Influence of harvest phenophase on the productivity, composition and structure of vegetation cover of a Festuca valesiaca schleich. ex. gaudin grassland from Moldova forest steppe

Abstract

Permanent grasslands are an important source of fodder, due to the areas that they occupy, but also to high and good quality production that can be obtained from them. By using a rational management, grassland production may rise considerably. The objective of this study was to determine the effect of harvesting phenophase under the influence of organic and mineral fertilization on the productivity, composition and structure of vegetation cover of a grassland of Festuca valesiaca Schleich. ex. Gaudin. The researches were conducted at the University of Agricultural Sciences and Veterinary Medicine Iasi, Ezareni farm (47°05'-47°10' north latitude and 27°28'-27°33' eastern longitude). The experimental factors were represented by the harvesting phenophase, with three graduations: a1-harvested at plant height of 15-18 cm, a2-harvested at the ear formation (control) and a3-harvested to full flowering and fertilization with seven graduations: b1- unfertilized (control), b2-N50P50K0 kg·ha-1 annually, b3-N75P75K0 kg·ha-1 annually, b4-N100P100K0 kg·ha-1 annually, b5-10 Mg·ha-1 sheep manure annually, b6-20 Mg·ha-1 annually and b7-30 Mg·ha-1 annually sheep manure applied at two years. The results obtained showed that dry matter production was influenced both by the harvest phenophase and the fertilizer doses used, the higher dry matter production values obtained in the fertilized variants with N100P100K0 kg·ha-1 annually and 30 Mg·ha-1 of two-year-old sheep manure harvested in full-flowering phenophase of the dominant species. Both harvesting in different phenophases, but especially fertilization, led to the modification of structure of vegetation cover by favoring valuable species from fodder point of view.