Effects of varying nitrogen fertilizer application rates on chemical composition of permanent grassland in Turkey

Abstract

The aim of this study was to determine the chemical changes in the pasture affected by different doses of nitrogen fertilizers and harvest times. It was carried out at Central Anatolian Region during the seasons of 2011 and 2012. Experimental plots were formed by 7 m x 12 m. Nitrogen was applied six doses (annual rate of fertilizer N) as organic nitrogen fertilizer (0, 10, 20, 30, 40, 50 and 60 kg N ha(-1)). Each plot was harvested 3 times (20th of May, 18th of July and 15th of September in the first year and 15th of May, 20th of July and 12th of September in the second year). Botanical composition of grass samples was determined for each plot and then chemically analyzed. Among the grass species Festuca ovina, Tymus, Astragalus sp., Artemisia and Agropyron repens were dominant. Increased N rates, from 0 to 50 kg N ha(-1), caused to increase botanical composition constantly but number of plants was decreased. Crude protein content (2.85 g/kd DM), digestible dry matter (13.53 g/kg), digestible protein ratio (0.0015 g/kg DM) and ash content (128.3 g/kg DM) reached to highest levels at 40 kg N ha(-1) while the highest value of dry matter yield at 50 kg N ha(-1). In contrast, Water Soluble Carbohydrate decreased constantly. Results of this study revealed that harvest times also had significant effects on chemical compositions of permanent grassland