Vliv pastvy ovcí na obsah minerálních látek ve stepních porostech Národní přírodní rezervace Mohelenská hadcová step

Abstract

The aim of the study was to evaluate the effect of sheep pasture on the content of minerals in growth of the Mohelenska Serpentine Steppe National Nature Reserve.Merino sheep pastured on the steppe in 1997–1998, electrical fencer was used. There were 6.8–9.4 sheep per 1 ha in 1997 and 6.7–8.7 sheep per 1 ha in 1998 on the pasture area 4.25 and 6 ha. Samples of steppe growth were taken from five locations with typical fytocenological composition for particular area of steppe. Samples were taken each two weeks during vegetative season from area 3x1 m2. The contents of Ca, P, Na, K, Mg, Mn, Zn, Cu and Fe in dry matter were evaluated. The changes in the content of the nutrients were evaluated depending on the location before, after and during pasture. The values of nutrients were compared with content of these nutrients in meadow and pasture growths (noted in European databases).The content of Ca was from 2.23 to 4.06 g/kg of dry matter. Pasture decreased the variability of location in Ca content and there were significant decreases of Ca content on two locations (P < 0.01). Low content of Ca in steppe growth due to pasture significantly decreased on these locations in comparison with Ca content in pasture growth on no-serpentine soil. The content of P was from 2.23 to 4.06 g/kg of dry matter. Pasture did not affect the variability of location and on one location pasture significantly increased its content (P < 0.01). Despite it the content of P in dry matter was markedly lower than in pasture growths.The content of Na was from 43.88 to 113.97 mg/kg of dry matter. Pasture did not affect the variability of location and its content. The content of Na was markedly lower in steppe growth in comparison with pasture growths. Pasture also did not affect the content of K, which was from 9.96 to 18.10 g/kg of dry matter. But pasture increased the variability of location. The content of K in steppe growth was low in comparison with pasture growths. The content of Mg was from 2.14 to 4.64 g/kg of dry matter. On two locations the content of Mg increased due to pasture (P < 0.05). The content of Mg in steppe growth was comparable with its content in pasture growths. The content of Mn was from 27.55 to 41.32 mg/kg of dry matter and the content of Zn from 12.05 to 26.64 mg/kg of dry matter. Pasture increased the variability of location in both these nutrients. The effect of the pasture on their contents was not (P < 0.05). In steppe growth the content of Mn was markedly lower in comparison with pasture growths and the content of Zn was lower in comparison with pasture growths. The contents of Cu and Fe were from 1.81 to 5.94 mg/kg of dry matter and from 76.1 to 263.2 mg/kg of dry matter. Pasture increased variability of location in the content of Cu and decreased its content in three locations (P < 0.05). The content of Fe was not affected by pasture (P < 0.05). The contents of Cu and Fe were lower in comparison with pasture growths on no-serpentine soils.