Mineral substances of grassland in heifer breeding

The paper reports on the results of a six-year (1992-1997) pratotechnic research established on eutrophization of semi-natural grassland (union Cynosurion R.Tx. 1973 association Lolio-Cynosuretum typicum). The experimental site is situated in the region of Strazovske vrchy (north-western part of the Slovak Republic) at an altitude of 600 m above sea level with the mean annual temperature of 7.4 degree C (13.8 degree C for the growing season) and the average precipitation of 805 mm per year (446 mm during the growing season). The three-factor trial comprised three parallel block-type grasslands: - permanent grassland - representing an original semi-natural grassland, - temporary grassland - obtained by radical recovery of permanent grassland (autumn tillage by a plough with low skim, spring and pre-sowing soil treatment, sowing of clover-grass mixture), - reseeded grassland, - established by additional sowing of clover-grass mixture direct into original grassland. All three blocks were offered identical mineral nutrition: - NC - non-fertilized control, - 30P - 30 kg P.ha-1, - 90N - 30 kg P + 90 kg N.ha-1, - 180N - 30 kg P + 180 kg N.ha-1. Phosphorus (in form of superphosphate with 7.9% content of phosphorus) and a part of nitrogen (in form of ammonium nitrate with limestone containing 27.5% of nitrogen) were applied in spring after greening of stands and further two rates followed ten days after the first and second cuts at the latest. All grasslands (a size of randomly arranged plots in four replications was 1.2 x 10 m) were cut three times during vegetation - the first cut being carried out at the beginning of earring, the second cut after 4-5 weeks and the third cut approximately 6-8 weeks after the second cut. The effects of mineral nutrition, cut date and grassland type on mineral substance content in dry matter of grasslands were assessed in terms of standardised daily nutrient requirement in feed ration for two weight categories of heifers (250 and 450 kg, respectively). The results achieved were statistically evaluated by the method of multifactorial analysis of variance and LSD-test (Statgraphics, version 5)