194
J. Kubiak and S. Machula
infiltration conditions, and facilitation of surface runoff of rainwater [28]. In addition, the accelerated outflow of groundwater intensifies the process of soil leaching
[36, 37]. As a result, the export of nutrients from the catchment to surface waters
is increasing [38]. The drainage of agricultural land, due to the increased mineralization of organic matter, especially on organic soils, increases the load of nutrients
discharged into the water bodies.
Agricultural land use is a source of nitrogen and phosphorus for waters. In Finland,
it was found that N and P losses from agricultural areas are 10–20 times higher than
from non-human areas [39]. The losses of 0.05 kg P ha
−1 during the year [40]
are considered natural for the catchment of the Swiss lakes, and for the basin of
southern Sweden—losses amounting to 0.06 kg P ha
−1 during the year [41]. Kajak
[12] described the export of nutrients from the Wisła basin at the level of 5 kg N ha
−1
during the year and 0.3 kg P ha
−1 during the year. In agricultural catchments, no
more than 0.5 kg of P ha
−1 are leached to surface waters over the course of the year;
in the case of nitrogen, losses amount to several kilograms per 1 ha [40]. The average
annual loss of fertilizer components from the catchment of coastal rivers—in the case
of mineral nitrogen at 1.00–1.30 kg NNH4+NO3 ·ha
−1 , and in the case of phosphorus at
0.20 kg P 2 O 5 ·ha
−1 . Annually, soil losses in the bottom moraine landscape in Western
Pomerania amounted to 23.9 kg P 2 O 5 ·km
−2 [42]. Durkowski [43] described them
at the level of 4% of the applied fertilizer dose, while every year from intensely
fertilized agricultural areas it amounts to a maximum of 5.5 kg N·ha
−1 and 0.6 kg
P·ha
−1 . According to Lossowa [10], 1–5% of phosphorus and 10–20% of nitrogen
introduced into the soil with mineral fertilizers is washed away into the surrounding
waters. In the Wisła basin from area sources (mainly from agricultural areas), 52%
of nitrogen and 45% of phosphorus come from the Odra catchment—43 and 30%
respectively [44].
The catchments of the studied lakes were intensively used for agriculture. In
the vast majority, these areas belonged to state-owned farms, using very intensive
fertilization of up to 750 kg NPK·ha
−1 [36], exceeding the national average (180–200
kg·ha
−1 ) [40]. In the period from 1979/1980 to 1992/1993. There was a decline in
the country scale, mineral fertilization (on average from 193 to 66 kg NPK·ha
−1 ,
and on individual farms even up to 61 kg·ha
−1 agricultural land) [45]. A similar
tendency was observed in Western Pomerania—in the mid-1970s, fertilization with
mineral fertilizers averaged about 280 kg·ha
−1 , by the end of the eighties it ranged
between 250–280, and in 1992–1993 there was a sharp decrease in fertilization to 63,
1 kg·ha
−1 [46–48]. Since the mid-1970s, the use of lands did not change in this part
of the country—arable lands usually occupied about 400, meadows—from 85 to 90,
pastures—from 37 to 38, and forests—from 265 to 270 thousand. ha. In the 1990s,
the eutrophication of lakes could inhibit a significant reduction in fertilization [15].
It should be noted, however, that large point sources, including municipal sewage,
may outweigh the impact of agriculture on a given basin [2, 3].
Inadequate water and sewage management in rural areas is an important cause
of water eutrophication. At the same time, along with the expansion of water
supply systems, sewage must be taken over and treated. Otherwise, not only rapid
degradation of lakes will occur, but also deterioration of groundwater quality [7, 10].
J. Kubiak and S. Machula
infiltration conditions, and facilitation of surface runoff of rainwater [28]. In addition, the accelerated outflow of groundwater intensifies the process of soil leaching
[36, 37]. As a result, the export of nutrients from the catchment to surface waters
is increasing [38]. The drainage of agricultural land, due to the increased mineralization of organic matter, especially on organic soils, increases the load of nutrients
discharged into the water bodies.
Agricultural land use is a source of nitrogen and phosphorus for waters. In Finland,
it was found that N and P losses from agricultural areas are 10–20 times higher than
from non-human areas [39]. The losses of 0.05 kg P ha
−1 during the year [40]
are considered natural for the catchment of the Swiss lakes, and for the basin of
southern Sweden—losses amounting to 0.06 kg P ha
−1 during the year [41]. Kajak
[12] described the export of nutrients from the Wisła basin at the level of 5 kg N ha
−1
during the year and 0.3 kg P ha
−1 during the year. In agricultural catchments, no
more than 0.5 kg of P ha
−1 are leached to surface waters over the course of the year;
in the case of nitrogen, losses amount to several kilograms per 1 ha [40]. The average
annual loss of fertilizer components from the catchment of coastal rivers—in the case
of mineral nitrogen at 1.00–1.30 kg NNH4+NO3 ·ha
−1 , and in the case of phosphorus at
0.20 kg P 2 O 5 ·ha
−1 . Annually, soil losses in the bottom moraine landscape in Western
Pomerania amounted to 23.9 kg P 2 O 5 ·km
−2 [42]. Durkowski [43] described them
at the level of 4% of the applied fertilizer dose, while every year from intensely
fertilized agricultural areas it amounts to a maximum of 5.5 kg N·ha
−1 and 0.6 kg
P·ha
−1 . According to Lossowa [10], 1–5% of phosphorus and 10–20% of nitrogen
introduced into the soil with mineral fertilizers is washed away into the surrounding
waters. In the Wisła basin from area sources (mainly from agricultural areas), 52%
of nitrogen and 45% of phosphorus come from the Odra catchment—43 and 30%
respectively [44].
The catchments of the studied lakes were intensively used for agriculture. In
the vast majority, these areas belonged to state-owned farms, using very intensive
fertilization of up to 750 kg NPK·ha
−1 [36], exceeding the national average (180–200
kg·ha
−1 ) [40]. In the period from 1979/1980 to 1992/1993. There was a decline in
the country scale, mineral fertilization (on average from 193 to 66 kg NPK·ha
−1 ,
and on individual farms even up to 61 kg·ha
−1 agricultural land) [45]. A similar
tendency was observed in Western Pomerania—in the mid-1970s, fertilization with
mineral fertilizers averaged about 280 kg·ha
−1 , by the end of the eighties it ranged
between 250–280, and in 1992–1993 there was a sharp decrease in fertilization to 63,
1 kg·ha
−1 [46–48]. Since the mid-1970s, the use of lands did not change in this part
of the country—arable lands usually occupied about 400, meadows—from 85 to 90,
pastures—from 37 to 38, and forests—from 265 to 270 thousand. ha. In the 1990s,
the eutrophication of lakes could inhibit a significant reduction in fertilization [15].
It should be noted, however, that large point sources, including municipal sewage,
may outweigh the impact of agriculture on a given basin [2, 3].
Inadequate water and sewage management in rural areas is an important cause
of water eutrophication. At the same time, along with the expansion of water
supply systems, sewage must be taken over and treated. Otherwise, not only rapid
degradation of lakes will occur, but also deterioration of groundwater quality [7, 10].