Influence of different systems of grazing, type of swards and fertilizing on underground phytomass of pastures

Abstract

Problems concerning total dry weight and distribution of underground phytomass were studied in a pasture trial at Rapotin near Šumperk, the Czech Republic in the period 1995-1999. The total weight of dry underground pasture phytomass (DUP) was 976 g/m2 (5-year average) in a soil layer of 0-200 mm (both live and dead roots). The DUP was significantly increased by mineral fertilizers (90 kg N/ha, 30 kg P/ha a 90 kg K/ha). The weight of DUP was not significantly influenced by a grazing system, renewal or resowing of the original grassland. In unfertilized plots, DUP weight amounted to 989 g/m2, i.e. 92 g/m2 (8.6%) less than in fertilized plots in the period 1996-1999. In the same period, under the grassland exploited by rotational grazing 1142 and under continuous grazing 1082 g/m2 DUP were determined, i.e. by 60 g/m2 (5.5%) less. The highest DUP weight in the period 1996-1999 was found in autumn 1997 (1222 g/m2) immediately before achieving the maximum forage yield in May 1998. In a layer of 0-20 mm, 54.6% of the total DUP was found. In this surface layer, significant increase in the DUP weight was found in fertilized plots. In 1999, some 88.5 and 90.2% of DUP were concentrated in unfertilized (903 g/m2) and fertilized (952 g/m2) plots, respectively in a layer of 0-100 mm.