Influence of the soil cover agroecological conditions upon water ecosystems of the Braslav Lakes area | Влияние агроэкологического состояния почвенного покрова на водные экосистемы Браславского Поозерья
2010
Chernysh, A.F. | Kachkov, Yu.P. | Yukhnovets, A.V. | Kartashevich, Z.K. | Davydik, E.E. | Kasyanenko, I.I., Belarus State Univ., Minsk (Belarus)
The paper presents the results of the long-term observations of the erosion process intensity in slope lands (Braslav station) and the chemical composition of water from rivers, streamlets and reclamation canals that discharge into the water reservoirs of the Braslav group of lakes. About 12-13 t/ha of fine earth is washed away annually from slope lands used under tilled crops and from fall-plowed lands, 8.5 – from slope lands under spring crops, 2.1 – under winter crops, and 0.3 t/ha – under perennial grasses. At the same time, the lost of humus from lands under tilled crops and fall-plowed lands is as high as 203.9 kg/ha, total nitrogen – 11.1, mobile phosphorus – 5 and exchange potassium – 4.5 kg/ha. Under spring crops the above values are 88.3; 6.5; 3.1; and 2.4 kg/ha, respectively. The total losses from lands are much lower under winter crops, and, especially, under perennial grasses, where the humus content decreases 45 times, mobile phosphorus – 16, and exchange potassium – 5 times. The most portion of this loss is due to the solid runoff. The more intensive anthropogenic processes result in lowering the relative content of bicarbonates and calcium, and a significant increase of chlorides, sodium and potassium. The maximum concentrations of chlorides, sodium and potassium are in streamlets, where flowing waters from settlements or from extensively tilled watershed areas are accumulated. The phosphorus content of streamlets and canals depends on the watershed land use intensity. All the types of the landscape structure of the streamlet watershed areas are associated with some specific phosphorus concentrations in streamlets and other water flows. The optimum management of watershed areas could decrease the losses of biogenic elements with streamlets and the surface runoff.
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