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

摘要

The aim of this study was to determine the chemical changes in the pasture affected by differentdoses of nitrogen fertilizers and harvest times. It was carried out at Central Anatolian Region duringthe seasons of 2011 and 2012. Experimental plots were formed by 7 m x 12 m. Nitrogen was applied sixdoses (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 and15th of May, 20th of July and 12th of September in the second year). Botanical composition of grasssamples was determined for each plot and then chemically analyzed. Among the grass species Festucaovina, Tymus, Astragalus sp., Artemisia and Agropyron repens were dominant. Increased N rates, from0 to 50 kg N ha-1, caused to increase botanical composition constantly but number of plants wasdecreased. Crude protein content (2.85 g/kd DM), digestible dry matter (13.53 g/kg), digestible proteinratio (0.0015 g/kg DM) and ash content (128.3 g/kg DM) reached to highest levels at 40 kg N ha-1 whilethe highest value of dry matter yield at 50 kg N ha-1. In contrast, Water Soluble Carbohydrate decreasedconstantly. Results of this study revealed that harvest times also had significant effects on chemicalcompositions of permanent grassland