220 Mg N.

Nitrogenbalance (1,009,000 Mg) indicates that a significant surplus ofnitrogenis supplied to agricultural holdings in Poland. Note that a considerableshare of nitrogenlost from the agriculture is supplied to sea water.The remaining share isdenitrified as it drains to the surface water.

The phosphorus cycle in agro-ecosystems consists of the following elements:

1. Phosphorus supply:

- Mineral fertilisers - 137,000 Mg P,

- Natural fertilisers - 116,000 Mg P,

- Feed and by-products -61,000 Mg P,

- Seed grains - 11,000 Mg P,

2. Phosphorus run-off:

- Main products - 160,000 Mg P,

- By-products - 61,000 Mg P,

- Seed grains - 11,000 Mg P,

3. Phosphorus losses:

- Leaching from soil - 5.5 Mg P,

- Surface runoff from arable land - 18 Mg P,

4. Phosphorus accumulated in soil - 69,000 Mg P.

Likewise,the balance of phosphorus (92.500 Mg) indicates that a significantsurplus of this nutrient is supplied to agricultural holdings in Poland.Around 25% ofnitrogen and phosphorus supplied to the agriculture isestimated to reach theconsumers.

Biogenic matter discharges from the Baltic states (HELCOM, 2006)

 

Biogenicmatter input from the Baltic states contributing to eutrophication tothe Baltic Sea catchment area (HELCOM, 2004): Polska - Poland, Niemcy -Germany, Dania - Denmark, Szwecja - Sweden, Finlandia - Finland, Rosja -Russia, Łotwa - Latvia, Litwa - Lithuania.

Water and air erosion (N, P), surface run-off (nitrates), infiltration (nitrates) and emission from fertilisers (mainly NH3) and land (mainly nitrogen oxides), and precipitation are the main transfer routes of biogenic matter from the agriculture to the natural environment.

 

Federacja Zielonych GAJA
5 Lipca 45, 70-374 Szczecin, Poland
Phone. +48 91 489 42 33
Fax + 48 91 489 42 32
fzbiuro@gajanet.pl


Coalition Clean Baltic
Östra Ågatan 53
SE-753 22 Uppsala, Sweden
SHORT ABOUT THE PROJECT

Project Industrial animal farms in the Baltic Sea Region - sustainable practices to reduce nutrient loads is a part of a long-term campaign of the Coalition Clean Baltic and Green Federation "GAJA", aiming to reduce the negative impact of large-scale animal production on the environment and local communities in the Baltic Sea Region, particularly by reducing nutrient run-off into the sea. The project is part-financed by the European Union. This website reflects only the view of the Coalition Clean Baltic. The Executive Agency for Small and Medium-sized Enterprises (EASME) is not responsible for any use that may be made of the information it contains.